gstack/test/fixtures/eng-e366-count-public.json

{
  "source": "e366d789342080bb7adf64ed57a82b4e444fba91",
  "windowStart": "2026-09-16T20:22:21.002Z",
  "windowEnd": "2026-09-16T20:43:05.795Z",
  "calls": [
    {
      "sessionId": "21257e30-f7f3-41d2-8147-a93fd5d6d8c6",
      "toolUseId": "toolu_01SZPcg25UVLsDakZUeHSGgS",
      "questions": [
        {
          "question": "D1 — Complexity gate: 5 new classes for a behavior-preserving refactor, or fewer?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md), reorganizing tenant-auth orchestration with no product behavior change.\nELI10: The plan says its goal is to move existing auth code around without changing what users experience, but it introduces five new classes across twelve files. Two of those classes look like they do not earn a class: RequestPolicy is described by the plan itself as stateless with no side effects (that is a function), and TokenStore is never described while AuthCache already wraps the one backing cache. Every extra class is another seam a tired engineer has to trace at 3am when a tenant cannot log in.\nStakes if we pick wrong: too many classes and the refactor ships with duplicated cache-like surfaces (TokenStore vs AuthCache) and a class-shaped wrapper around one pure decision; too few and a genuinely distinct responsibility (if TokenStore has one) gets crammed into AuthCache and re-split later.\nRecommendation: A because the plan's own description of RequestPolicy (PLAN.md:12-13) is the definition of a pure function, and TokenStore has no stated responsibility distinct from AuthCache (PLAN.md:20-21, 45).\nNote: options differ in kind, not coverage — no completeness score.\nThis chooses structure only. Contracts stay fixed (PLAN.md:16-22); the shared mutable AuthCache, the nested try/catch, the regression coverage and the Promise.all change are separate remedies asked later, not decided here.\nPros / cons:\nA) 3 units: AuthBroker, SessionMint, AuthCache; RequestPolicy becomes a pure function; TokenStore folded into AuthCache (recommended)\n  ✅ One cache-facing surface instead of two, so invalidation on logout/revocation/suspension has one place to be right\n  ✅ Access decision is a pure `decideAccess(claims, ctx)` function: trivially unit-testable, no lifecycle, no mocks\n  ❌ If TokenStore turns out to own something the adapter does not (e.g. refresh-token persistence), you rediscover it mid-implementation and re-split\nB) 4 units: AuthBroker, SessionMint, AuthCache, TokenStore; RequestPolicy becomes a pure function\n  ✅ Keeps TokenStore's seam available in case it holds a responsibility the plan did not write down\n  ✅ Still removes the class wrapper around a stateless decision, the clearest over-abstraction in the plan\n  ❌ Two token-holding abstractions remain in one refactor with no written contract distinguishing them; DRY risk is real\nC) Original arrangement: all 5 classes as written (AuthBroker, TokenStore, SessionMint, AuthCache, RequestPolicy)\n  ✅ Matches the author's mental model exactly; no re-planning cost before implementation starts\n  ✅ RequestPolicy as a class leaves room to grow if policy is expected to gain state or dependencies later\n  ❌ Five new seams for a refactor whose stated goal is no behavior change; two of them are unjustified by the plan text\nNet: trading a small chance of re-splitting TokenStore against carrying two undescribed or unnecessary abstractions into a security-sensitive codepath.",
          "header": "Complexity",
          "multiSelect": false,
          "options": [
            {
              "label": "A) 3 units (recommended)",
              "description": "AuthBroker, SessionMint, AuthCache as classes. RequestPolicy becomes a pure exported function decideAccess(claims, ctx) in a policy module. TokenStore folds into AuthCache (one facade over the one backing adapter). Structure only; all other remedies stay pending."
            },
            {
              "label": "B) 4 units",
              "description": "AuthBroker, SessionMint, AuthCache, TokenStore as classes. RequestPolicy becomes a pure exported function. TokenStore kept as its own seam; the plan must then state its responsibility distinct from AuthCache. Structure only; all other remedies stay pending."
            },
            {
              "label": "C) Original 5 classes",
              "description": "Keep AuthBroker, TokenStore, SessionMint, AuthCache, RequestPolicy exactly as the plan lists them across 12 files. Structure only; all other remedies stay pending."
            }
          ]
        }
      ],
      "answered": true,
      "failed": false,
      "answers": {
        "D1 — Complexity gate: 5 new classes for a behavior-preserving refactor, or fewer?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md), reorganizing tenant-auth orchestration with no product behavior change.\nELI10: The plan says its goal is to move existing auth code around without changing what users experience, but it introduces five new classes across twelve files. Two of those classes look like they do not earn a class: RequestPolicy is described by the plan itself as stateless with no side effects (that is a function), and TokenStore is never described while AuthCache already wraps the one backing cache. Every extra class is another seam a tired engineer has to trace at 3am when a tenant cannot log in.\nStakes if we pick wrong: too many classes and the refactor ships with duplicated cache-like surfaces (TokenStore vs AuthCache) and a class-shaped wrapper around one pure decision; too few and a genuinely distinct responsibility (if TokenStore has one) gets crammed into AuthCache and re-split later.\nRecommendation: A because the plan's own description of RequestPolicy (PLAN.md:12-13) is the definition of a pure function, and TokenStore has no stated responsibility distinct from AuthCache (PLAN.md:20-21, 45).\nNote: options differ in kind, not coverage — no completeness score.\nThis chooses structure only. Contracts stay fixed (PLAN.md:16-22); the shared mutable AuthCache, the nested try/catch, the regression coverage and the Promise.all change are separate remedies asked later, not decided here.\nPros / cons:\nA) 3 units: AuthBroker, SessionMint, AuthCache; RequestPolicy becomes a pure function; TokenStore folded into AuthCache (recommended)\n  ✅ One cache-facing surface instead of two, so invalidation on logout/revocation/suspension has one place to be right\n  ✅ Access decision is a pure `decideAccess(claims, ctx)` function: trivially unit-testable, no lifecycle, no mocks\n  ❌ If TokenStore turns out to own something the adapter does not (e.g. refresh-token persistence), you rediscover it mid-implementation and re-split\nB) 4 units: AuthBroker, SessionMint, AuthCache, TokenStore; RequestPolicy becomes a pure function\n  ✅ Keeps TokenStore's seam available in case it holds a responsibility the plan did not write down\n  ✅ Still removes the class wrapper around a stateless decision, the clearest over-abstraction in the plan\n  ❌ Two token-holding abstractions remain in one refactor with no written contract distinguishing them; DRY risk is real\nC) Original arrangement: all 5 classes as written (AuthBroker, TokenStore, SessionMint, AuthCache, RequestPolicy)\n  ✅ Matches the author's mental model exactly; no re-planning cost before implementation starts\n  ✅ RequestPolicy as a class leaves room to grow if policy is expected to gain state or dependencies later\n  ❌ Five new seams for a refactor whose stated goal is no behavior change; two of them are unjustified by the plan text\nNet: trading a small chance of re-splitting TokenStore against carrying two undescribed or unnecessary abstractions into a security-sensitive codepath.": "A) 3 units (recommended)"
      },
      "unansweredQuestionIndices": [],
      "answeredAt": "2026-09-16T20:24:33.441Z"
    },
    {
      "sessionId": "21257e30-f7f3-41d2-8147-a93fd5d6d8c6",
      "toolUseId": "toolu_01PSFmt7Spo3FadR7ALk3kUZ",
      "questions": [
        {
          "question": "D2 — How should AuthBroker and SessionMint get the shared AuthCache: injected, or a module-level global?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md); D1 fixed the structure at 3 units (AuthBroker, SessionMint, AuthCache + decideAccess function).\nELI10: Right now the plan has one cache object living at the top of a module, and both services reach out and grab it. That works until you want to test one service alone, run two tenants' worth of fixtures in one test file, or swap the cache backend: every test shares the same hidden object and leaks state into the next one. Handing the cache in through the constructor makes the dependency visible and gives you one obvious place (the composition root) where the single instance is created.\nStakes if we pick wrong: with the global, a flaky test suite and a cache that cannot be replaced without editing the module; with injection done sloppily, two call sites accidentally construct two AuthCache instances over one adapter and invalidation only hits one.\nRecommendation: A because a security-sensitive cache should have exactly one construction site and every consumer should declare it; this is the explicit-over-clever preference with almost no extra effort (human: ~2h / CC: ~10 min).\nNote: options differ in kind, not coverage — no completeness score.\nThis decides wiring only. The write-after-invalidate guard (R2) is asked next; structure stays at D1's 3 units.\nPros / cons:\nA) Constructor injection from one composition root (recommended)\n  ✅ Each service declares its cache dependency; unit tests construct a fresh AuthCache over a fake adapter per test\n  ✅ Exactly one `new AuthCache(adapter)` call site, so the \"one backing cache\" contract (PLAN.md:21) is enforced by construction\n  ❌ Every place that instantiates AuthBroker or SessionMint must pass the cache; a handful of call sites change\nB) Module-level export as planned\n  ✅ Zero wiring changes; matches the plan text exactly and is the fastest path to a green build\n  ✅ Guarantees a single instance by module semantics without a composition root\n  ❌ Hidden coupling and cross-test state leakage; replacing the adapter means editing the module, not the wiring\nC) Module-level export plus an explicit `resetForTests()` hook\n  ✅ Keeps the plan's import-and-use ergonomics while giving tests a way to clear shared state\n  ✅ Smallest change that addresses the test-isolation symptom\n  ❌ Test-only hooks in production auth code are a smell; the dependency is still invisible at the call site\nNet: trading a few constructor-signature edits against a hidden global in the codepath that decides who gets into which tenant.",
          "header": "Cache wiring",
          "multiSelect": false,
          "options": [
            {
              "label": "A) Constructor injection (recommended)",
              "description": "One composition root creates a single `AuthCache(adapter)` and passes it to `new AuthBroker(cache, ...)` and `new SessionMint(cache, ...)`. No module-level export of the instance. Tests construct their own AuthCache over a fake adapter. Wiring only; R2 guard stays pending."
            },
            {
              "label": "B) Module-level export",
              "description": "Keep the plan as written: `AuthCache` instance exported from its module and imported by both services. Wiring only; R2 guard stays pending."
            },
            {
              "label": "C) Module global + resetForTests()",
              "description": "Keep the module-level export and add an explicit `resetForTests()` that swaps or clears the shared instance for test isolation. Wiring only; R2 guard stays pending."
            }
          ]
        }
      ],
      "answered": true,
      "failed": false,
      "answers": {
        "D2 — How should AuthBroker and SessionMint get the shared AuthCache: injected, or a module-level global?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md); D1 fixed the structure at 3 units (AuthBroker, SessionMint, AuthCache + decideAccess function).\nELI10: Right now the plan has one cache object living at the top of a module, and both services reach out and grab it. That works until you want to test one service alone, run two tenants' worth of fixtures in one test file, or swap the cache backend: every test shares the same hidden object and leaks state into the next one. Handing the cache in through the constructor makes the dependency visible and gives you one obvious place (the composition root) where the single instance is created.\nStakes if we pick wrong: with the global, a flaky test suite and a cache that cannot be replaced without editing the module; with injection done sloppily, two call sites accidentally construct two AuthCache instances over one adapter and invalidation only hits one.\nRecommendation: A because a security-sensitive cache should have exactly one construction site and every consumer should declare it; this is the explicit-over-clever preference with almost no extra effort (human: ~2h / CC: ~10 min).\nNote: options differ in kind, not coverage — no completeness score.\nThis decides wiring only. The write-after-invalidate guard (R2) is asked next; structure stays at D1's 3 units.\nPros / cons:\nA) Constructor injection from one composition root (recommended)\n  ✅ Each service declares its cache dependency; unit tests construct a fresh AuthCache over a fake adapter per test\n  ✅ Exactly one `new AuthCache(adapter)` call site, so the \"one backing cache\" contract (PLAN.md:21) is enforced by construction\n  ❌ Every place that instantiates AuthBroker or SessionMint must pass the cache; a handful of call sites change\nB) Module-level export as planned\n  ✅ Zero wiring changes; matches the plan text exactly and is the fastest path to a green build\n  ✅ Guarantees a single instance by module semantics without a composition root\n  ❌ Hidden coupling and cross-test state leakage; replacing the adapter means editing the module, not the wiring\nC) Module-level export plus an explicit `resetForTests()` hook\n  ✅ Keeps the plan's import-and-use ergonomics while giving tests a way to clear shared state\n  ✅ Smallest change that addresses the test-isolation symptom\n  ❌ Test-only hooks in production auth code are a smell; the dependency is still invisible at the call site\nNet: trading a few constructor-signature edits against a hidden global in the codepath that decides who gets into which tenant.": "A) Constructor injection (recommended)"
      },
      "unansweredQuestionIndices": [],
      "answeredAt": "2026-09-16T20:27:01.392Z"
    },
    {
      "sessionId": "21257e30-f7f3-41d2-8147-a93fd5d6d8c6",
      "toolUseId": "toolu_01WeCkHwV5qHgHvVYnhggqQd",
      "questions": [
        {
          "question": "D3 — Should AuthCache refuse a cache write that started before an invalidation for the same tenant?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md); D1 fixed 3 units, D2 fixed constructor injection of one AuthCache.\nELI10: Two services write into the same cache and the plan says nothing serializes those writes. Picture tenant T getting suspended: the invalidation hook wipes T's entries, but SessionMint was already halfway through minting a session for T and writes a fresh entry a few milliseconds later. That entry survives until it expires, so a suspended tenant keeps getting in. The fix is a small stamp: each tenant has an invalidation counter, a write remembers the counter it saw when it started, and the cache drops the write if the counter moved.\nStakes if we pick wrong: without the guard, logout, revocation and suspension can be silently undone by a racing write and nobody sees an error; with the guard done wrong, legitimate writes get dropped and users see extra IDP round trips (a cache miss, not a lockout).\nRecommendation: A because the failure is silent, security-relevant, and the guard is a few lines inside the one facade that D1 and D2 just made the single write path (human: ~1 day incl. tests / CC: ~20 min).\nCompleteness: A=10/10, B=3/10, C=n/a (investigation only, no remedy)\nPros / cons:\nA) Per-tenant invalidation generation with compare-and-set writes in AuthCache (recommended)\n  ✅ Suspension, revocation and logout cannot be resurrected by a racing mint or validation write; the invariant lives in one place\n  ✅ Failure mode degrades to a cache miss (one extra IDP call), never to a wrongly cached allow\n  ❌ Adds state to the facade (a generation map) and a deterministic concurrency test that must be written carefully\nB) No guard; both services write directly as planned\n  ✅ Smallest diff; keeps the facade a thin pass-through over the adapter exactly as PLAN.md:20-21 describes\n  ✅ If the legacy flow already had this race, this option does not make anything worse than today\n  ❌ A suspended or logged-out tenant can retain cached access until expiry with no log line; silent security regression risk\nC) Investigate first: bounded probe of the existing adapter's ordering guarantees, then decide\n  ✅ Avoids building a guard the adapter may already provide (e.g. versioned keys or invalidate-then-fence semantics)\n  ✅ Cheap: read the adapter and its invalidation tests, report what ordering exists (CC: ~5 min once source is available)\n  ❌ Leaves the race unresolved in the plan until the probe runs; implementation must not start this seam before the follow-up answer\nNet: trading a small generation map and one concurrency test against a silent way for revoked access to come back.",
          "header": "Cache race",
          "multiSelect": false,
          "options": [
            {
              "label": "A) Generation guard (recommended)",
              "description": "AuthCache keeps a per-tenant invalidation generation; every invalidation hook (logout, revocation, suspension) bumps it; `put()` carries the generation observed at read time and is dropped if the tenant's generation has advanced. Includes the deterministic concurrency test. Applies inside the facade only."
            },
            {
              "label": "B) No guard",
              "description": "Both services write to AuthCache directly with no ordering check, as the plan describes. Race is recorded as an accepted risk in the report."
            },
            {
              "label": "C) Investigate first",
              "description": "Bounded probe of the existing adapter and its invalidation tests for ordering guarantees before choosing. Approves no implementation; the guard choice stays pending for a follow-up answer."
            }
          ]
        }
      ],
      "answered": true,
      "failed": false,
      "answers": {
        "D3 — Should AuthCache refuse a cache write that started before an invalidation for the same tenant?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md); D1 fixed 3 units, D2 fixed constructor injection of one AuthCache.\nELI10: Two services write into the same cache and the plan says nothing serializes those writes. Picture tenant T getting suspended: the invalidation hook wipes T's entries, but SessionMint was already halfway through minting a session for T and writes a fresh entry a few milliseconds later. That entry survives until it expires, so a suspended tenant keeps getting in. The fix is a small stamp: each tenant has an invalidation counter, a write remembers the counter it saw when it started, and the cache drops the write if the counter moved.\nStakes if we pick wrong: without the guard, logout, revocation and suspension can be silently undone by a racing write and nobody sees an error; with the guard done wrong, legitimate writes get dropped and users see extra IDP round trips (a cache miss, not a lockout).\nRecommendation: A because the failure is silent, security-relevant, and the guard is a few lines inside the one facade that D1 and D2 just made the single write path (human: ~1 day incl. tests / CC: ~20 min).\nCompleteness: A=10/10, B=3/10, C=n/a (investigation only, no remedy)\nPros / cons:\nA) Per-tenant invalidation generation with compare-and-set writes in AuthCache (recommended)\n  ✅ Suspension, revocation and logout cannot be resurrected by a racing mint or validation write; the invariant lives in one place\n  ✅ Failure mode degrades to a cache miss (one extra IDP call), never to a wrongly cached allow\n  ❌ Adds state to the facade (a generation map) and a deterministic concurrency test that must be written carefully\nB) No guard; both services write directly as planned\n  ✅ Smallest diff; keeps the facade a thin pass-through over the adapter exactly as PLAN.md:20-21 describes\n  ✅ If the legacy flow already had this race, this option does not make anything worse than today\n  ❌ A suspended or logged-out tenant can retain cached access until expiry with no log line; silent security regression risk\nC) Investigate first: bounded probe of the existing adapter's ordering guarantees, then decide\n  ✅ Avoids building a guard the adapter may already provide (e.g. versioned keys or invalidate-then-fence semantics)\n  ✅ Cheap: read the adapter and its invalidation tests, report what ordering exists (CC: ~5 min once source is available)\n  ❌ Leaves the race unresolved in the plan until the probe runs; implementation must not start this seam before the follow-up answer\nNet: trading a small generation map and one concurrency test against a silent way for revoked access to come back.": "A) Generation guard (recommended)"
      },
      "unansweredQuestionIndices": [],
      "answeredAt": "2026-09-16T20:27:55.565Z"
    },
    {
      "sessionId": "21257e30-f7f3-41d2-8147-a93fd5d6d8c6",
      "toolUseId": "toolu_01AovjSFp1uCLC3QgiZt7HKs",
      "questions": [
        {
          "question": "D4 — How should validateAndDispatch() handle errors: one explicit error map, or keep the nested try/catch?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md); structure, wiring and the cache guard are fixed (D1–D3).\nELI10: The function that decides whether a request gets in has three try/catch blocks nested inside each other, and each one quietly eats a different kind of error. When an error is eaten, the code after it keeps running as if nothing went wrong, so a failed token check can fall through to dispatch, or fail with no log line to explain a locked-out user. The fix is to make the flow a straight line (validate, decide, dispatch) and have one place that says, for each error type, exactly what the caller gets back and what gets logged.\nStakes if we pick wrong: a swallowed validation error can become an allow (security), and a swallowed IDP outage becomes a silent lockout with no log to debug at 3am.\nRecommendation: A because deny-by-default with an explicit error map is the smallest change that makes every failure path both safe and visible; it also drops the function well under 60 lines (human: ~4h / CC: ~15 min).\nCompleteness: A=10/10, B=6/10, C=2/10\nPros / cons:\nA) Linear flow with one explicit error map, deny-by-default, structured logs (recommended)\n  ✅ Every error class has a named outcome (e.g. ValidationError → deny 401, PolicyDenied → deny 403, IdpUnavailable → 503 + retryable) and a log line with tenant and request IDs\n  ✅ Unknown errors deny and re-throw, so nothing new can slip through to dispatch; table-driven tests cover each row\n  ❌ Callers that relied on a swallowed error producing a soft result may see a new explicit deny; the regression suite must catch this\nB) Keep the nested blocks; each catch logs and returns an explicit deny\n  ✅ Minimal structural change to a function the team already knows\n  ✅ Stops the silent-swallow behavior, which is the most dangerous part\n  ❌ Still 60 lines and three nesting levels; the outcome for each error class is spread across the function instead of one table\nC) Keep as described: nested blocks that swallow\n  ✅ Zero risk of changing any caller-visible behavior in this refactor\n  ✅ No new tests required for this function beyond what the plan already lists\n  ❌ Errors keep disappearing in the codepath that grants access; incompatible with the \"explicit over clever\" preference\nNet: trading a small chance that a caller depended on a swallowed error against silent failures in the access-granting path.",
          "header": "Error handling",
          "multiSelect": false,
          "options": [
            {
              "label": "A) Explicit error map (recommended)",
              "description": "Rewrite validateAndDispatch() as validate → decideAccess → dispatch inside one try; a single catch maps each known error class to an explicit outcome and structured log; unknown errors deny and re-throw. Table-driven unit test per error class."
            },
            {
              "label": "B) Log-and-deny in each catch",
              "description": "Keep the three nested try/catch blocks; replace each swallow with a log line and an explicit deny result. No restructuring."
            },
            {
              "label": "C) Keep as described",
              "description": "Leave validateAndDispatch() as the plan describes it; swallowing behavior recorded as an accepted risk."
            }
          ]
        }
      ],
      "answered": true,
      "failed": false,
      "answers": {
        "D4 — How should validateAndDispatch() handle errors: one explicit error map, or keep the nested try/catch?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md); structure, wiring and the cache guard are fixed (D1–D3).\nELI10: The function that decides whether a request gets in has three try/catch blocks nested inside each other, and each one quietly eats a different kind of error. When an error is eaten, the code after it keeps running as if nothing went wrong, so a failed token check can fall through to dispatch, or fail with no log line to explain a locked-out user. The fix is to make the flow a straight line (validate, decide, dispatch) and have one place that says, for each error type, exactly what the caller gets back and what gets logged.\nStakes if we pick wrong: a swallowed validation error can become an allow (security), and a swallowed IDP outage becomes a silent lockout with no log to debug at 3am.\nRecommendation: A because deny-by-default with an explicit error map is the smallest change that makes every failure path both safe and visible; it also drops the function well under 60 lines (human: ~4h / CC: ~15 min).\nCompleteness: A=10/10, B=6/10, C=2/10\nPros / cons:\nA) Linear flow with one explicit error map, deny-by-default, structured logs (recommended)\n  ✅ Every error class has a named outcome (e.g. ValidationError → deny 401, PolicyDenied → deny 403, IdpUnavailable → 503 + retryable) and a log line with tenant and request IDs\n  ✅ Unknown errors deny and re-throw, so nothing new can slip through to dispatch; table-driven tests cover each row\n  ❌ Callers that relied on a swallowed error producing a soft result may see a new explicit deny; the regression suite must catch this\nB) Keep the nested blocks; each catch logs and returns an explicit deny\n  ✅ Minimal structural change to a function the team already knows\n  ✅ Stops the silent-swallow behavior, which is the most dangerous part\n  ❌ Still 60 lines and three nesting levels; the outcome for each error class is spread across the function instead of one table\nC) Keep as described: nested blocks that swallow\n  ✅ Zero risk of changing any caller-visible behavior in this refactor\n  ✅ No new tests required for this function beyond what the plan already lists\n  ❌ Errors keep disappearing in the codepath that grants access; incompatible with the \"explicit over clever\" preference\nNet: trading a small chance that a caller depended on a swallowed error against silent failures in the access-granting path.": "A) Explicit error map (recommended)"
      },
      "unansweredQuestionIndices": [],
      "answeredAt": "2026-09-16T20:29:03.822Z"
    },
    {
      "sessionId": "21257e30-f7f3-41d2-8147-a93fd5d6d8c6",
      "toolUseId": "toolu_016KEtKeHmcivSW9sEF96YxQ",
      "questions": [
        {
          "question": "D5 — Should the read → miss → load → write sequence live once in AuthCache.getOrLoad(), or in each service?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md); D1–D4 fixed structure, injection, the generation guard and the error map.\nELI10: Both AuthBroker and SessionMint need the same dance: look in the cache, if it is not there ask the IDP, then store the answer. If each service writes that dance itself, the generation guard from D3 has to be remembered in two places and a future fix lands in one and not the other. Putting the dance in one method on the cache facade means the guard is applied automatically wherever a load happens.\nStakes if we pick wrong: with duplication, one service eventually bypasses the guard or diverges on key construction and a tenant-key bug appears in only one flow; with a bad abstraction, a loader signature too generic for the two real callers.\nRecommendation: A because the two callers are known now, the guard from D3 must wrap every write, and one helper is the DRY-aggressive default for this codebase (human: ~3h / CC: ~10 min).\nCompleteness: A=10/10, B=5/10, C=n/a (deferral, no remedy)\nPros / cons:\nA) One `AuthCache.getOrLoad(key, loader)` used by both services (recommended)\n  ✅ The D3 generation guard and the tenant/issuer/audience/policy-version key construction are applied in exactly one place\n  ✅ Both services shrink to \"call getOrLoad with my loader\"; tests for the miss path are written once\n  ❌ A loader callback is one more indirection to read; if the two callers turn out to need different miss semantics the helper grows a flag\nB) Each service keeps its own read/miss/write sequence\n  ✅ Each flow stays fully explicit at its own call site with no callback indirection\n  ✅ No shared helper to design before the two callers exist\n  ❌ Two copies of the miss path; the guard and key rules must be maintained twice and tested twice\nC) Defer until duplication is confirmed in code\n  ✅ Avoids abstracting on an inference; the plan text does not literally show both sequences\n  ✅ Cheap to revisit once the first service is written\n  ❌ Leaves the guard-application rule unowned during implementation; the second service may ship before the revisit\nNet: trading a small callback indirection against maintaining the security-relevant miss path in two places.",
          "header": "DRY miss path",
          "multiSelect": false,
          "options": [
            {
              "label": "A) getOrLoad in AuthCache (recommended)",
              "description": "Add `AuthCache.getOrLoad(key, loader)`: read; on miss call loader; write through the R2 generation guard. AuthBroker and SessionMint both use it for their cache-miss sequences. Tested once in AuthCache."
            },
            {
              "label": "B) Per-service sequences",
              "description": "Each service implements its own read → miss → IDP → write against AuthCache.get/put. Guard and key rules maintained at both sites."
            },
            {
              "label": "C) Defer",
              "description": "Implement per-service first; revisit consolidation when the duplication is confirmed in code. Approves no consolidation now."
            }
          ]
        }
      ],
      "answered": true,
      "failed": false,
      "answers": {
        "D5 — Should the read → miss → load → write sequence live once in AuthCache.getOrLoad(), or in each service?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md); D1–D4 fixed structure, injection, the generation guard and the error map.\nELI10: Both AuthBroker and SessionMint need the same dance: look in the cache, if it is not there ask the IDP, then store the answer. If each service writes that dance itself, the generation guard from D3 has to be remembered in two places and a future fix lands in one and not the other. Putting the dance in one method on the cache facade means the guard is applied automatically wherever a load happens.\nStakes if we pick wrong: with duplication, one service eventually bypasses the guard or diverges on key construction and a tenant-key bug appears in only one flow; with a bad abstraction, a loader signature too generic for the two real callers.\nRecommendation: A because the two callers are known now, the guard from D3 must wrap every write, and one helper is the DRY-aggressive default for this codebase (human: ~3h / CC: ~10 min).\nCompleteness: A=10/10, B=5/10, C=n/a (deferral, no remedy)\nPros / cons:\nA) One `AuthCache.getOrLoad(key, loader)` used by both services (recommended)\n  ✅ The D3 generation guard and the tenant/issuer/audience/policy-version key construction are applied in exactly one place\n  ✅ Both services shrink to \"call getOrLoad with my loader\"; tests for the miss path are written once\n  ❌ A loader callback is one more indirection to read; if the two callers turn out to need different miss semantics the helper grows a flag\nB) Each service keeps its own read/miss/write sequence\n  ✅ Each flow stays fully explicit at its own call site with no callback indirection\n  ✅ No shared helper to design before the two callers exist\n  ❌ Two copies of the miss path; the guard and key rules must be maintained twice and tested twice\nC) Defer until duplication is confirmed in code\n  ✅ Avoids abstracting on an inference; the plan text does not literally show both sequences\n  ✅ Cheap to revisit once the first service is written\n  ❌ Leaves the guard-application rule unowned during implementation; the second service may ship before the revisit\nNet: trading a small callback indirection against maintaining the security-relevant miss path in two places.": "A) getOrLoad in AuthCache (recommended)"
      },
      "unansweredQuestionIndices": [],
      "answeredAt": "2026-09-16T20:29:50.004Z"
    },
    {
      "sessionId": "21257e30-f7f3-41d2-8147-a93fd5d6d8c6",
      "toolUseId": "toolu_013hpuevybPNEYK628sKWgGy",
      "questions": [
        {
          "question": "D6 — How do we prove the rewritten auth flow behaves exactly like legacyAuthFlow() before the old one is deleted?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md); D1–D5 fixed structure, injection, guard, error map and getOrLoad.\nELI10: The plan rewrites the function every tenant login goes through and, as written, has no test that says \"the new one answers the same as the old one.\" The way to get that safely is to write the tests against the OLD function first, so they capture what it actually does today (including its quirks), then point the same tests at the new function. For an auth path you can go one step further and run both in production for a while, letting the old one decide while logging any disagreement.\nStakes if we pick wrong: a tenant that could log in yesterday cannot today, or a token that should be rejected is accepted, and there is no test that would have caught it before deploy.\nRecommendation: B because characterization tests catch what you thought of and the shadow compare catches what you did not; on an auth path the extra flag is cheap insurance and is removed when the window closes (A: human ~1.5 days / CC ~30 min; B: human ~3 days / CC ~45 min).\nCompleteness: A=9/10, B=10/10, C=5/10\nPros / cons:\nA) Characterization suite captured from legacyAuthFlow() first, then run against the new flow\n  ✅ Locks in every listed outcome class before a line of the rewrite exists; failures point at the exact diverging case\n  ✅ Also serves as the acceptance suite for D4: every intentionally changed outcome is listed and asserted as changed, nothing changes silently\n  ❌ Only covers cases someone thought to write; real token shapes and IDP behaviors in production may differ\nB) A plus a flag-gated shadow compare in production for a bounded window (recommended)\n  ✅ Real traffic across real tenants checks the rewrite against the legacy decision; mismatches are logged with tenant and case, never enforced\n  ✅ Reversible by construction: legacy stays authoritative until the flag flips, so rollback is a config change\n  ❌ Adds a flag, a compare hook and a cleanup task; doubles IDP calls during the window unless the compare reuses the cached result\nC) Happy-path characterization only (valid and expired token)\n  ✅ Fast to write and covers the two most common outcomes users hit every day\n  ✅ Still better than the plan's zero regression coverage\n  ❌ Revocation, suspension, cross-tenant and IDP-failure paths, the ones with security consequences, remain unproven\nNet: trading a temporary flag and compare hook against discovering an auth regression from a tenant's support ticket.",
          "header": "Regression",
          "multiSelect": false,
          "options": [
            {
              "label": "A) Characterization suite",
              "description": "Write the regression suite against legacyAuthFlow() before the rewrite covering valid, expired, revoked, logged-out, suspended tenant, cross-tenant, policy-version bump, malformed token, IDP unavailable and IDP timeout; assert outcome class and cache state. The new flow must pass it; intentional D4 differences are listed and asserted explicitly."
            },
            {
              "label": "B) Characterization + shadow compare (recommended)",
              "description": "Everything in A, plus a flag-gated shadow mode where the new flow runs alongside legacy in production for a bounded window; legacy decides, mismatches are logged and alerted; the flag flips only after a clean window; flag and legacy are removed afterwards."
            },
            {
              "label": "C) Happy path only",
              "description": "Characterization tests for valid and expired token only. The remaining legacy outcomes are recorded as unproven in the report."
            }
          ]
        }
      ],
      "answered": true,
      "failed": false,
      "answers": {
        "D6 — How do we prove the rewritten auth flow behaves exactly like legacyAuthFlow() before the old one is deleted?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md); D1–D5 fixed structure, injection, guard, error map and getOrLoad.\nELI10: The plan rewrites the function every tenant login goes through and, as written, has no test that says \"the new one answers the same as the old one.\" The way to get that safely is to write the tests against the OLD function first, so they capture what it actually does today (including its quirks), then point the same tests at the new function. For an auth path you can go one step further and run both in production for a while, letting the old one decide while logging any disagreement.\nStakes if we pick wrong: a tenant that could log in yesterday cannot today, or a token that should be rejected is accepted, and there is no test that would have caught it before deploy.\nRecommendation: B because characterization tests catch what you thought of and the shadow compare catches what you did not; on an auth path the extra flag is cheap insurance and is removed when the window closes (A: human ~1.5 days / CC ~30 min; B: human ~3 days / CC ~45 min).\nCompleteness: A=9/10, B=10/10, C=5/10\nPros / cons:\nA) Characterization suite captured from legacyAuthFlow() first, then run against the new flow\n  ✅ Locks in every listed outcome class before a line of the rewrite exists; failures point at the exact diverging case\n  ✅ Also serves as the acceptance suite for D4: every intentionally changed outcome is listed and asserted as changed, nothing changes silently\n  ❌ Only covers cases someone thought to write; real token shapes and IDP behaviors in production may differ\nB) A plus a flag-gated shadow compare in production for a bounded window (recommended)\n  ✅ Real traffic across real tenants checks the rewrite against the legacy decision; mismatches are logged with tenant and case, never enforced\n  ✅ Reversible by construction: legacy stays authoritative until the flag flips, so rollback is a config change\n  ❌ Adds a flag, a compare hook and a cleanup task; doubles IDP calls during the window unless the compare reuses the cached result\nC) Happy-path characterization only (valid and expired token)\n  ✅ Fast to write and covers the two most common outcomes users hit every day\n  ✅ Still better than the plan's zero regression coverage\n  ❌ Revocation, suspension, cross-tenant and IDP-failure paths, the ones with security consequences, remain unproven\nNet: trading a temporary flag and compare hook against discovering an auth regression from a tenant's support ticket.": "A) Characterization suite"
      },
      "unansweredQuestionIndices": [],
      "answeredAt": "2026-09-16T20:30:50.274Z"
    },
    {
      "sessionId": "21257e30-f7f3-41d2-8147-a93fd5d6d8c6",
      "toolUseId": "toolu_017CV6EsYRVnke7BcnTLDEzh",
      "questions": [
        {
          "question": "D7 — How deep should the integration test for the new flow go: a two-tenant end-to-end scenario, or component-level only?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md); D1–D6 fixed structure, wiring, guard, error map, getOrLoad and the regression suite.\nELI10: Unit tests prove each piece works alone; the bugs in auth systems usually live in the seams, like tenant A's suspension accidentally clearing tenant B's sessions, or the cache key missing one field so two tenants share an entry. One end-to-end test that runs two tenants through the whole login-to-dispatch path with a fake identity provider catches exactly those seam bugs. It is the kind of test you want to fail in CI, not in a customer's browser.\nStakes if we pick wrong: a cross-tenant leak or a suspension that does not stick reaches production because every unit test passed in isolation.\nRecommendation: A because auth flows spanning 3+ components are the textbook E2E case and the fake IDP makes it deterministic (human: ~1 day / CC: ~20 min).\nCompleteness: A=10/10, B=7/10\nPros / cons:\nA) Two-tenant E2E against a fake IDP, including suspension mid-session, cross-tenant token, IDP outage and policy-version bump (recommended)\n  ✅ Exercises AuthBroker, decideAccess, AuthCache (with the D3 guard), SessionMint and dispatch together across two tenants\n  ✅ Failure modes that matter to real users (suspension not sticking, cross-tenant leak, IDP down) are asserted end to end\n  ❌ Needs a fake IDP fixture and takes longer per run than unit tests; must stay deterministic (no real network)\nB) Component-level integration only\n  ✅ Each unit is verified against fake collaborators quickly; no fixture for a full IDP conversation\n  ✅ Matches the plan's wording of \"unit and integration coverage\" with minimal extra scope\n  ❌ Seam bugs between units (key construction, invalidation propagation, dispatch after deny) are not exercised together\nNet: trading one fake-IDP fixture against finding tenant-isolation bugs only in production.",
          "header": "E2E depth",
          "multiSelect": false,
          "options": [
            {
              "label": "A) Two-tenant E2E (recommended)",
              "description": "One end-to-end test file against a fake IDP: tenants A and B log in, validate, decideAccess and dispatch; cross-tenant token rejected; suspending A mid-session denies A's next request and leaves B untouched; IDP outage yields the explicit 503 path; policy-version bump forces a re-validate. Plus the common-work facade contract tests."
            },
            {
              "label": "B) Component-level only",
              "description": "Integration tests per unit against fake adapter and fake IDP; no cross-unit scenario. Plus the common-work facade contract tests."
            }
          ]
        }
      ],
      "answered": true,
      "failed": false,
      "answers": {
        "D7 — How deep should the integration test for the new flow go: a two-tenant end-to-end scenario, or component-level only?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md); D1–D6 fixed structure, wiring, guard, error map, getOrLoad and the regression suite.\nELI10: Unit tests prove each piece works alone; the bugs in auth systems usually live in the seams, like tenant A's suspension accidentally clearing tenant B's sessions, or the cache key missing one field so two tenants share an entry. One end-to-end test that runs two tenants through the whole login-to-dispatch path with a fake identity provider catches exactly those seam bugs. It is the kind of test you want to fail in CI, not in a customer's browser.\nStakes if we pick wrong: a cross-tenant leak or a suspension that does not stick reaches production because every unit test passed in isolation.\nRecommendation: A because auth flows spanning 3+ components are the textbook E2E case and the fake IDP makes it deterministic (human: ~1 day / CC: ~20 min).\nCompleteness: A=10/10, B=7/10\nPros / cons:\nA) Two-tenant E2E against a fake IDP, including suspension mid-session, cross-tenant token, IDP outage and policy-version bump (recommended)\n  ✅ Exercises AuthBroker, decideAccess, AuthCache (with the D3 guard), SessionMint and dispatch together across two tenants\n  ✅ Failure modes that matter to real users (suspension not sticking, cross-tenant leak, IDP down) are asserted end to end\n  ❌ Needs a fake IDP fixture and takes longer per run than unit tests; must stay deterministic (no real network)\nB) Component-level integration only\n  ✅ Each unit is verified against fake collaborators quickly; no fixture for a full IDP conversation\n  ✅ Matches the plan's wording of \"unit and integration coverage\" with minimal extra scope\n  ❌ Seam bugs between units (key construction, invalidation propagation, dispatch after deny) are not exercised together\nNet: trading one fake-IDP fixture against finding tenant-isolation bugs only in production.": "A) Two-tenant E2E (recommended)"
      },
      "unansweredQuestionIndices": [],
      "answeredAt": "2026-09-16T20:31:42.536Z"
    },
    {
      "sessionId": "21257e30-f7f3-41d2-8147-a93fd5d6d8c6",
      "toolUseId": "toolu_019hohyrdFS7B3vyLUVWjGj7",
      "questions": [
        {
          "question": "D8 — When should the 5 IDP calls be parallelized: as a separate final commit after regression is green, deferred, or inline in the refactor?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md); D1–D7 fixed structure, wiring, guard, error map, getOrLoad, regression suite and E2E depth.\nELI10: Making five calls at once instead of one after another is a real speed win for every login, but it is also a behavior change: errors arrive in a different order, five requests hit the identity provider at the same instant, and if one call secretly needs another's answer it breaks. The plan's goal is \"no behavior change,\" so the clean move is to finish the reorganization, prove it matches the old flow with the regression suite, then flip to parallel in its own commit where any difference is obviously caused by that one change.\nStakes if we pick wrong: mixed into the refactor, a regression-suite failure could be either the restructure or the parallelization and you cannot tell which; deferred forever, users keep paying five round trips on every validation.\nRecommendation: A because it keeps structural and behavioral changes in separate commits (Beck) while still landing the win on this branch; the probe of independence and IDP limits is a few minutes once source is available (human: ~half day / CC: ~15 min).\nNote: options differ in kind, not coverage — no completeness score.\nPros / cons:\nA) Separate final commit after the regression suite is green, gated on the independence and rate-limit probe (recommended)\n  ✅ A regression failure after this commit has exactly one cause; rollback is one revert with the refactor intact\n  ✅ The \"calls are independent\" claim is checked against source, and IDP concurrency limits are confirmed before five simultaneous requests ship\n  ❌ One extra commit and a short probe before the latency win lands\nB) Keep sequential in this refactor; defer parallelization to a TODO\n  ✅ The branch stays a pure reorganization with zero timing or error-ordering change\n  ✅ No IDP rate-limit risk introduced by this work\n  ❌ A known 5x-round-trip latency cost on every validation stays in production with no scheduled fix\nC) Promise.all inline in the refactor commit as the plan proposes\n  ✅ Fewest commits; the win ships with the refactor\n  ✅ No separate PR or coordination step\n  ❌ Mixes a behavior change into a \"no behavior change\" refactor; regression-suite failures become ambiguous and the independence claim ships unverified\nNet: trading one extra commit and a short probe against ambiguous regression failures in the auth path.",
          "header": "IDP parallel",
          "multiSelect": false,
          "options": [
            {
              "label": "A) Separate final commit (recommended)",
              "description": "Land Promise.all as its own last commit on this branch after the D6 characterization suite is green against the new flow. Preconditions: bounded probe confirms no call consumes another's output and the IDP tolerates 5 concurrent calls per validation; fail-fast semantics, first rejection routed through the D4 error map; before/after latency recorded in the PR."
            },
            {
              "label": "B) Defer to TODO",
              "description": "Keep the 5 calls sequential in this refactor. Parallelization becomes a TODO with the same preconditions. No timing change on this branch."
            },
            {
              "label": "C) Inline in refactor",
              "description": "Apply Promise.all inside the refactor commit as the plan proposes; no independence probe required beforehand."
            }
          ]
        }
      ],
      "answered": true,
      "failed": false,
      "answers": {
        "D8 — When should the 5 IDP calls be parallelized: as a separate final commit after regression is green, deferred, or inline in the refactor?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md); D1–D7 fixed structure, wiring, guard, error map, getOrLoad, regression suite and E2E depth.\nELI10: Making five calls at once instead of one after another is a real speed win for every login, but it is also a behavior change: errors arrive in a different order, five requests hit the identity provider at the same instant, and if one call secretly needs another's answer it breaks. The plan's goal is \"no behavior change,\" so the clean move is to finish the reorganization, prove it matches the old flow with the regression suite, then flip to parallel in its own commit where any difference is obviously caused by that one change.\nStakes if we pick wrong: mixed into the refactor, a regression-suite failure could be either the restructure or the parallelization and you cannot tell which; deferred forever, users keep paying five round trips on every validation.\nRecommendation: A because it keeps structural and behavioral changes in separate commits (Beck) while still landing the win on this branch; the probe of independence and IDP limits is a few minutes once source is available (human: ~half day / CC: ~15 min).\nNote: options differ in kind, not coverage — no completeness score.\nPros / cons:\nA) Separate final commit after the regression suite is green, gated on the independence and rate-limit probe (recommended)\n  ✅ A regression failure after this commit has exactly one cause; rollback is one revert with the refactor intact\n  ✅ The \"calls are independent\" claim is checked against source, and IDP concurrency limits are confirmed before five simultaneous requests ship\n  ❌ One extra commit and a short probe before the latency win lands\nB) Keep sequential in this refactor; defer parallelization to a TODO\n  ✅ The branch stays a pure reorganization with zero timing or error-ordering change\n  ✅ No IDP rate-limit risk introduced by this work\n  ❌ A known 5x-round-trip latency cost on every validation stays in production with no scheduled fix\nC) Promise.all inline in the refactor commit as the plan proposes\n  ✅ Fewest commits; the win ships with the refactor\n  ✅ No separate PR or coordination step\n  ❌ Mixes a behavior change into a \"no behavior change\" refactor; regression-suite failures become ambiguous and the independence claim ships unverified\nNet: trading one extra commit and a short probe against ambiguous regression failures in the auth path.": "A) Separate final commit (recommended)"
      },
      "unansweredQuestionIndices": [],
      "answeredAt": "2026-09-16T20:32:48.898Z"
    },
    {
      "sessionId": "21257e30-f7f3-41d2-8147-a93fd5d6d8c6",
      "toolUseId": "toolu_01Kmjiq6KFcms56VBbCZAFEG",
      "questions": [
        {
          "question": "D9 — TODO: capture \"flag-gated shadow compare of the new auth flow against legacyAuthFlow() in production\" for later?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md); D6 approved the characterization suite without the production shadow compare.\nELI10: You chose to prove the rewrite with tests written against the old code. The other half of the idea, running both old and new in production for a while and logging any disagreement, was not taken. This question is only about whether to write that idea down properly so a future session can pick it up with the reasoning intact, not about doing it now.\nStakes if we pick wrong: skip it and the idea evaporates; capture it badly and someone later wonders why it exists.\nRecommendation: A because it costs one paragraph now and is the standard next step if the characterization suite ever misses a production-only token shape.\nNote: options differ in kind, not coverage — no completeness score.\nWhat: flag-gated shadow mode where the new flow runs alongside legacyAuthFlow() for a bounded window; legacy decides; mismatches logged with tenant and case; flag flips after a clean window, then flag and legacy are deleted.\nWhy: catches production-only token shapes and IDP behaviors the characterization suite did not anticipate; makes cutover reversible by config.\nPros: real-traffic proof across all tenants; rollback is a config change.\nCons: temporary flag and compare hook; doubles IDP calls during the window unless the compare reuses the cached result; cleanup task.\nContext: D6 in this review approved characterization tests (10 scenarios) as the regression contract. If the suite passes but any post-cutover incident shows a divergence, this is the next tool. Start at the composition root (D2) where both flows can be constructed side by side.\nDepends on / blocked by: the characterization suite (D6) green against the new flow; legacyAuthFlow() must still exist when shadow mode is added.\nPros / cons:\nA) Add to TODOS.md (recommended)\n  ✅ Idea and its reasoning survive with a clear starting point (composition root) and trigger\n  ✅ Zero implementation cost now; does not change any approved scope\n  ❌ TODOS.md cannot be written in plan mode; content is presented as not persisted until you leave plan mode\nB) Skip — not valuable enough\n  ✅ Keeps the TODO list focused if you are confident the suite is sufficient\n  ✅ Nothing to maintain or clean up later\n  ❌ The reasoning is lost; a future incident re-derives it from scratch\nC) Build it now in this branch\n  ✅ Maximum rollout safety for an auth cutover\n  ✅ The flag and compare hook are small once the composition root exists\n  ❌ Reopens D6's accepted scope and adds a flag and cleanup task to a branch whose goal is a reorganization\nNet: one paragraph of captured reasoning versus nothing.",
          "header": "TODO shadow",
          "multiSelect": false,
          "options": [
            {
              "label": "A) Add to TODOS.md (recommended)",
              "description": "Record the What/Why/Pros/Cons/Context/Depends block above in TODOS.md (presented as not persisted while in plan mode). No implementation now."
            },
            {
              "label": "B) Skip",
              "description": "Do not capture; the idea is dropped from this review's outputs."
            },
            {
              "label": "C) Build it now",
              "description": "Reopen D6 and add the flag-gated shadow compare to this branch's accepted scope; a follow-up decision will re-record R5."
            }
          ]
        }
      ],
      "answered": true,
      "failed": false,
      "answers": {
        "D9 — TODO: capture \"flag-gated shadow compare of the new auth flow against legacyAuthFlow() in production\" for later?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md); D6 approved the characterization suite without the production shadow compare.\nELI10: You chose to prove the rewrite with tests written against the old code. The other half of the idea, running both old and new in production for a while and logging any disagreement, was not taken. This question is only about whether to write that idea down properly so a future session can pick it up with the reasoning intact, not about doing it now.\nStakes if we pick wrong: skip it and the idea evaporates; capture it badly and someone later wonders why it exists.\nRecommendation: A because it costs one paragraph now and is the standard next step if the characterization suite ever misses a production-only token shape.\nNote: options differ in kind, not coverage — no completeness score.\nWhat: flag-gated shadow mode where the new flow runs alongside legacyAuthFlow() for a bounded window; legacy decides; mismatches logged with tenant and case; flag flips after a clean window, then flag and legacy are deleted.\nWhy: catches production-only token shapes and IDP behaviors the characterization suite did not anticipate; makes cutover reversible by config.\nPros: real-traffic proof across all tenants; rollback is a config change.\nCons: temporary flag and compare hook; doubles IDP calls during the window unless the compare reuses the cached result; cleanup task.\nContext: D6 in this review approved characterization tests (10 scenarios) as the regression contract. If the suite passes but any post-cutover incident shows a divergence, this is the next tool. Start at the composition root (D2) where both flows can be constructed side by side.\nDepends on / blocked by: the characterization suite (D6) green against the new flow; legacyAuthFlow() must still exist when shadow mode is added.\nPros / cons:\nA) Add to TODOS.md (recommended)\n  ✅ Idea and its reasoning survive with a clear starting point (composition root) and trigger\n  ✅ Zero implementation cost now; does not change any approved scope\n  ❌ TODOS.md cannot be written in plan mode; content is presented as not persisted until you leave plan mode\nB) Skip — not valuable enough\n  ✅ Keeps the TODO list focused if you are confident the suite is sufficient\n  ✅ Nothing to maintain or clean up later\n  ❌ The reasoning is lost; a future incident re-derives it from scratch\nC) Build it now in this branch\n  ✅ Maximum rollout safety for an auth cutover\n  ✅ The flag and compare hook are small once the composition root exists\n  ❌ Reopens D6's accepted scope and adds a flag and cleanup task to a branch whose goal is a reorganization\nNet: one paragraph of captured reasoning versus nothing.": "A) Add to TODOS.md (recommended)"
      },
      "unansweredQuestionIndices": [],
      "answeredAt": "2026-09-16T20:34:32.512Z"
    },
    {
      "sessionId": "21257e30-f7f3-41d2-8147-a93fd5d6d8c6",
      "toolUseId": "toolu_01U2a6r3wYe8nyH9yH3PWXSe",
      "questions": [
        {
          "question": "D10 — TODO: capture \"single-flight de-duplication of concurrent cache misses in AuthCache.getOrLoad()\" for later?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md); D5 approved getOrLoad as the single miss path.\nELI10: When a tenant's policy version changes, every cached token for that tenant becomes a miss at the same moment, and every in-flight request asks the identity provider separately. Single-flight means the first miss for a key does the IDP call and the others wait for that same answer. It is an existing cost, not something this refactor introduces, but D5 just created the one place where it would be a small change. This question is only about writing it down.\nStakes if we pick wrong: skip and a busy tenant's policy bump keeps producing an IDP burst nobody remembers is avoidable; capture and the fix has an obvious home.\nRecommendation: A because getOrLoad is the right home and the reasoning is cheap to keep; building now would add behavior to a reorganization branch.\nNote: options differ in kind, not coverage — no completeness score.\nWhat: per-key in-flight promise map inside AuthCache.getOrLoad(); concurrent misses for the same key share one loader call; entry cleared on settle.\nWhy: a policy-version bump or cold start for a large tenant turns N concurrent requests into N IDP calls; single-flight makes it 1.\nPros: cuts IDP load and tail latency during invalidation storms; lives in the one approved miss path.\nCons: in-process only (no cross-instance de-dup); must respect the D3 generation guard (a shared result observed before an invalidation must still be dropped); needs a concurrency test.\nContext: D5 approved `AuthCache.getOrLoad(key, loader)` as the single read → miss → load → write path. Add the in-flight map there; the generation check on write already exists (D3). Measure IDP call count during a policy bump before and after.\nDepends on / blocked by: getOrLoad landed (D5); the D8 parallelization commit (to avoid two performance changes in one measurement).\nPros / cons:\nA) Add to TODOS.md (recommended)\n  ✅ Fix has a named home (getOrLoad) and a named trigger (policy-version bump burst) for whoever picks it up\n  ✅ No change to any approved scope on this branch\n  ❌ Not persisted while in plan mode; the IDP burst remains until someone picks it up\nB) Skip — not valuable enough\n  ✅ Keeps the TODO list focused if policy bumps are rare and tenants are small\n  ✅ Nothing to maintain\n  ❌ Existing IDP burst cost stays unrecorded\nC) Build it now in this branch\n  ✅ Small once getOrLoad exists; removes a real burst cost immediately\n  ✅ Concurrency test can share fixtures with the D3 guard test\n  ❌ Adds behavior to a reorganization branch and reopens R4's accepted scope\nNet: one paragraph now versus an unrecorded burst cost.",
          "header": "TODO herd",
          "multiSelect": false,
          "options": [
            {
              "label": "A) Add to TODOS.md (recommended)",
              "description": "Record the What/Why/Pros/Cons/Context/Depends block above in TODOS.md (presented as not persisted while in plan mode). No implementation now."
            },
            {
              "label": "B) Skip",
              "description": "Do not capture; the idea is dropped from this review's outputs."
            },
            {
              "label": "C) Build it now",
              "description": "Reopen D5 and add in-process single-flight to getOrLoad on this branch; a follow-up decision will re-record R4."
            }
          ]
        }
      ],
      "answered": true,
      "failed": false,
      "answers": {
        "D10 — TODO: capture \"single-flight de-duplication of concurrent cache misses in AuthCache.getOrLoad()\" for later?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md); D5 approved getOrLoad as the single miss path.\nELI10: When a tenant's policy version changes, every cached token for that tenant becomes a miss at the same moment, and every in-flight request asks the identity provider separately. Single-flight means the first miss for a key does the IDP call and the others wait for that same answer. It is an existing cost, not something this refactor introduces, but D5 just created the one place where it would be a small change. This question is only about writing it down.\nStakes if we pick wrong: skip and a busy tenant's policy bump keeps producing an IDP burst nobody remembers is avoidable; capture and the fix has an obvious home.\nRecommendation: A because getOrLoad is the right home and the reasoning is cheap to keep; building now would add behavior to a reorganization branch.\nNote: options differ in kind, not coverage — no completeness score.\nWhat: per-key in-flight promise map inside AuthCache.getOrLoad(); concurrent misses for the same key share one loader call; entry cleared on settle.\nWhy: a policy-version bump or cold start for a large tenant turns N concurrent requests into N IDP calls; single-flight makes it 1.\nPros: cuts IDP load and tail latency during invalidation storms; lives in the one approved miss path.\nCons: in-process only (no cross-instance de-dup); must respect the D3 generation guard (a shared result observed before an invalidation must still be dropped); needs a concurrency test.\nContext: D5 approved `AuthCache.getOrLoad(key, loader)` as the single read → miss → load → write path. Add the in-flight map there; the generation check on write already exists (D3). Measure IDP call count during a policy bump before and after.\nDepends on / blocked by: getOrLoad landed (D5); the D8 parallelization commit (to avoid two performance changes in one measurement).\nPros / cons:\nA) Add to TODOS.md (recommended)\n  ✅ Fix has a named home (getOrLoad) and a named trigger (policy-version bump burst) for whoever picks it up\n  ✅ No change to any approved scope on this branch\n  ❌ Not persisted while in plan mode; the IDP burst remains until someone picks it up\nB) Skip — not valuable enough\n  ✅ Keeps the TODO list focused if policy bumps are rare and tenants are small\n  ✅ Nothing to maintain\n  ❌ Existing IDP burst cost stays unrecorded\nC) Build it now in this branch\n  ✅ Small once getOrLoad exists; removes a real burst cost immediately\n  ✅ Concurrency test can share fixtures with the D3 guard test\n  ❌ Adds behavior to a reorganization branch and reopens R4's accepted scope\nNet: one paragraph now versus an unrecorded burst cost.": "A) Add to TODOS.md (recommended)"
      },
      "unansweredQuestionIndices": [],
      "answeredAt": "2026-09-16T20:35:24.836Z"
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      "sessionId": "21257e30-f7f3-41d2-8147-a93fd5d6d8c6",
      "toolUseId": "toolu_01ESRJ8gRPmU62uVYDC83y9U",
      "questions": [
        {
          "question": "D11 — Where next after the engineering review?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md), Eng Review CLEAR, 0 unresolved decisions.\nELI10: The engineering review is done and every decision is locked. You can either go implement the nine tasks now, or first run a CEO-style review that asks whether this refactor is the right thing to spend time on at all (scope, sequencing, business value) before anyone writes code. There is no UI in this plan, so a design review does not apply.\nStakes if we pick wrong: implementing first risks a week of auth work that a strategy pass would have re-sequenced; reviewing first costs one more session before code moves.\nRecommendation: B because the plan author already framed this as a behavior-preserving reorganization with clear engineering value, and the scope was cut at D1 — the remaining risk is execution, not strategy.\nNote: options differ in kind, not coverage — no completeness score.\nPros / cons:\nA) Run /plan-ceo-review first\n  ✅ Independent check that a 9-task auth refactor is the highest-value use of this branch right now\n  ✅ Can re-sequence tasks against product priorities before code is written\n  ❌ Another review session before any code moves; the engineering decisions are already locked\nB) Ready to implement — leave plan mode (recommended)\n  ✅ All ten decisions approved and logged; T1–T9 are ordered with lanes for parallel worktrees\n  ✅ Characterization suite (T1) is the first task, so the regression contract exists before any rewrite\n  ❌ No strategic second opinion; codex outside review was disabled so this was Claude-only\nNet: strategy pass versus starting T1 today.",
          "header": "Next step",
          "options": [
            {
              "label": "B) Ready to implement (recommended)",
              "description": "Leave plan mode; start with T1 (characterization suite) and the two TODOS.md entries."
            },
            {
              "label": "A) /plan-ceo-review first",
              "description": "Run the strategic review on this plan before implementation."
            }
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      "answered": true,
      "failed": false,
      "answers": {
        "D11 — Where next after the engineering review?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md), Eng Review CLEAR, 0 unresolved decisions.\nELI10: The engineering review is done and every decision is locked. You can either go implement the nine tasks now, or first run a CEO-style review that asks whether this refactor is the right thing to spend time on at all (scope, sequencing, business value) before anyone writes code. There is no UI in this plan, so a design review does not apply.\nStakes if we pick wrong: implementing first risks a week of auth work that a strategy pass would have re-sequenced; reviewing first costs one more session before code moves.\nRecommendation: B because the plan author already framed this as a behavior-preserving reorganization with clear engineering value, and the scope was cut at D1 — the remaining risk is execution, not strategy.\nNote: options differ in kind, not coverage — no completeness score.\nPros / cons:\nA) Run /plan-ceo-review first\n  ✅ Independent check that a 9-task auth refactor is the highest-value use of this branch right now\n  ✅ Can re-sequence tasks against product priorities before code is written\n  ❌ Another review session before any code moves; the engineering decisions are already locked\nB) Ready to implement — leave plan mode (recommended)\n  ✅ All ten decisions approved and logged; T1–T9 are ordered with lanes for parallel worktrees\n  ✅ Characterization suite (T1) is the first task, so the regression contract exists before any rewrite\n  ❌ No strategic second opinion; codex outside review was disabled so this was Claude-only\nNet: strategy pass versus starting T1 today.": "B) Ready to implement (recommended)"
      },
      "unansweredQuestionIndices": [],
      "answeredAt": "2026-09-16T20:41:58.524Z"
    }
  ],
  "report": "# Plan: Multi-tenant Auth Refactor — Reviewed Implementation Plan\n\nReviewed target: `PLAN.md` (\"Plan: Multi-tenant Auth Refactor\") in `/tmp/g-6jt867_i/gstack-paid-shard-Lij831/tmp/gstack-plan-count-WtrIYR`, branch `main`, commit `5c885d6`.\nReview: `/plan-eng-review`, 2026-09-16. Evidence base: the plan text only — the repository contains no source or tests, so every finding cites `PLAN.md:line` and marks runtime behavior unknown where the plan does not state it.\n\n## Context\nThe goal is to reorganize existing tenant-auth orchestration without changing\nits product behavior (`PLAN.md:8-9`). The per-request access decision takes\nalready-fetched claims plus tenant/request context and returns allow or deny\nunder the existing access policy; `AuthBroker.validateAndDispatch()` calls it\nafter validation and before dispatch. It adds no policy, network call, cache\nmutation or state (`PLAN.md:9-13`).\n\n## Existing contracts retained (unchanged)\nThe existing cache adapter keys entries by tenant ID, issuer, audience, and\npolicy version. It evicts expired tokens and invalidates entries on logout,\ntoken revocation, or tenant suspension. `AuthCache` retains these validity and\ntenant-key rules unchanged; the adapter does not serialize mutations.\n`AuthCache` is a service-facing facade over that same existing adapter, with\none backing cache. The adapter, its invalidation hooks, and their existing\ntests remain in use unchanged (`PLAN.md:16-22`).\n\n## Architecture (amended by D1)\nStructure chosen at D1 (scope reduced): **3 units**, not 5 classes.\n\n| Unit | Kind | Responsibility |\n|---|---|---|\n| `AuthBroker` | class | `validateAndDispatch()`: validate token, call `decideAccess`, dispatch |\n| `SessionMint` | class | mint/refresh sessions; reads and writes the cache through `AuthCache` |\n| `AuthCache` | class | the one service-facing facade over the existing adapter; absorbs `TokenStore` |\n| `decideAccess(claims, ctx)` | pure function (policy module) | the former `RequestPolicy`; no state, no I/O |\n\n- `RequestPolicy` is not a class: the plan describes it as stateless with no side effects (`PLAN.md:12-13`), so it ships as a pure exported function.\n- `TokenStore` is folded into `AuthCache`: the plan gives it no responsibility distinct from the facade over the one backing cache (`PLAN.md:20-21, 45`). Upgrade trigger: if implementation finds a responsibility the adapter does not own (e.g. refresh-token persistence), split it back out as a plain module and record the reason.\n\n### Wiring (D2, approved)\nOne composition root creates a single `AuthCache(adapter)` and passes it to\n`new AuthBroker(cache, ...)` and `new SessionMint(cache, ...)`. No module-level\nexport of the instance. Tests construct their own `AuthCache` over a fake adapter.\n\n### Concurrent-mutation guard (D3, approved)\n`AuthCache` keeps a per-tenant invalidation generation. Every invalidation hook\n(logout, revocation, suspension) bumps it. `put()` carries the generation\nobserved at read time and is dropped if the tenant's generation has advanced.\nA dropped write degrades to a cache miss (one extra IDP call), never to a stale\nallow. Facade-internal; the adapter is unchanged. Prune a tenant's generation\nentry when the tenant is deleted so the map stays O(active tenants).\n\n### Single miss path (D5, approved)\n`AuthCache.getOrLoad(key, loader)`: read; on miss call `loader`; write through\nthe generation guard. Both `AuthBroker` and `SessionMint` use it; the key rule\n(tenant ID + issuer + audience + policy version) is built in exactly one place.\n\n### Request flow\n```\n request(token, tenantCtx)\n        │\n        ▼\n AuthBroker.validateAndDispatch()\n        │\n        ├─► AuthCache.getOrLoad(key(tenant,issuer,aud,policyVer), loader)\n        │        │ hit ──────────────────────────────► claims\n        │        │ miss ─► loader: IDP validation calls ─► claims\n        │        │                 (5 calls; sequential until the D8 commit,\n        │        │                  then Promise.all fail-fast)\n        │        └─ put(claims, genSeen) ─ dropped if tenant gen advanced (D3)\n        │\n        ├─► decideAccess(claims, tenantCtx)   pure; allow | deny\n        │\n        ├─ allow ─► dispatch(request)\n        └─ deny  ─► explicit deny outcome\n   any throw ─► single catch: error map (D4)\n                 ValidationError  → deny 401 + log{tenant,reqId}\n                 PolicyDenied     → deny 403 + log\n                 IdpUnavailable   → 503 retryable + log\n                 unknown          → deny + re-throw + log\n\n SessionMint.mint()/refresh() ─► AuthCache.getOrLoad(...) (same path, same guard)\n\n invalidation hooks (logout | revoke | suspend tenant)\n        └─► adapter.invalidate(...)  +  AuthCache.bumpGeneration(tenant)\n```\n\n## Code quality (D4, approved)\n`validateAndDispatch()` becomes a linear validate → decideAccess → dispatch\ninside one `try`; a single `catch` maps each known error class to an explicit\noutcome and a structured log line carrying tenant ID and request ID. Unknown\nerrors deny and re-throw. Deny-by-default is the contract: nothing reaches\ndispatch after a failed validation. Table-driven unit test, one row per error\nclass. Existing ASCII diagrams in touched files (unknown until source is open)\nmust be checked and updated in the same commit.\n\n## Tests (D6 and D7, approved)\n**Regression contract (IRON RULE).** Before any rewrite, write a\ncharacterization suite against `legacyAuthFlow()` covering: valid token,\nexpired, revoked, logged-out, suspended tenant, cross-tenant token,\npolicy-version bump, malformed token, IDP unavailable, IDP timeout. Assert the\noutcome class and the resulting cache state. The new flow must pass the same\nsuite. Intentional differences are only D4's explicit deny where legacy\nswallowed an error; each such case is listed and asserted as an intentional\nchange. Nothing else may differ. Shadow compare in production was not approved\n(captured as TODO 1).\n\n**Two-tenant E2E** against a fake IDP: tenants A and B log in, validate,\n`decideAccess` and dispatch; a cross-tenant token is rejected; suspending A\nmid-session denies A's next request and leaves B untouched; IDP outage yields\nthe explicit 503 path; a policy-version bump forces a re-validate.\n\n**Common-work proof of retained contracts** (`PLAN.md:16-22`, no separate\napproval): tenant-key isolation through the facade; logout, revocation and\nsuspension propagate through `AuthCache`, not just the adapter.\n\n**Carried with approved remedies:** D3 deterministic concurrency test (write\nstarted before invalidation is dropped); D4 table-driven error-map test; D5\n`getOrLoad` hit / miss / loader-throws tests.\n\nTest framework: unknown (repository holds no manifest or test files; CLAUDE.md\nhas no Testing section). Match whatever the auth package already uses; do not\nintroduce a new runner for this work.\n\n## Performance (D8, approved)\nThe 5 IDP calls stay sequential through the refactor. `Promise.all` lands as\nits own final commit on this branch after the characterization suite is green\nagainst the new flow. Preconditions: a bounded probe confirms no call consumes\nanother call's output and the IDP tolerates 5 concurrent calls per validation;\nfail-fast semantics with the first rejection routed through the D4 error map;\nbefore/after validation latency recorded in the PR. The policy-version-bump\nmiss storm is existing behavior; single-flight de-dup is captured as TODO 2.\n\n## Implementation order\n1. Characterization suite against `legacyAuthFlow()` (must be green on legacy before step 8).\n2. `decideAccess(claims, ctx)` pure function + table-driven tests.\n3. `AuthCache` facade: key rule, generation guard, `getOrLoad`, invalidation-hook bumps, concurrency test, isolation/propagation tests.\n4. `AuthBroker.validateAndDispatch()` rewrite with the error map + tests.\n5. `SessionMint` on `getOrLoad` + tests.\n6. Composition root: single `AuthCache` wiring; rewire callers of `legacyAuthFlow()`.\n7. Two-tenant E2E with fake IDP.\n8. Run the characterization suite against the new flow; list intentional D4 differences; delete `legacyAuthFlow()`.\n9. Final commit: `Promise.all` after the independence and rate-limit probe; record latency.\n\n---\n\n# Review output\n\n## Step 0: Scope Challenge — findings\nDisposition: **scope reduced per recommendation** (D1: 3 units instead of 5 classes).\n\n| # | Sev | Conf | Source | Finding | Disposition |\n|---|---|---|---|---|---|\n| S1 | P2 | 8/10 | `PLAN.md:44-45` | 12 files, 5 new classes for a behavior-preserving refactor; `RequestPolicy` is stateless (`PLAN.md:12-13`) and `TokenStore` has no stated responsibility distinct from `AuthCache` (`PLAN.md:20-21`) | accepted: D1 → 3 units |\n| S2 | P3 | 7/10 | `PLAN.md:8-9` vs `PLAN.md:40-41` | plan mixes a behavior change (parallelization) into a \"no behavior change\" refactor | accepted: D8 → separate final commit |\n| S3 | — | — | — | Search check: unavailable (no Aside, no WebSearch) — proceeded with in-distribution knowledge; **[Layer 1]** patterns used throughout: constructor injection, compare-and-set generation guard, characterization tests, get-or-load helper | noted |\n| S4 | — | — | — | TODOS.md: absent; nothing blocking | noted |\n| S5 | — | — | — | Distribution: N/A, no new artifact | noted |\n\n## Section 1: Architecture — findings\n| # | Sev | Conf | Source | Finding | Disposition |\n|---|---|---|---|---|---|\n| A1 | P1 | 9/10 | `PLAN.md:28-29` | module-level mutable `AuthCache` singleton shared by two services: hidden coupling, cross-test state leakage, no composition root | accepted: D2 constructor injection |\n| A2 | P1 | 7/10 | `PLAN.md:19`, `PLAN.md:29` | unserialized mutations from two writers: a mint write racing a suspension/revocation/logout invalidation resurrects access until expiry, silently | accepted: D3 generation guard |\n| A3 | P2 | 8/10 | `PLAN.md:11-13` | no stated behavior when validation throws before `decideAccess`; deny-by-default not specified | accepted: folded into D4 |\n| A4 | P2 | 6/10 | `PLAN.md:16-17` | facade must not permit lookups without tenant ID or cross-tenant hits (medium confidence, verify) | common work: contract proof tests (Tests section) |\n| A5 | P3 | 9/10 | whole plan | no data-flow diagram for validate → decide → dispatch → cache | factual addition: Request flow diagram above |\n\nProduction failure scenarios per new codepath are in Failure modes below.\n\n## Section 2: Code quality — findings\n| # | Sev | Conf | Source | Finding | Disposition |\n|---|---|---|---|---|---|\n| C1 | P1 | 9/10 | `PLAN.md:32-33` | three nested try/catch blocks each swallowing an error class in the access-granting function | accepted: D4 explicit error map |\n| C2 | P2 | 6/10 | `PLAN.md:29` | read → miss → IDP → write sequence duplicated across both services (medium confidence, inferred) | accepted: D5 `getOrLoad` |\n| C3 | P3 | 8/10 | whole plan | no inline diagrams planned for `AuthCache` (generation state) or `validateAndDispatch()` (pipeline) | factual addition: Diagrams section below |\n\n## Section 3: Test review — coverage diagram\nNothing in this plan exists yet; every planned path is a gap with an approved test (D3–D7). The only existing coverage is the adapter's own suite (`PLAN.md:21-22`), which remains in use; its quality is unverified from here.\n\n```\nCODE PATHS                                                   USER FLOWS\n[+] auth/broker  AuthBroker.validateAndDispatch()            [+] Two-tenant login → dispatch\n  ├── [GAP] happy: validate → allow → dispatch      (D4)       ├── [GAP] [→E2E] A and B both succeed, no cross-talk   (D7)\n  ├── [GAP] ValidationError → deny 401              (D4)       ├── [GAP] [→E2E] A's token in B's context → denied     (D7)\n  ├── [GAP] PolicyDenied → deny 403                 (D4)       ├── [GAP] [→E2E] suspend A mid-session → A denied, B ok (D7)\n  ├── [GAP] IdpUnavailable → 503 retryable          (D4)       └── [GAP] [→E2E] policy bump → re-validate, then cached (D7)\n  ├── [GAP] unknown error → deny + re-throw         (D4)     [+] Replay after invalidation\n  └── [GAP] legacy-swallowed cases asserted changed (D6)       ├── [GAP] logout then replay → denied                  (D6)\n[+] auth/policy  decideAccess(claims, ctx)                     └── [GAP] revoke then replay → denied                  (D6)\n  └── [GAP] table: allow / deny / missing claims /           [+] Error states the user sees\n            tenant mismatch                          (D2 tests)  ├── [GAP] [→E2E] IDP outage → explicit 503, not silent (D4/D7)\n[+] auth/cache  AuthCache                                      ├── [GAP] IDP timeout on one call → explicit failure    (D6)\n  ├── [GAP] key = tenant+issuer+aud+policyVer        (common)   ├── [GAP] malformed / wrong issuer / wrong aud → deny  (D6)\n  ├── [GAP] cross-tenant isolation                   (common)   └── [GAP] expired token → same class as legacy         (D6)\n  ├── [GAP] hooks bump generation (3 hooks)          (D3)     [+] Concurrency\n  ├── [GAP] put dropped when generation advanced     (D3)       └── [GAP] two logins same tenant → both ok, one entry  (D3)\n  ├── [GAP] getOrLoad hit                            (D5)\n  ├── [GAP] getOrLoad miss → load → write            (D5)\n  └── [GAP] getOrLoad loader throws → no write       (D5)\n[+] auth/session  SessionMint\n  └── [GAP] mint / refresh / IDP failure             (plan)\n[+] composition root\n  └── [GAP] single AuthCache instance wired          (D2; proven by E2E)\n[+] idp parallel validation (final commit)\n  └── [GAP] all succeed / first rejection fail-fast / timeout  (D8)\n[~] existing adapter eviction + invalidation  [TESTED existing, quality unverified — PLAN.md:21-22]\n\nCOVERAGE: 1/27 paths tested today (4%)  |  Code paths: 1/16  |  User flows: 0/11\nQUALITY: existing adapter suite unverified  |  GAPS: 26 (5 E2E, 0 eval) — all 26 have an approved test in the plan\n```\nLegend: [GAP] = no test exists today; parenthetical = approving decision. [→E2E] = integration test. No LLM/eval scope in this plan.\n\nTest findings: T1 [P1] (9/10) `PLAN.md:36-37` regression coverage absent → D6 (accepted). T2 [P2] (8/10) `PLAN.md:23-24` no cross-unit scenario → D7 (accepted).\nTest Plan Artifact written: `~/.gstack/projects/gstack-plan-count-WtrIYR/vercel-sandbox-main-eng-review-test-plan-20260916-203316.md`.\n\n## Section 4: Performance — findings\n| # | Sev | Conf | Source | Finding | Disposition |\n|---|---|---|---|---|---|\n| P1 | P2 | 7/10 | `PLAN.md:40-41` | 5 sequential IDP calls; `Promise.all` proposed on an unverified independence claim inside a no-behavior-change refactor | accepted: D8 separate final commit with probe |\n| P2 | P3 | 8/10 | `PLAN.md:16-17` | policy-version bump = full miss storm for the tenant against the IDP (existing behavior) | TODO 2 (D10) |\n\nN+1/database access: none in scope. Memory: generation map O(active tenants), pruned on tenant deletion.\n\n## Outside Voice\nCodex review skipped (`codex_reviews` disabled). Recorded `outside_status: disabled`; no native replacement per the disabled branch. Re-enable: `gstack-config set codex_reviews enabled`.\n\n## NOT in scope\n- Production shadow compare of new vs legacy flow — declined at D6; captured as TODO 1.\n- Single-flight de-duplication of concurrent misses — existing cost, not introduced here; TODO 2.\n- Changing the adapter's key rule, eviction or invalidation semantics — retained contracts (`PLAN.md:16-22`).\n- Any policy change inside `decideAccess` — the function groups the existing decision only (`PLAN.md:9-13`).\n- Cross-instance cache coordination — the generation guard is in-process; the adapter's own semantics cover the rest.\n- Distribution/CI changes — no new artifact.\n\n## What already exists\n| Existing | Plan reuses? |\n|---|---|\n| Cache adapter: tenant/issuer/audience/policy-version keys, expiry eviction, logout/revocation/suspension invalidation, its tests (`PLAN.md:16-22`) | Yes, unchanged; `AuthCache` is a facade over it. Generation guard is added in the facade, not the adapter. |\n| Existing per-request access decision (`PLAN.md:9-13`) | Yes, moved verbatim into `decideAccess`. |\n| `legacyAuthFlow()` (`PLAN.md:36`) | Rewritten; its behavior is captured first by the characterization suite (D6) and it is deleted only after the suite passes on the new flow. |\n| Existing IDP validation calls (`PLAN.md:40`) | Yes, wrapped as the `getOrLoad` loader; parallelized only in the final commit. |\n| `TokenStore` (proposed, `PLAN.md:45`) | Not built — folded into `AuthCache` (D1). |\n\n## Diagrams\n- Plan: Request flow diagram above (keep it in the plan and in the PR description).\n- `auth/cache/AuthCache` header comment: generation-guard state diagram (`gen[tenant]` bump on each hook; `put(genSeen)` accepted iff `genSeen == gen[tenant]`).\n- `auth/broker/AuthBroker.validateAndDispatch()` header comment: the linear pipeline and error-map table.\n- `auth/policy/decideAccess` header comment: decision table inputs → allow/deny.\n- Check touched files for existing diagrams and update in the same commit.\n\n## Failure modes\n| Codepath | Realistic failure | Test | Handling | User sees | Critical gap? |\n|---|---|---|---|---|---|\n| `validateAndDispatch` validation | IDP 5xx / network timeout | D4 table row, D6 IDP unavailable/timeout, D7 outage | error map → 503 retryable + log | clear retryable error | no |\n| `validateAndDispatch` unknown throw | new error class from a dependency | D4 unknown row | deny + re-throw + log | explicit deny; alert via log | no |\n| `decideAccess` | missing/malformed claims | D2-era table test | pure deny | 403 | no |\n| `AuthCache.put` race | mint write after suspension | D3 concurrency test | generation guard drops write | one extra IDP call | no |\n| `AuthCache.getOrLoad` | loader throws | D5 loader-throws test | no write, error propagates to error map | explicit error | no |\n| composition root | two `AuthCache` instances constructed | D7 E2E (suspension propagates) | single construction site | n/a | no |\n| `legacyAuthFlow` rewrite | outcome drift | D6 characterization suite | n/a (test gate) | none if suite passes | no |\n| `Promise.all` commit | one call depends on another; IDP rate limit | D8 probe + tests | fail-fast through error map | 503 retryable | no |\n| generation map | unbounded growth | implementation note (prune on tenant delete) | prune | n/a | no |\n\n**Critical gaps: 0** in the accepted plan (every failure mode has a planned test and explicit handling). All of this is planned, not existing; the gaps close only when the tasks below land.\n\n## Worktree parallelization strategy\n| Step | Modules touched | Depends on |\n|---|---|---|\n| 1 Characterization suite | test/ (legacy flow) | — |\n| 2 decideAccess | auth/policy/ | — |\n| 3 AuthCache facade | auth/cache/ | — |\n| 4 AuthBroker rewrite | auth/broker/ | 2, 3 |\n| 5 SessionMint | auth/session/ | 3 |\n| 6 Composition root + caller rewiring | auth/ (root), app bootstrap | 4, 5 |\n| 7 Two-tenant E2E | test/e2e/ | 6 |\n| 8 Suite vs new flow; delete legacy | test/, auth/ | 1, 6 |\n| 9 Promise.all commit | auth/broker/ (loader) | 8 |\n\nLanes: `Lane A: 1 (independent)` / `Lane B: 2 (independent)` / `Lane C: 3 → 5 (sequential, shared auth/cache/ consumer)` / `Lane D: 4 → 6 → 7 → 8 → 9 (sequential)`.\nExecution order: launch A, B, C in parallel worktrees. Merge all three. Then D.\nConflict flags: steps 4 and 9 both touch auth/broker/ — kept sequential in Lane D. Step 6 touches app bootstrap that other in-flight branches may also edit; coordinate.\n\n## Implementation Tasks\nSynthesized from this review's findings. Each task derives from a specific\nfinding above. Run with Claude Code or Codex; checkbox as you ship.\n\n- [ ] **T1 (P1, human: ~1.5 days / CC: ~30 min)** — test/ — Write the characterization suite against `legacyAuthFlow()` (10 scenarios, outcome class + cache state) before any rewrite\n  - Surfaced by: Test review — T1, `PLAN.md:36-37` \"no regression test for the prior behavior is planned\" (D6)\n  - Files: test/auth/legacy-characterization.<ext>, fake IDP fixture\n  - Verify: suite green against legacy; later green against new flow with only listed D4 differences\n- [ ] **T2 (P1, human: ~1 day / CC: ~20 min)** — auth/cache/ — Build `AuthCache` facade: key rule, per-tenant generation guard, hook bumps, `getOrLoad`\n  - Surfaced by: Architecture A2 (D3), Code quality C2 (D5), A4 common work\n  - Files: auth/cache/AuthCache.<ext>, auth/cache/AuthCache.test.<ext>\n  - Verify: concurrency test (write started before invalidation is dropped); getOrLoad hit/miss/throws; cross-tenant isolation; hook propagation\n- [ ] **T3 (P1, human: ~4h / CC: ~15 min)** — auth/broker/ — Rewrite `validateAndDispatch()` as linear flow with single error map, deny-by-default, structured logs\n  - Surfaced by: Code quality C1, `PLAN.md:32-33` (D4); Architecture A3\n  - Files: auth/broker/AuthBroker.<ext>, auth/broker/AuthBroker.test.<ext>\n  - Verify: table-driven test, one row per error class incl. unknown → deny + re-throw\n- [ ] **T4 (P1, human: ~2h / CC: ~10 min)** — auth/ root — Composition root: single `AuthCache(adapter)` injected into `AuthBroker` and `SessionMint`; remove module-level export\n  - Surfaced by: Architecture A1, `PLAN.md:28-29` (D2)\n  - Files: auth/index.<ext> (or app bootstrap), call sites of legacyAuthFlow\n  - Verify: grep shows one `new AuthCache(`; E2E suspension propagates to both services\n- [ ] **T5 (P1, human: ~1 day / CC: ~20 min)** — test/e2e/ — Two-tenant E2E against fake IDP (cross-tenant, suspension mid-session, outage, policy bump)\n  - Surfaced by: Test review T2, `PLAN.md:23-24` (D7)\n  - Files: test/e2e/auth-two-tenant.<ext>, fake IDP fixture (shared with T1)\n  - Verify: all four scenarios pass deterministically, no network\n- [ ] **T6 (P2, human: ~3h / CC: ~10 min)** — auth/policy/ — Extract `decideAccess(claims, ctx)` as a pure function with table-driven tests\n  - Surfaced by: Scope Challenge S1, `PLAN.md:12-13` (D1)\n  - Files: auth/policy/decideAccess.<ext>, auth/policy/decideAccess.test.<ext>\n  - Verify: allow / deny / missing claims / tenant mismatch rows\n- [ ] **T7 (P2, human: ~4h / CC: ~15 min)** — auth/session/ — `SessionMint` on `getOrLoad`; mint / refresh / IDP-failure tests\n  - Surfaced by: Architecture (D1 structure), Code quality C2 (D5)\n  - Files: auth/session/SessionMint.<ext>, auth/session/SessionMint.test.<ext>\n  - Verify: no direct adapter access; all writes go through getOrLoad\n- [ ] **T8 (P2, human: ~half day / CC: ~15 min)** — auth/broker/ — Final commit: probe call independence + IDP concurrency limit, then `Promise.all` fail-fast; record latency before/after\n  - Surfaced by: Performance P1, `PLAN.md:40-41` (D8)\n  - Files: auth/broker/ loader, PR description\n  - Verify: characterization suite still green; latency numbers in PR\n- [ ] **T9 (P2, human: ~1h / CC: ~5 min)** — auth/ — Inline ASCII diagrams in `AuthCache`, `validateAndDispatch()`, `decideAccess`; update any existing diagrams in touched files\n  - Surfaced by: Architecture A5, Code quality C3\n  - Files: headers of the three modules\n  - Verify: diagrams match the shipped code in the same commit\n\nEstimate assumption: tests ~50x, architecture ~5x, bug fix ~20x human ÷ CC ratios, adjusted for a security-sensitive path where verification dominates.\n\n## TODOS.md updates (not persisted — repo write forbidden in plan mode; add on leaving plan mode)\n**TODO 1 — Flag-gated shadow compare of new auth flow vs `legacyAuthFlow()` in production** (D9: add)\n- What: flag-gated shadow mode; legacy decides; new flow runs alongside; mismatches logged with tenant and case; flag flips after a clean window; flag and legacy deleted afterwards.\n- Why: catches production-only token shapes/IDP behaviors the characterization suite did not anticipate; cutover reversible by config.\n- Pros: real-traffic proof across tenants; rollback = config change.\n- Cons: temporary flag and compare hook; doubles IDP calls during the window unless it reuses the cached result; cleanup task.\n- Context: D6 approved the 10-scenario characterization suite as the regression contract. If a post-cutover incident shows divergence, this is the next tool. Start at the composition root (D2) where both flows can be constructed side by side.\n- Depends on / blocked by: T1 green against the new flow; `legacyAuthFlow()` still present when shadow mode is added (so do this before step 8 deletes it, or keep a copy).\n\n**TODO 2 — Single-flight de-duplication in `AuthCache.getOrLoad()`** (D10: add)\n- What: per-key in-flight promise map; concurrent misses for one key share one loader call; entry cleared on settle.\n- Why: a policy-version bump or cold start for a large tenant turns N concurrent requests into N IDP calls.\n- Pros: cuts IDP load and tail latency during invalidation storms; lives in the one approved miss path.\n- Cons: in-process only; must respect the D3 generation guard; needs a concurrency test.\n- Context: D5 approved `getOrLoad` as the single miss path; the generation check on write already exists (D3). Measure IDP call count during a policy bump before/after.\n- Depends on / blocked by: T2 landed; T8 landed (avoid two performance changes in one measurement).\n\n## Unresolved decisions that may bite you later\nNone — D1 through D10 all answered.\n\n## Suppressed findings (confidence ≤ 4)\n- (3/10) `SessionMint` may need refresh-token persistence the adapter does not model — this would be the trigger to re-split `TokenStore` (D1 upgrade trigger). No plan line to quote; unverified.\n- (3/10) `decideAccess` may need the policy version as an input to stay pure across a bump — depends on how the existing decision reads policy; unverified.\n\n## Completion summary\n- Step 0: Scope Challenge — scope reduced per recommendation (D1: 3 units, not 5 classes)\n- Architecture Review: 5 issues found (A1–A5)\n- Code Quality Review: 3 issues found (C1–C3)\n- Test Review: diagram produced, 26 gaps identified (all with approved tests; 2 findings T1–T2)\n- Performance Review: 2 issues found (P1–P2)\n- NOT in scope: written\n- What already exists: written\n- TODOS.md updates: 2 items proposed to user (both accepted; not persisted in plan mode)\n- Failure modes: 0 critical gaps flagged\n- Unresolved decisions: 0 in this review\n- Outside voice: codex, disabled (codex_reviews=disabled; recorded, no native replacement)\n- Parallelization: 4 lanes, 3 parallel / 1 sequential\n- Lake Score: 4/5 (D3, D4, D5, D7 chose 10/10; D6 chose 9/10)\n\n## Decision ledger\n\n### R0: Complexity gate — class/module arrangement (Scope Challenge)\nFinding: Scope Challenge S1, P2, confidence 8/10, `PLAN.md:44-45` (\"touches 12 files and introduces 5 new classes\"), reviewer: Claude (plan-eng-review).\nPlan baseline: original proposal — 5 classes (AuthBroker, TokenStore, SessionMint, AuthCache, RequestPolicy) across 12 files.\nRuntime evidence: none — no source in repository; the plan's own text describes RequestPolicy as stateless (`PLAN.md:12-13`) and gives TokenStore no responsibility.\nQuestion D1: Complexity gate: 5 new classes for a behavior-preserving refactor, or fewer? Options A) 3 units (recommended), B) 4 units, C) Original 5 classes. Structure only; all other remedies stayed pending.\nState: approved\nActual answer: A) 3 units (recommended) — user answer to D1.\nAccepted scope: AuthBroker, SessionMint, AuthCache as classes; RequestPolicy becomes pure function `decideAccess(claims, ctx)`; TokenStore folds into AuthCache. No other remedy approved by this answer.\nHistory: none.\n\n### R1: AuthCache wiring — how AuthBroker and SessionMint obtain the shared instance\nFinding: A1, P1, confidence 9/10, `PLAN.md:28-29` (\"share a global mutable `AuthCache` instance via module-level export. Both services mutate it.\"), reviewer: Claude (plan-eng-review).\nPlan baseline: original proposal — module-level exported singleton imported by both services.\nRuntime evidence: unknown — no source in repository.\nComparison grid:\n\n| Choice | Current | A | B | C |\n|---|---|---|---|---|\n| R1 AuthCache wiring | module-level export, both services import it | constructor injection of one instance from a composition root; no module-level export | module-level export kept as planned | module-level export kept, plus `resetForTests()` hook |\n| R2 write-after-invalidate guard | unspecified, pending | pending | pending | pending |\n| R0 structure (approved D1) | 3 units | 3 units | 3 units | 3 units |\n\nQuestion D2:\nD2 — How should AuthBroker and SessionMint get the shared AuthCache: injected, or a module-level global?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md); D1 fixed the structure at 3 units (AuthBroker, SessionMint, AuthCache + decideAccess function).\nELI10: Right now the plan has one cache object living at the top of a module, and both services reach out and grab it. That works until you want to test one service alone, run two tenants' worth of fixtures in one test file, or swap the cache backend: every test shares the same hidden object and leaks state into the next one. Handing the cache in through the constructor makes the dependency visible and gives you one obvious place (the composition root) where the single instance is created.\nStakes if we pick wrong: with the global, a flaky test suite and a cache that cannot be replaced without editing the module; with injection done sloppily, two call sites accidentally construct two AuthCache instances over one adapter and invalidation only hits one.\nRecommendation: A because a security-sensitive cache should have exactly one construction site and every consumer should declare it; this is the explicit-over-clever preference with almost no extra effort (human: ~2h / CC: ~10 min).\nNote: options differ in kind, not coverage — no completeness score.\nThis decides wiring only. The write-after-invalidate guard (R2) is asked next; structure stays at D1's 3 units.\nPros / cons:\nA) Constructor injection from one composition root (recommended)\n  ✅ Each service declares its cache dependency; unit tests construct a fresh AuthCache over a fake adapter per test\n  ✅ Exactly one `new AuthCache(adapter)` call site, so the \"one backing cache\" contract (PLAN.md:21) is enforced by construction\n  ❌ Every place that instantiates AuthBroker or SessionMint must pass the cache; a handful of call sites change\nB) Module-level export as planned\n  ✅ Zero wiring changes; matches the plan text exactly and is the fastest path to a green build\n  ✅ Guarantees a single instance by module semantics without a composition root\n  ❌ Hidden coupling and cross-test state leakage; replacing the adapter means editing the module, not the wiring\nC) Module-level export plus an explicit `resetForTests()` hook\n  ✅ Keeps the plan's import-and-use ergonomics while giving tests a way to clear shared state\n  ✅ Smallest change that addresses the test-isolation symptom\n  ❌ Test-only hooks in production auth code are a smell; the dependency is still invisible at the call site\nNet: trading a few constructor-signature edits against a hidden global in the codepath that decides who gets into which tenant.\nHeader: Cache wiring\nOptions:\nA) Constructor injection (recommended)\nOne composition root creates a single `AuthCache(adapter)` and passes it to `new AuthBroker(cache, ...)` and `new SessionMint(cache, ...)`. No module-level export of the instance. Tests construct their own AuthCache over a fake adapter. Wiring only; R2 guard stays pending.\nB) Module-level export\nKeep the plan as written: `AuthCache` instance exported from its module and imported by both services. Wiring only; R2 guard stays pending.\nC) Module global + resetForTests()\nKeep the module-level export and add an explicit `resetForTests()` that swaps or clears the shared instance for test isolation. Wiring only; R2 guard stays pending.\n\nState: approved\nActual answer: A) Constructor injection (recommended) — user answer to D2.\nAccepted scope: One composition root creates a single `AuthCache(adapter)` and passes it to `new AuthBroker(cache, ...)` and `new SessionMint(cache, ...)`; no module-level export of the instance; tests construct their own AuthCache over a fake adapter. Wiring only; R2 guard remains pending; structure stays at D1's 3 units.\nHistory: none.\n\n### R2: Write-after-invalidate guard for concurrent AuthCache mutation\nFinding: A2, P1, confidence 7/10, `PLAN.md:19` (\"they do not serialize mutations\") with `PLAN.md:29` (\"Both services mutate it.\"), reviewer: Claude (plan-eng-review).\nPlan baseline: original proposal — both services write to the shared cache directly; no ordering guarantee between a write and an invalidation hook (logout, revocation, tenant suspension).\nRuntime evidence: unknown — no source; whether legacyAuthFlow already had two concurrent writers is not stated.\nComparison grid:\n\n| Choice | Current | A | B | C |\n|---|---|---|---|---|\n| R2 write-after-invalidate guard | none specified | AuthCache tracks a per-tenant invalidation generation; `put()` is a compare-and-set that drops a write whose read generation is stale | no guard; both services write directly as planned | bounded probe of the existing adapter for ordering guarantees before choosing; no implementation approved |\n| R1 wiring (approved D2) | constructor injection | constructor injection | constructor injection | constructor injection |\n| R0 structure (approved D1) | 3 units | 3 units | 3 units | 3 units |\n\nQuestion D3:\nD3 — Should AuthCache refuse a cache write that started before an invalidation for the same tenant?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md); D1 fixed 3 units, D2 fixed constructor injection of one AuthCache.\nELI10: Two services write into the same cache and the plan says nothing serializes those writes. Picture tenant T getting suspended: the invalidation hook wipes T's entries, but SessionMint was already halfway through minting a session for T and writes a fresh entry a few milliseconds later. That entry survives until it expires, so a suspended tenant keeps getting in. The fix is a small stamp: each tenant has an invalidation counter, a write remembers the counter it saw when it started, and the cache drops the write if the counter moved.\nStakes if we pick wrong: without the guard, logout, revocation and suspension can be silently undone by a racing write and nobody sees an error; with the guard done wrong, legitimate writes get dropped and users see extra IDP round trips (a cache miss, not a lockout).\nRecommendation: A because the failure is silent, security-relevant, and the guard is a few lines inside the one facade that D1 and D2 just made the single write path (human: ~1 day incl. tests / CC: ~20 min).\nCompleteness: A=10/10, B=3/10, C=n/a (investigation only, no remedy)\nPros / cons:\nA) Per-tenant invalidation generation with compare-and-set writes in AuthCache (recommended)\n  ✅ Suspension, revocation and logout cannot be resurrected by a racing mint or validation write; the invariant lives in one place\n  ✅ Failure mode degrades to a cache miss (one extra IDP call), never to a wrongly cached allow\n  ❌ Adds state to the facade (a generation map) and a deterministic concurrency test that must be written carefully\nB) No guard; both services write directly as planned\n  ✅ Smallest diff; keeps the facade a thin pass-through over the adapter exactly as PLAN.md:20-21 describes\n  ✅ If the legacy flow already had this race, this option does not make anything worse than today\n  ❌ A suspended or logged-out tenant can retain cached access until expiry with no log line; silent security regression risk\nC) Investigate first: bounded probe of the existing adapter's ordering guarantees, then decide\n  ✅ Avoids building a guard the adapter may already provide (e.g. versioned keys or invalidate-then-fence semantics)\n  ✅ Cheap: read the adapter and its invalidation tests, report what ordering exists (CC: ~5 min once source is available)\n  ❌ Leaves the race unresolved in the plan until the probe runs; implementation must not start this seam before the follow-up answer\nNet: trading a small generation map and one concurrency test against a silent way for revoked access to come back.\nHeader: Cache race\nOptions:\nA) Generation guard (recommended)\nAuthCache keeps a per-tenant invalidation generation; every invalidation hook (logout, revocation, suspension) bumps it; `put()` carries the generation observed at read time and is dropped if the tenant's generation has advanced. Includes the deterministic concurrency test. Applies inside the facade only.\nB) No guard\nBoth services write to AuthCache directly with no ordering check, as the plan describes. Race is recorded as an accepted risk in the report.\nC) Investigate first\nBounded probe of the existing adapter and its invalidation tests for ordering guarantees before choosing. Approves no implementation; the guard choice stays pending for a follow-up answer.\n\nState: approved\nActual answer: A) Generation guard (recommended) — user answer to D3.\nAccepted scope: AuthCache keeps a per-tenant invalidation generation; every invalidation hook (logout, revocation, suspension) bumps it; `put()` carries the generation observed at read time and is dropped if the tenant's generation has advanced; includes the deterministic concurrency test. Facade-internal only; adapter unchanged. R0 and R1 values unchanged.\nHistory: none.\n\n### R3: validateAndDispatch() error handling\nFinding: C1, P1, confidence 9/10, `PLAN.md:32-33` (\"60 lines with three nested try/catch blocks; each catch swallows a different error class\"), reviewer: Claude (plan-eng-review).\nPlan baseline: original proposal — function kept as described; no change planned.\nRuntime evidence: unknown — no source; the plan's own description is the evidence.\nComparison grid:\n\n| Choice | Current | A | B | C |\n|---|---|---|---|---|\n| R3 error handling in validateAndDispatch | 3 nested try/catch, each swallows one error class | one linear flow (validate → decideAccess → dispatch) with a single catch that maps each error class to an explicit outcome; deny-by-default; nothing swallowed; structured log per outcome | keep 3 nested blocks, but each catch logs and returns an explicit deny instead of swallowing | keep as described (swallowing) |\n| R0 / R1 / R2 (approved) | — | unchanged | unchanged | unchanged |\n\nQuestion D4:\nD4 — How should validateAndDispatch() handle errors: one explicit error map, or keep the nested try/catch?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md); structure, wiring and the cache guard are fixed (D1–D3).\nELI10: The function that decides whether a request gets in has three try/catch blocks nested inside each other, and each one quietly eats a different kind of error. When an error is eaten, the code after it keeps running as if nothing went wrong, so a failed token check can fall through to dispatch, or fail with no log line to explain a locked-out user. The fix is to make the flow a straight line (validate, decide, dispatch) and have one place that says, for each error type, exactly what the caller gets back and what gets logged.\nStakes if we pick wrong: a swallowed validation error can become an allow (security), and a swallowed IDP outage becomes a silent lockout with no log to debug at 3am.\nRecommendation: A because deny-by-default with an explicit error map is the smallest change that makes every failure path both safe and visible; it also drops the function well under 60 lines (human: ~4h / CC: ~15 min).\nCompleteness: A=10/10, B=6/10, C=2/10\nPros / cons:\nA) Linear flow with one explicit error map, deny-by-default, structured logs (recommended)\n  ✅ Every error class has a named outcome (e.g. ValidationError → deny 401, PolicyDenied → deny 403, IdpUnavailable → 503 + retryable) and a log line with tenant and request IDs\n  ✅ Unknown errors deny and re-throw, so nothing new can slip through to dispatch; table-driven tests cover each row\n  ❌ Callers that relied on a swallowed error producing a soft result may see a new explicit deny; the regression suite must catch this\nB) Keep the nested blocks; each catch logs and returns an explicit deny\n  ✅ Minimal structural change to a function the team already knows\n  ✅ Stops the silent-swallow behavior, which is the most dangerous part\n  ❌ Still 60 lines and three nesting levels; the outcome for each error class is spread across the function instead of one table\nC) Keep as described: nested blocks that swallow\n  ✅ Zero risk of changing any caller-visible behavior in this refactor\n  ✅ No new tests required for this function beyond what the plan already lists\n  ❌ Errors keep disappearing in the codepath that grants access; incompatible with the \"explicit over clever\" preference\nNet: trading a small chance that a caller depended on a swallowed error against silent failures in the access-granting path.\nHeader: Error handling\nOptions:\nA) Explicit error map (recommended)\nRewrite validateAndDispatch() as validate → decideAccess → dispatch inside one try; a single catch maps each known error class to an explicit outcome and structured log; unknown errors deny and re-throw. Table-driven unit test per error class.\nB) Log-and-deny in each catch\nKeep the three nested try/catch blocks; replace each swallow with a log line and an explicit deny result. No restructuring.\nC) Keep as described\nLeave validateAndDispatch() as the plan describes it; swallowing behavior recorded as an accepted risk.\n\nState: approved\nActual answer: A) Explicit error map (recommended) — user answer to D4.\nAccepted scope: Rewrite validateAndDispatch() as validate → decideAccess → dispatch inside one try; a single catch maps each known error class to an explicit outcome and structured log (tenant ID, request ID); unknown errors deny and re-throw; table-driven unit test per error class. Deny-by-default is the contract (also closes finding A3). R0–R2 unchanged.\nHistory: none.\n\n### R4: Shared get-or-load path for the cache-miss sequence (DRY)\nFinding: C2, P2, confidence 6/10 (medium — verify this is actually an issue; no source to quote both call sites), `PLAN.md:29` (\"Both services mutate it.\"), reviewer: Claude (plan-eng-review).\nPlan baseline: original proposal — each service implements its own read → miss → IDP → write sequence against AuthCache.\nRuntime evidence: unknown — no source.\nComparison grid:\n\n| Choice | Current | A | B | C |\n|---|---|---|---|---|\n| R4 cache-miss sequence location | duplicated in AuthBroker and SessionMint (inferred) | one `AuthCache.getOrLoad(key, loader)` that reads, calls the loader on miss, and writes through the R2 generation guard; both services call it | each service keeps its own read/miss/write code | defer: implement per-service first, revisit if duplication is confirmed in code |\n| R0–R3 (approved) | — | unchanged | unchanged | unchanged |\n\nQuestion D5:\nD5 — Should the read → miss → load → write sequence live once in AuthCache.getOrLoad(), or in each service?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md); D1–D4 fixed structure, injection, the generation guard and the error map.\nELI10: Both AuthBroker and SessionMint need the same dance: look in the cache, if it is not there ask the IDP, then store the answer. If each service writes that dance itself, the generation guard from D3 has to be remembered in two places and a future fix lands in one and not the other. Putting the dance in one method on the cache facade means the guard is applied automatically wherever a load happens.\nStakes if we pick wrong: with duplication, one service eventually bypasses the guard or diverges on key construction and a tenant-key bug appears in only one flow; with a bad abstraction, a loader signature too generic for the two real callers.\nRecommendation: A because the two callers are known now, the guard from D3 must wrap every write, and one helper is the DRY-aggressive default for this codebase (human: ~3h / CC: ~10 min).\nCompleteness: A=10/10, B=5/10, C=n/a (deferral, no remedy)\nPros / cons:\nA) One `AuthCache.getOrLoad(key, loader)` used by both services (recommended)\n  ✅ The D3 generation guard and the tenant/issuer/audience/policy-version key construction are applied in exactly one place\n  ✅ Both services shrink to \"call getOrLoad with my loader\"; tests for the miss path are written once\n  ❌ A loader callback is one more indirection to read; if the two callers turn out to need different miss semantics the helper grows a flag\nB) Each service keeps its own read/miss/write sequence\n  ✅ Each flow stays fully explicit at its own call site with no callback indirection\n  ✅ No shared helper to design before the two callers exist\n  ❌ Two copies of the miss path; the guard and key rules must be maintained twice and tested twice\nC) Defer until duplication is confirmed in code\n  ✅ Avoids abstracting on an inference; the plan text does not literally show both sequences\n  ✅ Cheap to revisit once the first service is written\n  ❌ Leaves the guard-application rule unowned during implementation; the second service may ship before the revisit\nNet: trading a small callback indirection against maintaining the security-relevant miss path in two places.\nHeader: DRY miss path\nOptions:\nA) getOrLoad in AuthCache (recommended)\nAdd `AuthCache.getOrLoad(key, loader)`: read; on miss call loader; write through the R2 generation guard. AuthBroker and SessionMint both use it for their cache-miss sequences. Tested once in AuthCache.\nB) Per-service sequences\nEach service implements its own read → miss → IDP → write against AuthCache.get/put. Guard and key rules maintained at both sites.\nC) Defer\nImplement per-service first; revisit consolidation when the duplication is confirmed in code. Approves no consolidation now.\n\nState: approved\nActual answer: A) getOrLoad in AuthCache (recommended) — user answer to D5.\nAccepted scope: Add `AuthCache.getOrLoad(key, loader)`: read; on miss call loader; write through the R2 generation guard. AuthBroker and SessionMint both use it for their cache-miss sequences; tested once in AuthCache. R0–R3 unchanged.\nHistory: none.\n\n### R5: Regression contract for legacyAuthFlow() rewrite (IRON RULE)\nFinding: T1, P1, confidence 9/10, `PLAN.md:36-37` (\"The existing `legacyAuthFlow()` will get rewritten as part of this work; no regression test for the prior behavior is planned.\") and `PLAN.md:24-25` (\"That coverage does not exercise legacyAuthFlow() or assert compatibility with its prior behavior.\"), reviewer: Claude (plan-eng-review).\nPlan baseline: original proposal — rewrite with no regression coverage.\nRuntime evidence: unknown — no source; legacyAuthFlow()'s callers and current outcomes are not in the repository.\nComparison grid:\n\n| Choice | Current | A | B | C |\n|---|---|---|---|---|\n| R5 regression coverage for legacyAuthFlow behavior | none | characterization suite captured from legacyAuthFlow() BEFORE the rewrite, then run against the new flow: valid token, expired, revoked, logged-out, suspended tenant, cross-tenant token, policy-version bump, malformed token, IDP unavailable, IDP timeout; asserts outcome class AND cache state | A plus a flag-gated shadow compare: new flow runs alongside legacy in production for a bounded window, decisions compared and mismatches logged/alerted; legacy remains authoritative until the flag flips | happy-path characterization only: valid + expired token |\n| Behavior to preserve | all legacy allow/deny outcomes and cache effects | all, byte-for-byte on outcome class | all, byte-for-byte on outcome class, verified in prod traffic | valid/expired only |\n| Intentional differences | none stated | only D4's explicit deny where legacy swallowed an error; each such case is listed and asserted as an intentional change | same as A | same as A |\n| R0–R4 (approved) | — | unchanged | unchanged | unchanged |\n\nQuestion D6:\nD6 — How do we prove the rewritten auth flow behaves exactly like legacyAuthFlow() before the old one is deleted?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md); D1–D5 fixed structure, injection, guard, error map and getOrLoad.\nELI10: The plan rewrites the function every tenant login goes through and, as written, has no test that says \"the new one answers the same as the old one.\" The way to get that safely is to write the tests against the OLD function first, so they capture what it actually does today (including its quirks), then point the same tests at the new function. For an auth path you can go one step further and run both in production for a while, letting the old one decide while logging any disagreement.\nStakes if we pick wrong: a tenant that could log in yesterday cannot today, or a token that should be rejected is accepted, and there is no test that would have caught it before deploy.\nRecommendation: B because characterization tests catch what you thought of and the shadow compare catches what you did not; on an auth path the extra flag is cheap insurance and is removed when the window closes (A: human ~1.5 days / CC ~30 min; B: human ~3 days / CC ~45 min).\nCompleteness: A=9/10, B=10/10, C=5/10\nPros / cons:\nA) Characterization suite captured from legacyAuthFlow() first, then run against the new flow\n  ✅ Locks in every listed outcome class before a line of the rewrite exists; failures point at the exact diverging case\n  ✅ Also serves as the acceptance suite for D4: every intentionally changed outcome is listed and asserted as changed, nothing changes silently\n  ❌ Only covers cases someone thought to write; real token shapes and IDP behaviors in production may differ\nB) A plus a flag-gated shadow compare in production for a bounded window (recommended)\n  ✅ Real traffic across real tenants checks the rewrite against the legacy decision; mismatches are logged with tenant and case, never enforced\n  ✅ Reversible by construction: legacy stays authoritative until the flag flips, so rollback is a config change\n  ❌ Adds a flag, a compare hook and a cleanup task; doubles IDP calls during the window unless the compare reuses the cached result\nC) Happy-path characterization only (valid and expired token)\n  ✅ Fast to write and covers the two most common outcomes users hit every day\n  ✅ Still better than the plan's zero regression coverage\n  ❌ Revocation, suspension, cross-tenant and IDP-failure paths, the ones with security consequences, remain unproven\nNet: trading a temporary flag and compare hook against discovering an auth regression from a tenant's support ticket.\nHeader: Regression\nOptions:\nA) Characterization suite\nWrite the regression suite against legacyAuthFlow() before the rewrite covering valid, expired, revoked, logged-out, suspended tenant, cross-tenant, policy-version bump, malformed token, IDP unavailable and IDP timeout; assert outcome class and cache state. The new flow must pass it; intentional D4 differences are listed and asserted explicitly.\nB) Characterization + shadow compare (recommended)\nEverything in A, plus a flag-gated shadow mode where the new flow runs alongside legacy in production for a bounded window; legacy decides, mismatches are logged and alerted; the flag flips only after a clean window; flag and legacy are removed afterwards.\nC) Happy path only\nCharacterization tests for valid and expired token only. The remaining legacy outcomes are recorded as unproven in the report.\n\nState: approved\nActual answer: A) Characterization suite — user answer to D6 (recommendation was B; user chose A, completeness 9/10).\nAccepted scope: Regression contract — write the characterization suite against legacyAuthFlow() BEFORE the rewrite covering valid, expired, revoked, logged-out, suspended tenant, cross-tenant token, policy-version bump, malformed token, IDP unavailable and IDP timeout; assert outcome class and cache state. The new flow must pass the same suite. Intentional differences: only D4's explicit deny where legacy swallowed an error; each such case is listed and asserted as an intentional change. Shadow compare NOT approved (candidate TODO). R0–R4 unchanged.\nHistory: none.\n\n### R6: Integration (E2E) depth for the new flow\nFinding: T2, P2, confidence 8/10, `PLAN.md:23-24` (\"Unit and integration coverage is planned for the new components and their success/error paths.\") — the plan names no end-to-end scenario spanning AuthBroker → decideAccess → dispatch → AuthCache → SessionMint across tenants, reviewer: Claude (plan-eng-review).\nPlan baseline: original proposal — unit and integration coverage of new components' success/error paths, scenario list unspecified.\nRuntime evidence: unknown — no source, no test files.\nComparison grid:\n\n| Choice | Current | A | B |\n|---|---|---|---|\n| R6 E2E depth | unspecified integration coverage | two-tenant E2E against a fake IDP: login → validate → decideAccess → dispatch for tenants A and B; cross-tenant token rejected; suspension of A mid-session denies A's next request and leaves B untouched; IDP outage → explicit 503 path; policy-version bump → cache miss and re-validate | component-level integration only: each new unit against the fake adapter/fake IDP, no cross-unit scenario |\n| Common work (no approval needed): proof of existing contracts PLAN.md:16-22 | — | tenant-key isolation and logout/revocation/suspension propagation through the facade | same |\n| R0–R5 (approved) | — | unchanged | unchanged |\n\nQuestion D7:\nD7 — How deep should the integration test for the new flow go: a two-tenant end-to-end scenario, or component-level only?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md); D1–D6 fixed structure, wiring, guard, error map, getOrLoad and the regression suite.\nELI10: Unit tests prove each piece works alone; the bugs in auth systems usually live in the seams, like tenant A's suspension accidentally clearing tenant B's sessions, or the cache key missing one field so two tenants share an entry. One end-to-end test that runs two tenants through the whole login-to-dispatch path with a fake identity provider catches exactly those seam bugs. It is the kind of test you want to fail in CI, not in a customer's browser.\nStakes if we pick wrong: a cross-tenant leak or a suspension that does not stick reaches production because every unit test passed in isolation.\nRecommendation: A because auth flows spanning 3+ components are the textbook E2E case and the fake IDP makes it deterministic (human: ~1 day / CC: ~20 min).\nCompleteness: A=10/10, B=7/10\nPros / cons:\nA) Two-tenant E2E against a fake IDP, including suspension mid-session, cross-tenant token, IDP outage and policy-version bump (recommended)\n  ✅ Exercises AuthBroker, decideAccess, AuthCache (with the D3 guard), SessionMint and dispatch together across two tenants\n  ✅ Failure modes that matter to real users (suspension not sticking, cross-tenant leak, IDP down) are asserted end to end\n  ❌ Needs a fake IDP fixture and takes longer per run than unit tests; must stay deterministic (no real network)\nB) Component-level integration only\n  ✅ Each unit is verified against fake collaborators quickly; no fixture for a full IDP conversation\n  ✅ Matches the plan's wording of \"unit and integration coverage\" with minimal extra scope\n  ❌ Seam bugs between units (key construction, invalidation propagation, dispatch after deny) are not exercised together\nNet: trading one fake-IDP fixture against finding tenant-isolation bugs only in production.\nHeader: E2E depth\nOptions:\nA) Two-tenant E2E (recommended)\nOne end-to-end test file against a fake IDP: tenants A and B log in, validate, decideAccess and dispatch; cross-tenant token rejected; suspending A mid-session denies A's next request and leaves B untouched; IDP outage yields the explicit 503 path; policy-version bump forces a re-validate. Plus the common-work facade contract tests.\nB) Component-level only\nIntegration tests per unit against fake adapter and fake IDP; no cross-unit scenario. Plus the common-work facade contract tests.\n\nState: approved\nActual answer: A) Two-tenant E2E (recommended) — user answer to D7.\nAccepted scope: One end-to-end test file against a fake IDP: tenants A and B log in, validate, decideAccess and dispatch; cross-tenant token rejected; suspending A mid-session denies A's next request and leaves B untouched; IDP outage yields the explicit 503 path; policy-version bump forces a re-validate. Plus the common-work facade contract tests (tenant-key isolation; logout/revocation/suspension propagation through the facade). R0–R5 unchanged.\nHistory: none.\n\n### R7: Parallelizing the 5 IDP calls (Promise.all)\nFinding: P1, P2, confidence 7/10, `PLAN.md:40-41` (\"Token validation issues 5 sequential API calls to the IDP; they could be parallelized via Promise.all trivially (calls are independent).\"), reviewer: Claude (plan-eng-review). The independence claim is unverified (no source); parallelization changes error ordering, timeout behavior and IDP concurrency, so it is a behavior change inside a plan whose goal is \"without changing its product behavior\" (`PLAN.md:8-9`).\nPlan baseline: original proposal — parallelize via Promise.all as part of this work.\nRuntime evidence: unknown — whether any of the 5 calls consumes a prior call's output (e.g. discovery → JWKS → introspection) and what the IDP's per-client concurrency limit is are not stated.\nComparison grid:\n\n| Choice | Current | A | B | C |\n|---|---|---|---|---|\n| R7 IDP call parallelization | 5 sequential calls; plan proposes Promise.all inside the refactor | separate, final commit on this branch AFTER the D6 suite is green against the new flow; preconditions: bounded probe confirms no call depends on another's output and the IDP tolerates 5 concurrent calls per validation; Promise.all fail-fast, first rejection routed through the D4 error map; before/after latency recorded | keep sequential in this refactor; parallelization deferred to a TODO with the same preconditions | Promise.all inline in the refactor commit as the plan proposes |\n| Timeout/error semantics | first failure stops the chain | first rejection rejects the whole validation (fail-fast); in-flight siblings are abandoned; timeout per call unchanged | unchanged | first rejection rejects the whole validation |\n| R0–R6 (approved) | — | unchanged | unchanged | unchanged |\n\nQuestion D8:\nD8 — When should the 5 IDP calls be parallelized: as a separate final commit after regression is green, deferred, or inline in the refactor?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md); D1–D7 fixed structure, wiring, guard, error map, getOrLoad, regression suite and E2E depth.\nELI10: Making five calls at once instead of one after another is a real speed win for every login, but it is also a behavior change: errors arrive in a different order, five requests hit the identity provider at the same instant, and if one call secretly needs another's answer it breaks. The plan's goal is \"no behavior change,\" so the clean move is to finish the reorganization, prove it matches the old flow with the regression suite, then flip to parallel in its own commit where any difference is obviously caused by that one change.\nStakes if we pick wrong: mixed into the refactor, a regression-suite failure could be either the restructure or the parallelization and you cannot tell which; deferred forever, users keep paying five round trips on every validation.\nRecommendation: A because it keeps structural and behavioral changes in separate commits (Beck) while still landing the win on this branch; the probe of independence and IDP limits is a few minutes once source is available (human: ~half day / CC: ~15 min).\nNote: options differ in kind, not coverage — no completeness score.\nPros / cons:\nA) Separate final commit after the regression suite is green, gated on the independence and rate-limit probe (recommended)\n  ✅ A regression failure after this commit has exactly one cause; rollback is one revert with the refactor intact\n  ✅ The \"calls are independent\" claim is checked against source, and IDP concurrency limits are confirmed before five simultaneous requests ship\n  ❌ One extra commit and a short probe before the latency win lands\nB) Keep sequential in this refactor; defer parallelization to a TODO\n  ✅ The branch stays a pure reorganization with zero timing or error-ordering change\n  ✅ No IDP rate-limit risk introduced by this work\n  ❌ A known 5x-round-trip latency cost on every validation stays in production with no scheduled fix\nC) Promise.all inline in the refactor commit as the plan proposes\n  ✅ Fewest commits; the win ships with the refactor\n  ✅ No separate PR or coordination step\n  ❌ Mixes a behavior change into a \"no behavior change\" refactor; regression-suite failures become ambiguous and the independence claim ships unverified\nNet: trading one extra commit and a short probe against ambiguous regression failures in the auth path.\nHeader: IDP parallel\nOptions:\nA) Separate final commit (recommended)\nLand Promise.all as its own last commit on this branch after the D6 characterization suite is green against the new flow. Preconditions: bounded probe confirms no call consumes another's output and the IDP tolerates 5 concurrent calls per validation; fail-fast semantics, first rejection routed through the D4 error map; before/after latency recorded in the PR.\nB) Defer to TODO\nKeep the 5 calls sequential in this refactor. Parallelization becomes a TODO with the same preconditions. No timing change on this branch.\nC) Inline in refactor\nApply Promise.all inside the refactor commit as the plan proposes; no independence probe required beforehand.\n\nState: approved\nActual answer: A) Separate final commit (recommended) — user answer to D8.\nAccepted scope: Land Promise.all as its own last commit on this branch after the D6 characterization suite is green against the new flow. Preconditions: bounded probe confirms no call consumes another's output and the IDP tolerates 5 concurrent calls per validation; fail-fast semantics, first rejection routed through the D4 error map; before/after latency recorded in the PR. R0–R6 unchanged.\nHistory: none.\n\n### R8: TODO candidate — flag-gated shadow compare of new flow vs legacyAuthFlow() in production\nFinding: derived from D6 (user chose A over recommended B), reviewer: Claude (plan-eng-review). Not a defect; a deferred rollout-safety measure.\nPlan baseline: not in plan (D6 approved the characterization suite only).\nRuntime evidence: n/a.\nComparison grid:\n\n| Choice | Current | A | B | C |\n|---|---|---|---|---|\n| R8 disposition of shadow-compare idea | not captured | add to TODOS.md with full context (not persisted in plan mode: repo write forbidden; content presented) | skip: not valuable enough | build it now in this branch (reopens D6's accepted scope) |\n| R0–R7 (approved) | — | unchanged | unchanged | unchanged (C would reopen R5) |\n\nQuestion D9:\nD9 — TODO: capture \"flag-gated shadow compare of the new auth flow against legacyAuthFlow() in production\" for later?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md); D6 approved the characterization suite without the production shadow compare.\nELI10: You chose to prove the rewrite with tests written against the old code. The other half of the idea, running both old and new in production for a while and logging any disagreement, was not taken. This question is only about whether to write that idea down properly so a future session can pick it up with the reasoning intact, not about doing it now.\nStakes if we pick wrong: skip it and the idea evaporates; capture it badly and someone later wonders why it exists.\nRecommendation: A because it costs one paragraph now and is the standard next step if the characterization suite ever misses a production-only token shape.\nNote: options differ in kind, not coverage — no completeness score.\nWhat: flag-gated shadow mode where the new flow runs alongside legacyAuthFlow() for a bounded window; legacy decides; mismatches logged with tenant and case; flag flips after a clean window, then flag and legacy are deleted.\nWhy: catches production-only token shapes and IDP behaviors the characterization suite did not anticipate; makes cutover reversible by config.\nPros: real-traffic proof across all tenants; rollback is a config change.\nCons: temporary flag and compare hook; doubles IDP calls during the window unless the compare reuses the cached result; cleanup task.\nContext: D6 in this review approved characterization tests (10 scenarios) as the regression contract. If the suite passes but any post-cutover incident shows a divergence, this is the next tool. Start at the composition root (D2) where both flows can be constructed side by side.\nDepends on / blocked by: the characterization suite (D6) green against the new flow; legacyAuthFlow() must still exist when shadow mode is added.\nPros / cons:\nA) Add to TODOS.md (recommended)\n  ✅ Idea and its reasoning survive with a clear starting point (composition root) and trigger\n  ✅ Zero implementation cost now; does not change any approved scope\n  ❌ TODOS.md cannot be written in plan mode; content is presented as not persisted until you leave plan mode\nB) Skip — not valuable enough\n  ✅ Keeps the TODO list focused if you are confident the suite is sufficient\n  ✅ Nothing to maintain or clean up later\n  ❌ The reasoning is lost; a future incident re-derives it from scratch\nC) Build it now in this branch\n  ✅ Maximum rollout safety for an auth cutover\n  ✅ The flag and compare hook are small once the composition root exists\n  ❌ Reopens D6's accepted scope and adds a flag and cleanup task to a branch whose goal is a reorganization\nNet: one paragraph of captured reasoning versus nothing.\nHeader: TODO shadow\nOptions:\nA) Add to TODOS.md (recommended)\nRecord the What/Why/Pros/Cons/Context/Depends block above in TODOS.md (presented as not persisted while in plan mode). No implementation now.\nB) Skip\nDo not capture; the idea is dropped from this review's outputs.\nC) Build it now\nReopen D6 and add the flag-gated shadow compare to this branch's accepted scope; a follow-up decision will re-record R5.\n\nState: approved\nActual answer: A) Add to TODOS.md (recommended) — user answer to D9.\nAccepted scope: TODO entry (What/Why/Pros/Cons/Context/Depends as above) for TODOS.md; presented as not persisted while in plan mode. No implementation; R0–R7 unchanged.\nHistory: none.\n\n### R9: TODO candidate — single-flight de-duplication in AuthCache.getOrLoad() for policy-version cache storms\nFinding: P2 (Performance), P3, confidence 8/10, `PLAN.md:16-17` (cache keyed by \"tenant ID, issuer, audience, and policy version\") — a policy-version bump invalidates every entry for that tenant at once; all concurrent requests miss and each calls the IDP (thundering herd). Existing behavior, not introduced by this plan. Reviewer: Claude (plan-eng-review).\nPlan baseline: not in plan.\nRuntime evidence: unknown — request volume per tenant and IDP rate limits not stated.\nComparison grid:\n\n| Choice | Current | A | B | C |\n|---|---|---|---|---|\n| R9 disposition of single-flight idea | not captured | add to TODOS.md with full context (not persisted in plan mode) | skip | build now: in-process single-flight map inside getOrLoad (reopens R4's accepted scope) |\n| R0–R8 (approved) | — | unchanged | unchanged | unchanged (C would reopen R4) |\n\nQuestion D10:\nD10 — TODO: capture \"single-flight de-duplication of concurrent cache misses in AuthCache.getOrLoad()\" for later?\nProject/branch/task: main — Multi-tenant Auth Refactor plan (PLAN.md); D5 approved getOrLoad as the single miss path.\nELI10: When a tenant's policy version changes, every cached token for that tenant becomes a miss at the same moment, and every in-flight request asks the identity provider separately. Single-flight means the first miss for a key does the IDP call and the others wait for that same answer. It is an existing cost, not something this refactor introduces, but D5 just created the one place where it would be a small change. This question is only about writing it down.\nStakes if we pick wrong: skip and a busy tenant's policy bump keeps producing an IDP burst nobody remembers is avoidable; capture and the fix has an obvious home.\nRecommendation: A because getOrLoad is the right home and the reasoning is cheap to keep; building now would add behavior to a reorganization branch.\nNote: options differ in kind, not coverage — no completeness score.\nWhat: per-key in-flight promise map inside AuthCache.getOrLoad(); concurrent misses for the same key share one loader call; entry cleared on settle.\nWhy: a policy-version bump or cold start for a large tenant turns N concurrent requests into N IDP calls; single-flight makes it 1.\nPros: cuts IDP load and tail latency during invalidation storms; lives in the one approved miss path.\nCons: in-process only (no cross-instance de-dup); must respect the D3 generation guard (a shared result observed before an invalidation must still be dropped); needs a concurrency test.\nContext: D5 approved `AuthCache.getOrLoad(key, loader)` as the single read → miss → load → write path. Add the in-flight map there; the generation check on write already exists (D3). Measure IDP call count during a policy bump before and after.\nDepends on / blocked by: getOrLoad landed (D5); the D8 parallelization commit (to avoid two performance changes in one measurement).\nPros / cons:\nA) Add to TODOS.md (recommended)\n  ✅ Fix has a named home (getOrLoad) and a named trigger (policy-version bump burst) for whoever picks it up\n  ✅ No change to any approved scope on this branch\n  ❌ Not persisted while in plan mode; the IDP burst remains until someone picks it up\nB) Skip — not valuable enough\n  ✅ Keeps the TODO list focused if policy bumps are rare and tenants are small\n  ✅ Nothing to maintain\n  ❌ Existing IDP burst cost stays unrecorded\nC) Build it now in this branch\n  ✅ Small once getOrLoad exists; removes a real burst cost immediately\n  ✅ Concurrency test can share fixtures with the D3 guard test\n  ❌ Adds behavior to a reorganization branch and reopens R4's accepted scope\nNet: one paragraph now versus an unrecorded burst cost.\nHeader: TODO herd\nOptions:\nA) Add to TODOS.md (recommended)\nRecord the What/Why/Pros/Cons/Context/Depends block above in TODOS.md (presented as not persisted while in plan mode). No implementation now.\nB) Skip\nDo not capture; the idea is dropped from this review's outputs.\nC) Build it now\nReopen D5 and add in-process single-flight to getOrLoad on this branch; a follow-up decision will re-record R4.\n\nState: approved\nActual answer: A) Add to TODOS.md (recommended) — user answer to D10.\nAccepted scope: TODO entry (What/Why/Pros/Cons/Context/Depends as above) for TODOS.md; presented as not persisted while in plan mode. No implementation; R0–R8 unchanged.\nHistory: none.\n\n### Approval readiness: PASS\nEvery record R0–R9 has `State: approved` with the user's actual answer (D1–D10) and an accepted-scope block; no record is pending, superseded-without-successor, or answered by a setup/prerequisite question. No remedy was implemented; the plan text above reflects only approved values.\n\n---\n\n## GSTACK REVIEW REPORT\n\n| Review | Status | Runs | Key finding |\n|---|---|---|---|\n| CEO Review | — | 0 runs | not run |\n| Outside Review | codex, disabled | 1 run | codex_reviews=disabled — skipped, no native replacement |\n| Eng Review | CLEAR | 1 run | 12 issues, 0 critical gaps (A1–A5, C1–C3, T1–T2, P1–P2; scope gate S1–S2 resolved by D1/D8) |\n| Design Review | — | 0 runs | no UI in scope |\n| DX Review | — | 0 runs | not run |\n\nOUTSIDE COVERAGE: codex disabled — this review is Claude-only; enable with `gstack-config set codex_reviews enabled` for a second opinion.\n\nVERDICT: ENG CLEARED — ready to implement. Scope reduced to 3 units (D1); 10 decisions approved (D1–D10); regression contract is the characterization suite written before the rewrite (D6, IRON RULE); parallelization isolated to a final commit (D8).\n\nNO UNRESOLVED DECISIONS\n",
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