diff --git a/bin/gstack-slug b/bin/gstack-slug
index 924454722..fb164a69b 100755
--- a/bin/gstack-slug
+++ b/bin/gstack-slug
@@ -13,11 +13,30 @@
 #      Without this walk-up, running gstack-slug from a subdir whose only
 #      "marker" is a deploy artifact silently resolves to the subdir's basename,
 #      misfiling all session state under a phantom slug. (2026-05-25 bug fix.)
-#   2. If the resolved project root has a git remote, derive the slug from it.
+#   2. Derive the slug from the canonical git remote: the OUTERMOST ancestor
+#      that is an actual git repo (`.git` directory, or `.git` FILE for
+#      worktrees/submodules) with an `origin` remote wins. The slug is
+#      `owner-repo`, parsed EXACTLY like browse/bin/remote-slug so the two
+#      bins can never disagree on a canonical-remote repo. Marker-only
+#      ancestors that are NOT remote-bearing repos (a stray empty ~/.git,
+#      a stray package.json in $HOME) still anchor the basename FALLBACK,
+#      but they can no longer shadow a real remote. (2026-08-17 bug fix:
+#      a stray empty ~/.git made the walk-up pick $HOME as project root;
+#      $HOME has no origin, so EVERY repo under it degraded to
+#      SLUG=<username> — one shared bucket for all projects.)
 #   3. Otherwise use the basename of the resolved project root.
 #   4. If no project root was found anywhere on the chain, fall back to the
 #      basename of $(pwd) (preserves prior behavior for plain folders).
 #
+# MIGRATION NOTE (2026-08-17): sessions run BEFORE the remote-first fix above,
+# in repos below a stray marker-bearing ancestor, filed their session state
+# (decisions / timeline / ceo-plans / learnings) under the DEGRADED slug —
+# ~/.gstack/projects/<ancestor-basename>/ (e.g. `garrytan`) instead of the
+# canonical ~/.gstack/projects/<owner-repo>/. The slug cache self-heals on the
+# next invocation (see 1b), but already-written store data does NOT move.
+# Whether/how to merge those stores is tracked in TODOS.md — do not add data
+# migration code here.
+#
 # Caching is self-healing: a cache entry for the literal pwd that differs from
 # the freshly-computed slug gets opportunistically rewritten (single-shot, key-
 # local — never sweeps other entries). This lets pre-existing poisoned caches
@@ -112,6 +131,32 @@ _outermost_project_root() {
   fi
 }
 
+# 1a. Outermost REMOTE-BEARING repo root: walk the same ancestor chain and
+#     track the outermost dir that has a `.git` entry (directory for normal
+#     clones, FILE for git-worktrees/submodules — `git -C` resolves a
+#     worktree's remote through its main clone) AND whose `origin` remote
+#     resolves. This is the canonical-identity walk: a marker-only ancestor
+#     with no resolvable origin (stray empty ~/.git, stray package.json)
+#     cannot win here, so it cannot hijack remote-derived identity the way
+#     it can hijack the marker walk above. Nested-repo semantics preserved:
+#     an inner repo under an outer canonical-remote repo still resolves to
+#     the OUTER repo's remote (outermost wins), same as before.
+#     Note: git spawns only at `.git`-bearing ancestors — typically one.
+_outermost_remote_repo() {
+  local dir="$1"
+  local outermost="" parent="" depth=0
+  while [[ -n "$dir" && "$dir" != "/" && $depth -lt 64 ]]; do
+    if [[ -e "$dir/.git" ]] && git -C "$dir" remote get-url origin >/dev/null 2>&1; then
+      outermost="$dir"
+    fi
+    parent=$(dirname "$dir")
+    [[ "$parent" == "$dir" ]] && break # dirname fixed point (C:/, ., //srv)
+    dir="$parent"
+    depth=$((depth + 1))
+  done
+  printf '%s' "$outermost"
+}
+
 # Only compute the project root if we don't already have a slug (env override
 # took precedence). The walk is cheap (~10 stats on the deepest realistic cwd).
 PROJECT_ROOT=""
@@ -119,34 +164,65 @@ if [[ -z "$SLUG" ]]; then
   PROJECT_ROOT=$(_outermost_project_root "$PROJECT_DIR")
 fi
 
+# Lazy, memoized remote discovery. Needed on exactly two paths: fresh
+# resolution (no usable cache) and the degraded-ancestor heal check below.
+# Gating it keeps ordinary cache hits git-spawn-free.
+REMOTE_ROOT=""
+REMOTE_URL=""
+_REMOTE_RESOLVED=0
+_resolve_remote() {
+  if [[ "$_REMOTE_RESOLVED" -eq 1 ]]; then return 0; fi
+  _REMOTE_RESOLVED=1
+  REMOTE_ROOT=$(_outermost_remote_repo "$PROJECT_DIR")
+  if [[ -n "$REMOTE_ROOT" ]]; then
+    REMOTE_URL=$(git -C "$REMOTE_ROOT" remote get-url origin 2>/dev/null) || REMOTE_URL=""
+  fi
+  return 0
+}
+
 # 1b. Cached identity is STICKY (#2212): a project that used gstack before it
 #     adopted a git remote keeps its pre-origin slug — recomputing from the
 #     remote here would rename the project mid-life and orphan everything
-#     under ~/.gstack/projects/<slug>/. The ONE exception is the provable
-#     old-bug shape (#1125): the pre-walk-up resolver cached basename(pwd)
-#     for a SUBDIRECTORY of the real project — if the cached value equals this
-#     pwd's basename while the walk-up says pwd is NOT the project root, the
-#     cache came from that bug, not from legitimate identity; fall through and
-#     recompute so it heals.
+#     under ~/.gstack/projects/<slug>/. TWO provable bug shapes are exempt
+#     and fall through to recompute (self-heal):
+#     - Old-bug shape (#1125): the pre-walk-up resolver cached basename(pwd)
+#       for a SUBDIRECTORY of the real project — cached == pwd basename while
+#       the walk-up says pwd is NOT the project root.
+#     - Degraded-ancestor shape (2026-08-17): the pre-remote-first resolver
+#       cached basename(PROJECT_ROOT) for a marker-only ancestor (stray
+#       ~/.git) that is NOT the remote-bearing repo — cached == the marker
+#       root's basename while a remote-bearing repo BELOW it exists. Legit
+#       #2212 stickiness is safe: there the repo that adopted the remote IS
+#       the marker root (REMOTE_ROOT == PROJECT_ROOT), so the heal never fires.
 if [[ -z "$SLUG" && -f "$CACHE_FILE" ]]; then
   _CACHED=$(cat "$CACHE_FILE" 2>/dev/null | tr -cd 'a-zA-Z0-9._-')
   if [[ -n "$_CACHED" ]]; then
     _PWD_BASE=$(basename "$PROJECT_DIR" | tr -cd 'a-zA-Z0-9._-')
+    _ROOT_BASE=""
+    if [[ -n "$PROJECT_ROOT" ]]; then
+      _ROOT_BASE=$(basename "$PROJECT_ROOT" | tr -cd 'a-zA-Z0-9._-')
+    fi
     if [[ "$_CACHED" == "$_PWD_BASE" && -n "$PROJECT_ROOT" && "$PROJECT_ROOT" != "$PROJECT_DIR" ]]; then
       : # old-bug shape — recompute below and self-heal the cache
+    elif [[ -n "$PROJECT_ROOT" && "$_CACHED" == "$_ROOT_BASE" ]] \
+      && { _resolve_remote; [[ -n "$REMOTE_URL" && "$REMOTE_ROOT" != "$PROJECT_ROOT" ]]; }; then
+      : # degraded-ancestor shape — recompute below and self-heal the cache
     else
       SLUG="$_CACHED"
     fi
   fi
 fi
 
-# 2. If we found a project root and it has a git remote, derive slug from the
-#    remote URL (existing logic — kept verbatim, just rooted at PROJECT_ROOT
-#    instead of $PWD so a subdir without its own remote inherits the parent's).
-if [[ -z "$SLUG" && -n "$PROJECT_ROOT" ]]; then
-  REMOTE_URL=$(git -C "$PROJECT_ROOT" remote get-url origin 2>/dev/null) || REMOTE_URL=""
+# 2. Canonical remote-derived slug. Sourced from the outermost remote-bearing
+#    repo (see 1a) — NOT from PROJECT_ROOT, which may be a marker-only
+#    ancestor with no remote. Parse kept byte-identical to
+#    browse/bin/remote-slug (strip trailing .git, then owner/repo → owner-repo)
+#    so the two bins agree on every canonical-remote repo, worktrees included.
+#    Parity pinned by test/gstack-slug-parity.test.ts.
+if [[ -z "$SLUG" ]]; then
+  _resolve_remote
   if [[ -n "$REMOTE_URL" ]]; then
-    RAW_SLUG=$(printf '%s' "$REMOTE_URL" | sed 's|.*[:/]\([^/]*/[^/]*\)\.git$|\1|;s|.*[:/]\([^/]*/[^/]*\)$|\1|' | tr '/' '-')
+    RAW_SLUG=$(printf '%s' "${REMOTE_URL%.git}" | sed -E 's#.*[:/]([^/]+)/([^/]+)$#\1-\2#')
     SLUG=$(printf '%s' "$RAW_SLUG" | tr -cd 'a-zA-Z0-9._-')
   fi
 fi
diff --git a/test/gstack-slug-parity.test.ts b/test/gstack-slug-parity.test.ts
new file mode 100644
index 000000000..5e1ce5d36
--- /dev/null
+++ b/test/gstack-slug-parity.test.ts
@@ -0,0 +1,236 @@
+/**
+ * bin/gstack-slug ↔ browse/bin/remote-slug parity.
+ *
+ * The bug this pins (2026-08-17, observed live in a Conductor worktree of
+ * garrytan/gstack): a stray marker-bearing ancestor above the repo — an empty
+ * `~/.git` directory that is not even a valid git repo — captured
+ * gstack-slug's "outermost strong marker" walk-up as the project root. That
+ * ancestor has no `origin` remote, so the resolver silently degraded to
+ * `basename($HOME)` and emitted `SLUG=garrytan`, while remote-slug (which
+ * asks git for the containing repo's remote) correctly said
+ * `garrytan-gstack`. Every store keyed on the slug (decisions, timeline,
+ * ceo-plans, learnings) filed into ~/.gstack/projects/garrytan/ — one bucket
+ * shared by every repo under $HOME.
+ *
+ * The fix makes the canonical remote authoritative: gstack-slug now walks the
+ * ancestor chain for the OUTERMOST dir with a `.git` entry (dir for normal
+ * clones, FILE for git-worktrees) whose `origin` remote resolves, and derives
+ * `owner-repo` with the exact same parse remote-slug uses. Marker-only
+ * ancestors that are not remote-bearing repos can still anchor the basename
+ * FALLBACK, but they can no longer shadow a real remote.
+ *
+ * Contracts pinned here:
+ *  - Parity: for any repo (plain clone or git-worktree) whose slug derivation
+ *    reaches a canonical remote, gstack-slug's SLUG equals remote-slug's
+ *    output — including under a stray-marker home.
+ *  - Walk-up preserved: a nested inner repo under an outer canonical-remote
+ *    repo resolves to the OUTER repo's owner-repo (outermost wins), matching
+ *    remote-slug run at the outer root.
+ *  - Fallback preserved: a no-remote repo still resolves to its basename.
+ *  - Cache self-heal: a pre-fix degraded cache entry (== the bogus marker
+ *    root's basename) is rewritten to the canonical slug; legit #2212 sticky
+ *    identity (repo that adopted a remote after first use) is NOT healed.
+ *
+ * Test pattern mirrors test/gstack-slug-cwd-walk-up.test.ts: per-test
+ * tmpHome, spawnSync against the real bash scripts, fixtures on disk.
+ */
+import { describe, test, expect, beforeEach, afterEach } from 'bun:test';
+import { spawnSync, type SpawnSyncReturns } from 'child_process';
+import * as fs from 'fs';
+import * as path from 'path';
+import * as os from 'os';
+
+const ROOT = path.resolve(import.meta.dir, '..');
+const SLUG_SCRIPT = path.join(ROOT, 'bin', 'gstack-slug');
+const REMOTE_SLUG_SCRIPT = path.join(ROOT, 'browse', 'bin', 'remote-slug');
+
+function baseEnv(tmpHome: string): Record<string, string | undefined> {
+  // Drop any ambient override: a sibling test leaking GSTACK_PROJECT_SLUG in
+  // a shared-process shard would flip runs into override mode.
+  const { GSTACK_PROJECT_SLUG: _drop, ...ambient } = process.env;
+  return { ...ambient, HOME: tmpHome, GSTACK_HOME: path.join(tmpHome, '.gstack') };
+}
+
+function runSlug(cwd: string, tmpHome: string): SpawnSyncReturns<string> {
+  return spawnSync('bash', [SLUG_SCRIPT], {
+    cwd,
+    env: baseEnv(tmpHome),
+    encoding: 'utf8',
+    timeout: 10_000,
+  });
+}
+
+function runRemoteSlug(cwd: string, tmpHome: string): SpawnSyncReturns<string> {
+  return spawnSync('bash', [REMOTE_SLUG_SCRIPT], {
+    cwd,
+    env: baseEnv(tmpHome),
+    encoding: 'utf8',
+    timeout: 10_000,
+  });
+}
+
+function slugOf(r: SpawnSyncReturns<string>): string {
+  const m = r.stdout.match(/^SLUG=([^\n]*)$/m);
+  return m ? m[1]! : '';
+}
+
+function git(args: string[], opts: { cwd?: string } = {}): void {
+  const r = spawnSync('git', args, { encoding: 'utf8', timeout: 10_000, ...opts });
+  if (r.status !== 0) {
+    throw new Error(`git ${args.join(' ')} failed: ${r.stderr}`);
+  }
+}
+
+/** git init -b main + optional origin remote. Returns the repo path. */
+function makeRepo(dir: string, originUrl?: string): string {
+  fs.mkdirSync(dir, { recursive: true });
+  git(['init', '-q', '-b', 'main', dir]);
+  if (originUrl) git(['-C', dir, 'remote', 'add', 'origin', originUrl]);
+  return dir;
+}
+
+function encodedCacheKey(absPath: string): string {
+  return absPath.replace(/\//g, '_');
+}
+
+/** Assert both scripts succeed in `cwd` and emit the same slug. */
+function expectParity(cwd: string, tmpHome: string, expected: string): void {
+  const gstack = runSlug(cwd, tmpHome);
+  const remote = runRemoteSlug(cwd, tmpHome);
+  expect(gstack.status).toBe(0);
+  expect(remote.status).toBe(0);
+  const remoteOut = remote.stdout.trim();
+  expect(slugOf(gstack)).toBe(expected);
+  expect(remoteOut).toBe(expected);
+  expect(slugOf(gstack)).toBe(remoteOut);
+}
+
+describe('gstack-slug ↔ remote-slug parity', () => {
+  let tmpHome: string;
+  let fixtures: string;
+
+  beforeEach(() => {
+    // realpathSync: macOS tmpdir is a symlink (/var -> /private/var); the
+    // scripts key their cache and walk on the resolved cwd.
+    tmpHome = fs.realpathSync(fs.mkdtempSync(path.join(os.tmpdir(), 'slug-parity-home-')));
+    fixtures = fs.realpathSync(fs.mkdtempSync(path.join(os.tmpdir(), 'slug-parity-fix-')));
+  });
+
+  afterEach(() => {
+    try { fs.rmSync(tmpHome, { recursive: true, force: true }); } catch {}
+    try { fs.rmSync(fixtures, { recursive: true, force: true }); } catch {}
+  });
+
+  test('plain clone, https remote WITH .git suffix — identical owner-repo slug', () => {
+    const repo = makeRepo(path.join(fixtures, 'proj'), 'https://github.com/acme/widgets.git');
+    expectParity(repo, tmpHome, 'acme-widgets');
+  });
+
+  test('plain clone, https remote WITHOUT .git suffix (live-bug URL shape) — identical slug', () => {
+    const repo = makeRepo(path.join(fixtures, 'proj'), 'https://github.com/garrytan/gstack');
+    expectParity(repo, tmpHome, 'garrytan-gstack');
+  });
+
+  test('plain clone, scp-like ssh remote — identical owner-repo slug', () => {
+    const repo = makeRepo(path.join(fixtures, 'proj'), 'git@github.com:acme/widgets.git');
+    expectParity(repo, tmpHome, 'acme-widgets');
+  });
+
+  test('git-worktree of a clone (.git FILE, the Conductor shape) — identical slug', () => {
+    const main = makeRepo(path.join(fixtures, 'main-clone'), 'https://github.com/garrytan/gstack');
+    git(['-C', main, '-c', 'user.email=t@t', '-c', 'user.name=t', 'commit', '-q', '--allow-empty', '-m', 'init']);
+    const wt = path.join(fixtures, 'wt');
+    git(['-C', main, 'worktree', 'add', '-q', wt, '-b', 'feature-branch']);
+    // Sanity: worktree roots carry a .git FILE, not a directory.
+    expect(fs.statSync(path.join(wt, '.git')).isFile()).toBe(true);
+    expectParity(wt, tmpHome, 'garrytan-gstack');
+  });
+
+  test('LIVE BUG SHAPE: stray empty .git on an ancestor "home" no longer degrades the slug', () => {
+    // The exact 2026-08-17 reproduction: an ancestor dir with an empty .git
+    // (not a valid repo, no origin) above a canonical-remote worktree.
+    const strayHome = path.join(fixtures, 'strayhome');
+    fs.mkdirSync(path.join(strayHome, '.git'), { recursive: true }); // empty — invalid repo
+    const main = makeRepo(
+      path.join(strayHome, 'conductor', 'workspaces', 'gstack', 'main-clone'),
+      'https://github.com/garrytan/gstack',
+    );
+    git(['-C', main, '-c', 'user.email=t@t', '-c', 'user.name=t', 'commit', '-q', '--allow-empty', '-m', 'init']);
+    const wt = path.join(strayHome, 'conductor', 'workspaces', 'gstack', 'beirut-v4');
+    git(['-C', main, 'worktree', 'add', '-q', wt, '-b', 'gstack-fix-wave']);
+
+    // Both the plain clone and the worktree must resolve to owner-repo — the
+    // pre-fix resolver emitted `strayhome` (the marker root's basename) here.
+    expectParity(main, tmpHome, 'garrytan-gstack');
+    expectParity(wt, tmpHome, 'garrytan-gstack');
+    expect(slugOf(runSlug(wt, tmpHome))).not.toBe('strayhome');
+  });
+
+  test('walk-up preserved: nested inner repo (no remote) resolves to the OUTER repo slug', () => {
+    const outer = makeRepo(path.join(fixtures, 'outer'), 'git@github.com:acme/outer.git');
+    const inner = makeRepo(path.join(outer, 'vendor', 'inner'));
+
+    const gstack = runSlug(inner, tmpHome);
+    expect(gstack.status).toBe(0);
+    // Outermost remote-bearing repo wins — same answer as remote-slug asked
+    // at the outer root. (remote-slug asked from INSIDE the inner repo can't
+    // see past the inner .git — its remote derivation does not succeed there,
+    // so the parity clause doesn't apply; the walk-up contract does.)
+    expect(slugOf(gstack)).toBe('acme-outer');
+    expect(runRemoteSlug(outer, tmpHome).stdout.trim()).toBe('acme-outer');
+  });
+
+  test('walk-up preserved: nested inner repo WITH its own remote still resolves to the OUTER repo slug', () => {
+    const outer = makeRepo(path.join(fixtures, 'outer'), 'git@github.com:acme/outer.git');
+    const inner = makeRepo(path.join(outer, 'vendor', 'inner'), 'git@github.com:acme/inner.git');
+
+    const gstack = runSlug(inner, tmpHome);
+    expect(gstack.status).toBe(0);
+    // Outermost wins — unchanged from the pre-fix walk-up semantics.
+    expect(slugOf(gstack)).toBe('acme-outer');
+  });
+
+  test('fallback unchanged: no-remote repo resolves to its basename (and remote-slug agrees)', () => {
+    const repo = makeRepo(path.join(fixtures, 'lonely'));
+    const gstack = runSlug(repo, tmpHome);
+    expect(gstack.status).toBe(0);
+    expect(slugOf(gstack)).toBe('lonely');
+    // remote-slug's own no-remote fallback is basename(toplevel) — parity
+    // holds incidentally on this shape too.
+    expect(runRemoteSlug(repo, tmpHome).stdout.trim()).toBe('lonely');
+  });
+
+  test('cache self-heal: a pre-fix degraded cache entry is rewritten to the canonical slug', () => {
+    const strayHome = path.join(fixtures, 'strayhome');
+    fs.mkdirSync(path.join(strayHome, '.git'), { recursive: true });
+    const repo = makeRepo(path.join(strayHome, 'git', 'proj'), 'https://github.com/garrytan/gstack');
+
+    // Pre-seed the cache with the pre-fix degraded value: the bogus marker
+    // root's basename (what the old resolver computed and cached).
+    const cacheDir = path.join(tmpHome, '.gstack', 'slug-cache');
+    fs.mkdirSync(cacheDir, { recursive: true });
+    const cacheFile = path.join(cacheDir, encodedCacheKey(repo));
+    fs.writeFileSync(cacheFile, 'strayhome');
+
+    const gstack = runSlug(repo, tmpHome);
+    expect(gstack.status).toBe(0);
+    expect(slugOf(gstack)).toBe('garrytan-gstack');
+    // The cache file itself must have been overwritten (self-healing).
+    expect(fs.readFileSync(cacheFile, 'utf8').trim()).toBe('garrytan-gstack');
+  });
+
+  test('sticky identity preserved (#2212): repo that adopted a remote after first use is NOT healed', () => {
+    // Legit sticky shape: the repo itself is the marker root (REMOTE_ROOT ==
+    // PROJECT_ROOT) and its cached identity is its pre-origin basename slug.
+    const repo = makeRepo(path.join(fixtures, 'stickyproj'), 'https://github.com/x/y.git');
+    const cacheDir = path.join(tmpHome, '.gstack', 'slug-cache');
+    fs.mkdirSync(cacheDir, { recursive: true });
+    const cacheFile = path.join(cacheDir, encodedCacheKey(repo));
+    fs.writeFileSync(cacheFile, 'stickyproj');
+
+    const gstack = runSlug(repo, tmpHome);
+    expect(gstack.status).toBe(0);
+    expect(slugOf(gstack)).toBe('stickyproj');
+    expect(fs.readFileSync(cacheFile, 'utf8').trim()).toBe('stickyproj');
+  });
+});