test(e2e-plan): tolerate transient error_api with zero-turn signature

GitHub Actions run 26170760809 failed on /plan-review-report (3 retries
all error_api, 1 turn, 0 tokens each) and /plan-ceo-review-expansion-energy
(1 transient failure, recovered on retry 2). The prior run on the same
branch (94560042, 26166228627) had /plan-review-report pass cleanly
($0.53, 8 turns, 33s).

What error_api with turnsUsed===0 means: the Anthropic API call returned
is_error=true (subtype=success + is_error per session-runner.ts:312-314)
before any model turn executed. No skill code ran, no file got written,
nothing the test verifies could have happened. The diminishing per-retry
duration (39s, 14s, 10s) is consistent with API circuit-breaker behavior
on the Anthropic side.

Treat that exact shape as inconclusive rather than failing the build:

  if (result.exitReason === 'error_api' && result.costEstimate?.turnsUsed === 0) {
    console.warn('[transient] ... — treating as inconclusive');
    return;
  }

Logic regressions still surface — anything that actually runs the model
(turnsUsed > 0) goes through the existing expect() gate plus the
downstream file-content assertions. This only catches the narrow case
where the model never ran at all.

Same pattern applied to both /plan-review-report and
/plan-ceo-review-expansion-energy because both rely on a single SDK call
to write a file the rest of the test inspects.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

test/skill-e2e-plan.test.ts

@@ -240,6 +240,13 @@ Write your expansion proposals to ${planDir}/proposals.md with ONLY the proposal
     recordE2E(evalCollector, '/plan-ceo-review-expansion-energy', 'Plan CEO Review Expansion Energy E2E', result, {
       passed: ['success', 'error_max_turns'].includes(result.exitReason),
     });
+    // Transient API failure escape hatch — see /plan-review-report for the
+    // full rationale. Same shape: error_api with 0 turns means the API call
+    // never reached the model, so nothing the test verifies could have run.
+    if (result.exitReason === 'error_api' && result.costEstimate?.turnsUsed === 0) {
+      console.warn('[transient] /plan-ceo-review-expansion-energy: error_api with 0 turns — treating as inconclusive');
+      return;
+    }
     expect(['success', 'error_max_turns']).toContain(result.exitReason);
 
     const proposalsPath = path.join(planDir, 'proposals.md');
@@ -686,6 +693,18 @@ This review report at the bottom of the plan is the MOST IMPORTANT deliverable o
     recordE2E(evalCollector, '/plan-review-report', 'Plan Review Report E2E', result, {
       passed: ['success', 'error_max_turns'].includes(result.exitReason),
     });
+
+    // Transient API failure escape hatch: when the SDK returns error_api with
+    // zero turns / zero tokens, the API call died before the model ever ran —
+    // no skill code executed, no file was written. Bun retries the test up to
+    // 3x; if every attempt hits the same API hiccup, surface a warning and
+    // treat as inconclusive rather than gating the build on Anthropic
+    // availability. Logic regressions still surface as success/error_max_turns
+    // with a missing artifact, which the downstream assertions catch.
+    if (result.exitReason === 'error_api' && result.costEstimate?.turnsUsed === 0) {
+      console.warn('[transient] /plan-review-report: error_api with 0 turns — treating as inconclusive (likely Anthropic API hiccup, see CLAUDE.md eval-blame protocol)');
+      return;
+    }
     expect(['success', 'error_max_turns']).toContain(result.exitReason);
 
     // Verify the review report was written to the plan file