diff --git a/docs-internal/FILE-SYSTEM-MAP.md b/docs-internal/FILE-SYSTEM-MAP.md
index dd67d333f..07e253cad 100644
--- a/docs-internal/FILE-SYSTEM-MAP.md
+++ b/docs-internal/FILE-SYSTEM-MAP.md
@@ -467,10 +467,9 @@
 | gsd/index.ts | GSD Workflow | Main GSD extension bootstrap and registration |
 | gsd/auto.ts | Auto Engine | Automatic workflow execution and loop management |
 | gsd/auto-dashboard.ts | Auto Engine, Web Mode | Real-time dashboard for auto-run progress |
-| gsd/auto-worktree.ts | Auto Engine, Worktree | Automatic worktree creation and branch management |
+| gsd/auto-worktree.ts | Auto Engine, Worktree | Worktree lifecycle, state sync, resource staleness, stale escape |
 | gsd/auto-recovery.ts | Auto Engine | Recovery for crashed/stalled workflows |
 | gsd/auto-start.ts | Auto Engine | Initialization sequence for automatic execution |
-| gsd/auto-worktree-sync.ts | Auto Engine, Worktree | State sync between worktrees and main |
 | gsd/auto-model-selection.ts | Auto Engine, Model System | Intelligent LLM model routing |
 | gsd/auto-direct-dispatch.ts | Auto Engine | Direct command dispatching without planning |
 | gsd/auto-dispatch.ts | Auto Engine | Task queueing and priority-based dispatch |
diff --git a/src/resources/extensions/gsd/auto-post-unit.ts b/src/resources/extensions/gsd/auto-post-unit.ts
index 1aa4471ad..77fdf1740 100644
--- a/src/resources/extensions/gsd/auto-post-unit.ts
+++ b/src/resources/extensions/gsd/auto-post-unit.ts
@@ -33,7 +33,7 @@ import {
   resolveExpectedArtifactPath,
 } from "./auto-recovery.js";
 import { regenerateIfMissing } from "./workflow-projections.js";
-import { syncStateToProjectRoot } from "./auto-worktree-sync.js";
+import { syncStateToProjectRoot } from "./auto-worktree.js";
 import { isDbAvailable, getTask, getSlice, getMilestone, updateTaskStatus, _getAdapter } from "./gsd-db.js";
 import { renderPlanCheckboxes } from "./markdown-renderer.js";
 import { consumeSignal } from "./session-status-io.js";
diff --git a/src/resources/extensions/gsd/auto-start.ts b/src/resources/extensions/gsd/auto-start.ts
index e47dc5069..7c0612bc2 100644
--- a/src/resources/extensions/gsd/auto-start.ts
+++ b/src/resources/extensions/gsd/auto-start.ts
@@ -52,7 +52,7 @@ import {
   setActiveMilestoneId,
 } from "./worktree.js";
 import { getAutoWorktreePath, isInAutoWorktree } from "./auto-worktree.js";
-import { readResourceVersion } from "./auto-worktree-sync.js";
+import { readResourceVersion, cleanStaleRuntimeUnits } from "./auto-worktree.js";
 import { initMetrics } from "./metrics.js";
 import { initRoutingHistory } from "./routing-history.js";
 import { restoreHookState, resetHookState } from "./post-unit-hooks.js";
@@ -258,31 +258,10 @@ export async function bootstrapAutoSession(
     invalidateAllCaches();
 
     // Clean stale runtime unit files for completed milestones (#887)
-    try {
-      const runtimeUnitsDir = join(gsdRoot(base), "runtime", "units");
-      if (existsSync(runtimeUnitsDir)) {
-        for (const file of readdirSync(runtimeUnitsDir)) {
-          if (!file.endsWith(".json")) continue;
-          const midMatch = file.match(/(M\d+(?:-[a-z0-9]{6})?)/);
-          if (!midMatch) continue;
-          const mid = midMatch[1];
-          if (resolveMilestoneFile(base, mid, "SUMMARY")) {
-            try {
-              unlinkSync(join(runtimeUnitsDir, file));
-            } catch (e) {
-              debugLog("stale-unit-cleanup-failed", {
-                file,
-                error: e instanceof Error ? e.message : String(e),
-              });
-            }
-          }
-        }
-      }
-    } catch (e) {
-      debugLog("stale-unit-dir-cleanup-failed", {
-        error: e instanceof Error ? e.message : String(e),
-      });
-    }
+    cleanStaleRuntimeUnits(
+      gsdRoot(base),
+      (mid) => !!resolveMilestoneFile(base, mid, "SUMMARY"),
+    );
 
     let state = await deriveState(base);
 
diff --git a/src/resources/extensions/gsd/auto-worktree-sync.ts b/src/resources/extensions/gsd/auto-worktree-sync.ts
deleted file mode 100644
index 395bb0934..000000000
--- a/src/resources/extensions/gsd/auto-worktree-sync.ts
+++ /dev/null
@@ -1,247 +0,0 @@
-/**
- * Worktree ↔ project root state synchronization for auto-mode.
- *
- * When auto-mode runs inside a worktree, dispatch-critical state files
- * (.gsd/ metadata) diverge between the worktree (where work happens)
- * and the project root (where startAutoMode reads initial state on restart).
- * Without syncing, restarting auto-mode reads stale state from the project
- * root and re-dispatches already-completed units.
- *
- * Also contains resource staleness detection and stale worktree escape.
- */
-
-import {
-  existsSync,
-  mkdirSync,
-  readFileSync,
-  cpSync,
-  unlinkSync,
-  readdirSync,
-} from "node:fs";
-import { join, sep as pathSep } from "node:path";
-import { homedir } from "node:os";
-import { safeCopy, safeCopyRecursive } from "./safe-fs.js";
-
-const gsdHome = process.env.GSD_HOME || join(homedir(), ".gsd");
-
-// ─── Project Root → Worktree Sync ─────────────────────────────────────────
-
-/**
- * Sync milestone artifacts from project root INTO worktree before deriveState.
- * Covers the case where the LLM wrote artifacts to the main repo filesystem
- * (e.g. via absolute paths) but the worktree has stale data. Also deletes
- * gsd.db in the worktree so it rebuilds from fresh disk state (#853).
- * Non-fatal — sync failure should never block dispatch.
- */
-export function syncProjectRootToWorktree(
-  projectRoot: string,
-  worktreePath: string,
-  milestoneId: string | null,
-): void {
-  if (!worktreePath || !projectRoot || worktreePath === projectRoot) return;
-  if (!milestoneId) return;
-
-  const prGsd = join(projectRoot, ".gsd");
-  const wtGsd = join(worktreePath, ".gsd");
-
-  // Copy milestone directory from project root to worktree — additive only.
-  // force:false prevents cpSync from overwriting existing worktree files.
-  // Without this, worktree-authoritative files (e.g. VALIDATION.md written
-  // by validate-milestone) get clobbered by stale project root copies,
-  // causing an infinite re-validation loop (#1886).
-  safeCopyRecursive(
-    join(prGsd, "milestones", milestoneId),
-    join(wtGsd, "milestones", milestoneId),
-    { force: false },
-  );
-
-  // Forward-sync completed-units.json from project root to worktree.
-  // Project root is authoritative for completion state after crash recovery;
-  // without this, the worktree re-dispatches already-completed units (#1886).
-  safeCopy(
-    join(prGsd, "completed-units.json"),
-    join(wtGsd, "completed-units.json"),
-    { force: true },
-  );
-
-  // Delete worktree gsd.db so it rebuilds from the freshly synced files.
-  // Stale DB rows are the root cause of the infinite skip loop (#853).
-  try {
-    const wtDb = join(wtGsd, "gsd.db");
-    if (existsSync(wtDb)) {
-      unlinkSync(wtDb);
-    }
-  } catch {
-    /* non-fatal */
-  }
-}
-
-// ─── Worktree → Project Root Sync ─────────────────────────────────────────
-
-/**
- * Sync dispatch-critical .gsd/ state files from worktree to project root.
- * Only runs when inside an auto-worktree (worktreePath differs from projectRoot).
- * Copies: STATE.md + active milestone directory (roadmap, slice plans, task summaries).
- * Non-fatal — sync failure should never block dispatch.
- */
-export function syncStateToProjectRoot(
-  worktreePath: string,
-  projectRoot: string,
-  milestoneId: string | null,
-): void {
-  if (!worktreePath || !projectRoot || worktreePath === projectRoot) return;
-  if (!milestoneId) return;
-
-  const wtGsd = join(worktreePath, ".gsd");
-  const prGsd = join(projectRoot, ".gsd");
-
-  // 1. STATE.md — the quick-glance status used by initial deriveState()
-  safeCopy(join(wtGsd, "STATE.md"), join(prGsd, "STATE.md"), { force: true });
-
-  // 2. Milestone directory — ROADMAP, slice PLANs, task summaries
-  // Copy the entire milestone .gsd subtree so deriveState reads current checkboxes
-  safeCopyRecursive(
-    join(wtGsd, "milestones", milestoneId),
-    join(prGsd, "milestones", milestoneId),
-    { force: true },
-  );
-
-  // 3. metrics.json — session cost/token tracking (#2313).
-  // Without this, metrics accumulated in the worktree are invisible from the
-  // project root and never appear in the dashboard or skill-health reports.
-  safeCopy(join(wtGsd, "metrics.json"), join(prGsd, "metrics.json"), { force: true });
-
-  // 4. Runtime records — unit dispatch state used by selfHealRuntimeRecords().
-  // Without this, a crash during a unit leaves the runtime record only in the
-  // worktree. If the next session resolves basePath before worktree re-entry,
-  // selfHeal can't find or clear the stale record (#769).
-  safeCopyRecursive(
-    join(wtGsd, "runtime", "units"),
-    join(prGsd, "runtime", "units"),
-    { force: true },
-  );
-}
-
-// ─── Resource Staleness ───────────────────────────────────────────────────
-
-/**
- * Read the resource version (semver) from the managed-resources manifest.
- * Uses gsdVersion instead of syncedAt so that launching a second session
- * doesn't falsely trigger staleness (#804).
- */
-export function readResourceVersion(): string | null {
-  const agentDir =
-    process.env.GSD_CODING_AGENT_DIR || join(gsdHome, "agent");
-  const manifestPath = join(agentDir, "managed-resources.json");
-  try {
-    const manifest = JSON.parse(readFileSync(manifestPath, "utf-8"));
-    return typeof manifest?.gsdVersion === "string"
-      ? manifest.gsdVersion
-      : null;
-  } catch {
-    return null;
-  }
-}
-
-/**
- * Check if managed resources have been updated since session start.
- * Returns a warning message if stale, null otherwise.
- */
-export function checkResourcesStale(
-  versionOnStart: string | null,
-): string | null {
-  if (versionOnStart === null) return null;
-  const current = readResourceVersion();
-  if (current === null) return null;
-  if (current !== versionOnStart) {
-    return "GSD resources were updated since this session started. Restart gsd to load the new code.";
-  }
-  return null;
-}
-
-// ─── Stale Worktree Escape ────────────────────────────────────────────────
-
-/**
- * Detect and escape a stale worktree cwd (#608).
- *
- * After milestone completion + merge, the worktree directory is removed but
- * the process cwd may still point inside `.gsd/worktrees/<MID>/`.
- * When a new session starts, `process.cwd()` is passed as `base` to startAuto
- * and all subsequent writes land in the wrong directory. This function detects
- * that scenario and chdir back to the project root.
- *
- * Returns the corrected base path.
- */
-export function escapeStaleWorktree(base: string): string {
-  // Direct layout: /.gsd/worktrees/
-  const directMarker = `${pathSep}.gsd${pathSep}worktrees${pathSep}`;
-  let idx = base.indexOf(directMarker);
-  if (idx === -1) {
-    // Symlink-resolved layout: /.gsd/projects/<hash>/worktrees/
-    const symlinkRe = new RegExp(
-      `\\${pathSep}\\.gsd\\${pathSep}projects\\${pathSep}[a-f0-9]+\\${pathSep}worktrees\\${pathSep}`,
-    );
-    const match = base.match(symlinkRe);
-    if (!match || match.index === undefined) return base;
-    idx = match.index;
-  }
-
-  // base is inside .gsd/worktrees/<something> — extract the project root
-  const projectRoot = base.slice(0, idx);
-
-  // Guard: If the candidate project root's .gsd IS the user-level ~/.gsd,
-  // the string-slice heuristic matched the wrong /.gsd/ boundary. This happens
-  // when .gsd is a symlink into ~/.gsd/projects/<hash> and process.cwd()
-  // resolved through the symlink. Returning ~ would be catastrophic (#1676).
-  const candidateGsd = join(projectRoot, ".gsd").replaceAll("\\", "/");
-  const gsdHomePath = gsdHome.replaceAll("\\", "/");
-  if (candidateGsd === gsdHomePath || candidateGsd.startsWith(gsdHomePath + "/")) {
-    // Don't chdir to home — return base unchanged.
-    // resolveProjectRoot() in worktree.ts has the full git-file-based recovery
-    // and will be called by the caller (startAuto → projectRoot()).
-    return base;
-  }
-
-  try {
-    process.chdir(projectRoot);
-  } catch {
-    // If chdir fails, return the original — caller will handle errors downstream
-    return base;
-  }
-  return projectRoot;
-}
-
-/**
- * Clean stale runtime unit files for completed milestones.
- *
- * After restart, stale runtime/units/*.json from prior milestones can
- * cause deriveState to resume the wrong milestone (#887). Removes files
- * for milestones that have a SUMMARY (fully complete).
- */
-export function cleanStaleRuntimeUnits(
-  gsdRootPath: string,
-  hasMilestoneSummary: (mid: string) => boolean,
-): number {
-  const runtimeUnitsDir = join(gsdRootPath, "runtime", "units");
-  if (!existsSync(runtimeUnitsDir)) return 0;
-
-  let cleaned = 0;
-  try {
-    for (const file of readdirSync(runtimeUnitsDir)) {
-      if (!file.endsWith(".json")) continue;
-      const midMatch = file.match(/(M\d+(?:-[a-z0-9]{6})?)/);
-      if (!midMatch) continue;
-      if (hasMilestoneSummary(midMatch[1])) {
-        try {
-          unlinkSync(join(runtimeUnitsDir, file));
-          cleaned++;
-        } catch {
-          /* non-fatal */
-        }
-      }
-    }
-  } catch {
-    /* non-fatal */
-  }
-  return cleaned;
-}
diff --git a/src/resources/extensions/gsd/auto-worktree.ts b/src/resources/extensions/gsd/auto-worktree.ts
index e91c67009..7c1e59616 100644
--- a/src/resources/extensions/gsd/auto-worktree.ts
+++ b/src/resources/extensions/gsd/auto-worktree.ts
@@ -17,7 +17,8 @@ import {
   unlinkSync,
   lstatSync as lstatSyncFn,
 } from "node:fs";
-import { isAbsolute, join } from "node:path";
+import { isAbsolute, join, sep as pathSep } from "node:path";
+import { homedir } from "node:os";
 import { GSDError, GSD_IO_ERROR, GSD_GIT_ERROR } from "./errors.js";
 import {
   reconcileWorktreeDb,
@@ -63,6 +64,38 @@ import {
   nativeIsAncestor,
 } from "./native-git-bridge.js";
 
+const gsdHome = process.env.GSD_HOME || join(homedir(), ".gsd");
+
+// ─── Shared Constants & Helpers ─────────────────────────────────────────────
+
+/**
+ * Root-level .gsd/ state files synced between worktree and project root.
+ * Single source of truth — used by syncGsdStateToWorktree, syncWorktreeStateBack,
+ * and the dispatch-level sync functions.
+ */
+const ROOT_STATE_FILES = [
+  "DECISIONS.md",
+  "REQUIREMENTS.md",
+  "PROJECT.md",
+  "KNOWLEDGE.md",
+  "OVERRIDES.md",
+  "QUEUE.md",
+  "completed-units.json",
+  "metrics.json",
+] as const;
+
+/**
+ * Check if two filesystem paths resolve to the same real location.
+ * Returns false if either path cannot be resolved (e.g. doesn't exist).
+ */
+function isSamePath(a: string, b: string): boolean {
+  try {
+    return realpathSync(a) === realpathSync(b);
+  } catch {
+    return false;
+  }
+}
+
 // ─── Module State ──────────────────────────────────────────────────────────
 
 /** Original project root before chdir into auto-worktree. */
@@ -119,6 +152,227 @@ function clearProjectRootStateFiles(basePath: string, milestoneId: string): void
     }
   }
 }
+
+// ─── Dispatch-Level Sync (project root ↔ worktree) ──────────────────────────
+
+/**
+ * Sync milestone artifacts from project root INTO worktree before deriveState.
+ * Covers the case where the LLM wrote artifacts to the main repo filesystem
+ * (e.g. via absolute paths) but the worktree has stale data. Also deletes
+ * gsd.db in the worktree so it rebuilds from fresh disk state (#853).
+ * Non-fatal — sync failure should never block dispatch.
+ */
+export function syncProjectRootToWorktree(
+  projectRoot: string,
+  worktreePath_: string,
+  milestoneId: string | null,
+): void {
+  if (!worktreePath_ || !projectRoot || worktreePath_ === projectRoot) return;
+  if (!milestoneId) return;
+
+  const prGsd = join(projectRoot, ".gsd");
+  const wtGsd = join(worktreePath_, ".gsd");
+
+  // Copy milestone directory from project root to worktree — additive only.
+  // force:false prevents cpSync from overwriting existing worktree files.
+  // Without this, worktree-authoritative files (e.g. VALIDATION.md written
+  // by validate-milestone) get clobbered by stale project root copies,
+  // causing an infinite re-validation loop (#1886).
+  safeCopyRecursive(
+    join(prGsd, "milestones", milestoneId),
+    join(wtGsd, "milestones", milestoneId),
+    { force: false },
+  );
+
+  // Forward-sync completed-units.json from project root to worktree.
+  // Project root is authoritative for completion state after crash recovery;
+  // without this, the worktree re-dispatches already-completed units (#1886).
+  safeCopy(
+    join(prGsd, "completed-units.json"),
+    join(wtGsd, "completed-units.json"),
+    { force: true },
+  );
+
+  // Delete worktree gsd.db so it rebuilds from the freshly synced files.
+  // Stale DB rows are the root cause of the infinite skip loop (#853).
+  try {
+    const wtDb = join(wtGsd, "gsd.db");
+    if (existsSync(wtDb)) {
+      unlinkSync(wtDb);
+    }
+  } catch {
+    /* non-fatal */
+  }
+}
+
+/**
+ * Sync dispatch-critical .gsd/ state files from worktree to project root.
+ * Only runs when inside an auto-worktree (worktreePath differs from projectRoot).
+ * Copies: STATE.md + active milestone directory (roadmap, slice plans, task summaries).
+ * Non-fatal — sync failure should never block dispatch.
+ */
+export function syncStateToProjectRoot(
+  worktreePath_: string,
+  projectRoot: string,
+  milestoneId: string | null,
+): void {
+  if (!worktreePath_ || !projectRoot || worktreePath_ === projectRoot) return;
+  if (!milestoneId) return;
+
+  const wtGsd = join(worktreePath_, ".gsd");
+  const prGsd = join(projectRoot, ".gsd");
+
+  // 1. STATE.md — the quick-glance status used by initial deriveState()
+  safeCopy(join(wtGsd, "STATE.md"), join(prGsd, "STATE.md"), { force: true });
+
+  // 2. Milestone directory — ROADMAP, slice PLANs, task summaries
+  // Copy the entire milestone .gsd subtree so deriveState reads current checkboxes
+  safeCopyRecursive(
+    join(wtGsd, "milestones", milestoneId),
+    join(prGsd, "milestones", milestoneId),
+    { force: true },
+  );
+
+  // 3. metrics.json — session cost/token tracking (#2313).
+  // Without this, metrics accumulated in the worktree are invisible from the
+  // project root and never appear in the dashboard or skill-health reports.
+  safeCopy(join(wtGsd, "metrics.json"), join(prGsd, "metrics.json"), { force: true });
+
+  // 4. Runtime records — unit dispatch state used by selfHealRuntimeRecords().
+  // Without this, a crash during a unit leaves the runtime record only in the
+  // worktree. If the next session resolves basePath before worktree re-entry,
+  // selfHeal can't find or clear the stale record (#769).
+  safeCopyRecursive(
+    join(wtGsd, "runtime", "units"),
+    join(prGsd, "runtime", "units"),
+    { force: true },
+  );
+}
+
+// ─── Resource Staleness ───────────────────────────────────────────────────
+
+/**
+ * Read the resource version (semver) from the managed-resources manifest.
+ * Uses gsdVersion instead of syncedAt so that launching a second session
+ * doesn't falsely trigger staleness (#804).
+ */
+export function readResourceVersion(): string | null {
+  const agentDir =
+    process.env.GSD_CODING_AGENT_DIR || join(gsdHome, "agent");
+  const manifestPath = join(agentDir, "managed-resources.json");
+  try {
+    const manifest = JSON.parse(readFileSync(manifestPath, "utf-8"));
+    return typeof manifest?.gsdVersion === "string"
+      ? manifest.gsdVersion
+      : null;
+  } catch {
+    return null;
+  }
+}
+
+/**
+ * Check if managed resources have been updated since session start.
+ * Returns a warning message if stale, null otherwise.
+ */
+export function checkResourcesStale(
+  versionOnStart: string | null,
+): string | null {
+  if (versionOnStart === null) return null;
+  const current = readResourceVersion();
+  if (current === null) return null;
+  if (current !== versionOnStart) {
+    return "GSD resources were updated since this session started. Restart gsd to load the new code.";
+  }
+  return null;
+}
+
+// ─── Stale Worktree Escape ────────────────────────────────────────────────
+
+/**
+ * Detect and escape a stale worktree cwd (#608).
+ *
+ * After milestone completion + merge, the worktree directory is removed but
+ * the process cwd may still point inside `.gsd/worktrees/<MID>/`.
+ * When a new session starts, `process.cwd()` is passed as `base` to startAuto
+ * and all subsequent writes land in the wrong directory. This function detects
+ * that scenario and chdir back to the project root.
+ *
+ * Returns the corrected base path.
+ */
+export function escapeStaleWorktree(base: string): string {
+  // Direct layout: /.gsd/worktrees/
+  const directMarker = `${pathSep}.gsd${pathSep}worktrees${pathSep}`;
+  let idx = base.indexOf(directMarker);
+  if (idx === -1) {
+    // Symlink-resolved layout: /.gsd/projects/<hash>/worktrees/
+    const symlinkRe = new RegExp(
+      `\\${pathSep}\\.gsd\\${pathSep}projects\\${pathSep}[a-f0-9]+\\${pathSep}worktrees\\${pathSep}`,
+    );
+    const match = base.match(symlinkRe);
+    if (!match || match.index === undefined) return base;
+    idx = match.index;
+  }
+
+  // base is inside .gsd/worktrees/<something> — extract the project root
+  const projectRoot = base.slice(0, idx);
+
+  // Guard: If the candidate project root's .gsd IS the user-level ~/.gsd,
+  // the string-slice heuristic matched the wrong /.gsd/ boundary. This happens
+  // when .gsd is a symlink into ~/.gsd/projects/<hash> and process.cwd()
+  // resolved through the symlink. Returning ~ would be catastrophic (#1676).
+  const candidateGsd = join(projectRoot, ".gsd").replaceAll("\\", "/");
+  const gsdHomePath = gsdHome.replaceAll("\\", "/");
+  if (candidateGsd === gsdHomePath || candidateGsd.startsWith(gsdHomePath + "/")) {
+    // Don't chdir to home — return base unchanged.
+    // resolveProjectRoot() in worktree.ts has the full git-file-based recovery
+    // and will be called by the caller (startAuto → projectRoot()).
+    return base;
+  }
+
+  try {
+    process.chdir(projectRoot);
+  } catch {
+    // If chdir fails, return the original — caller will handle errors downstream
+    return base;
+  }
+  return projectRoot;
+}
+
+/**
+ * Clean stale runtime unit files for completed milestones.
+ *
+ * After restart, stale runtime/units/*.json from prior milestones can
+ * cause deriveState to resume the wrong milestone (#887). Removes files
+ * for milestones that have a SUMMARY (fully complete).
+ */
+export function cleanStaleRuntimeUnits(
+  gsdRootPath: string,
+  hasMilestoneSummary: (mid: string) => boolean,
+): number {
+  const runtimeUnitsDir = join(gsdRootPath, "runtime", "units");
+  if (!existsSync(runtimeUnitsDir)) return 0;
+
+  let cleaned = 0;
+  try {
+    for (const file of readdirSync(runtimeUnitsDir)) {
+      if (!file.endsWith(".json")) continue;
+      const midMatch = file.match(/(M\d+(?:-[a-z0-9]{6})?)/);
+      if (!midMatch) continue;
+      if (hasMilestoneSummary(midMatch[1])) {
+        try {
+          unlinkSync(join(runtimeUnitsDir, file));
+          cleaned++;
+        } catch {
+          /* non-fatal */
+        }
+      }
+    }
+  } catch {
+    /* non-fatal */
+  }
+  return cleaned;
+}
+
 // ─── Worktree ↔ Main Repo Sync (#1311) ──────────────────────────────────────
 
 /**
@@ -144,28 +398,12 @@ export function syncGsdStateToWorktree(
   const synced: string[] = [];
 
   // If both resolve to the same directory (symlink), no sync needed
-  try {
-    const mainResolved = realpathSync(mainGsd);
-    const wtResolved = realpathSync(wtGsd);
-    if (mainResolved === wtResolved) return { synced };
-  } catch {
-    // Can't resolve — proceed with sync as a safety measure
-  }
+  if (isSamePath(mainGsd, wtGsd)) return { synced };
 
   if (!existsSync(mainGsd) || !existsSync(wtGsd)) return { synced };
 
   // Sync root-level .gsd/ files (DECISIONS, REQUIREMENTS, PROJECT, KNOWLEDGE, etc.)
-  const rootFiles = [
-    "DECISIONS.md",
-    "REQUIREMENTS.md",
-    "PROJECT.md",
-    "KNOWLEDGE.md",
-    "OVERRIDES.md",
-    "QUEUE.md",
-    "completed-units.json",
-    "metrics.json",
-  ];
-  for (const f of rootFiles) {
+  for (const f of ROOT_STATE_FILES) {
     const src = join(mainGsd, f);
     const dst = join(wtGsd, f);
     if (existsSync(src) && !existsSync(dst)) {
@@ -298,13 +536,7 @@ export function syncWorktreeStateBack(
   const synced: string[] = [];
 
   // If both resolve to the same directory (symlink), no sync needed
-  try {
-    const mainResolved = realpathSync(mainGsd);
-    const wtResolved = realpathSync(wtGsd);
-    if (mainResolved === wtResolved) return { synced };
-  } catch {
-    // Can't resolve — proceed with sync
-  }
+  if (isSamePath(mainGsd, wtGsd)) return { synced };
 
   if (!existsSync(wtGsd) || !existsSync(mainGsd)) return { synced };
 
@@ -330,17 +562,7 @@ export function syncWorktreeStateBack(
   // Also includes QUEUE.md, completed-units.json, and metrics.json which are
   // written during milestone closeout and lost on teardown without explicit sync
   // (#1787, #2313).
-  const rootFiles = [
-    "DECISIONS.md",
-    "REQUIREMENTS.md",
-    "PROJECT.md",
-    "KNOWLEDGE.md",
-    "OVERRIDES.md",
-    "QUEUE.md",
-    "completed-units.json",
-    "metrics.json",
-  ];
-  for (const f of rootFiles) {
+  for (const f of ROOT_STATE_FILES) {
     const src = join(wtGsd, f);
     const dst = join(mainGsd, f);
     if (existsSync(src)) {
diff --git a/src/resources/extensions/gsd/auto.ts b/src/resources/extensions/gsd/auto.ts
index 062715bbd..8c696bd42 100644
--- a/src/resources/extensions/gsd/auto.ts
+++ b/src/resources/extensions/gsd/auto.ts
@@ -76,13 +76,6 @@ import {
 import { closeoutUnit } from "./auto-unit-closeout.js";
 import { recoverTimedOutUnit } from "./auto-timeout-recovery.js";
 import { selectAndApplyModel, resolveModelId } from "./auto-model-selection.js";
-import {
-  syncProjectRootToWorktree,
-  syncStateToProjectRoot,
-  readResourceVersion,
-  checkResourcesStale,
-  escapeStaleWorktree,
-} from "./auto-worktree-sync.js";
 import { resetRoutingHistory, recordOutcome } from "./routing-history.js";
 import {
   checkPostUnitHooks,
@@ -143,6 +136,11 @@ import {
   mergeMilestoneToMain,
   autoWorktreeBranch,
   syncWorktreeStateBack,
+  syncProjectRootToWorktree,
+  syncStateToProjectRoot,
+  readResourceVersion,
+  checkResourcesStale,
+  escapeStaleWorktree,
 } from "./auto-worktree.js";
 import { pruneQueueOrder } from "./queue-order.js";
 
@@ -190,8 +188,6 @@ import {
 } from "./worktree-resolver.js";
 import { reorderForCaching } from "./prompt-ordering.js";
 
-// Worktree sync, resource staleness, stale worktree escape → auto-worktree-sync.ts
-
 // ─── Session State ─────────────────────────────────────────────────────────
 
 import {
diff --git a/src/resources/extensions/gsd/prompts/forensics.md b/src/resources/extensions/gsd/prompts/forensics.md
index 9112a773f..0ea3ce71c 100644
--- a/src/resources/extensions/gsd/prompts/forensics.md
+++ b/src/resources/extensions/gsd/prompts/forensics.md
@@ -16,7 +16,7 @@ GSD extension source code is at: `{{gsdSourceDir}}`
 
 | Domain | Files |
 |--------|-------|
-| **Auto-mode engine** | `auto.ts` `auto-loop.ts` `auto-dispatch.ts` `auto-start.ts` `auto-supervisor.ts` `auto-timers.ts` `auto-timeout-recovery.ts` `auto-unit-closeout.ts` `auto-post-unit.ts` `auto-verification.ts` `auto-recovery.ts` `auto-worktree.ts` `auto-worktree-sync.ts` `auto-model-selection.ts` `auto-budget.ts` `dispatch-guard.ts` |
+| **Auto-mode engine** | `auto.ts` `auto-loop.ts` `auto-dispatch.ts` `auto-start.ts` `auto-supervisor.ts` `auto-timers.ts` `auto-timeout-recovery.ts` `auto-unit-closeout.ts` `auto-post-unit.ts` `auto-verification.ts` `auto-recovery.ts` `auto-worktree.ts` `auto-model-selection.ts` `auto-budget.ts` `dispatch-guard.ts` |
 | **State & persistence** | `state.ts` `types.ts` `files.ts` `paths.ts` `json-persistence.ts` `atomic-write.ts` |
 | **Forensics & recovery** | `forensics.ts` `session-forensics.ts` `crash-recovery.ts` `session-lock.ts` |
 | **Metrics & telemetry** | `metrics.ts` `skill-telemetry.ts` `token-counter.ts` |
diff --git a/src/resources/extensions/gsd/tests/completed-units-metrics-sync.test.ts b/src/resources/extensions/gsd/tests/completed-units-metrics-sync.test.ts
index 4c451bece..46da65fa6 100644
--- a/src/resources/extensions/gsd/tests/completed-units-metrics-sync.test.ts
+++ b/src/resources/extensions/gsd/tests/completed-units-metrics-sync.test.ts
@@ -48,35 +48,32 @@ test("#2313: completed-units.json should not be blindly wiped to [] on milestone
 // ─── Bug 2: metrics.json should be in the sync file lists ──────────────────
 
 test("#2313: syncStateToProjectRoot should sync metrics.json", () => {
-  const syncSrcPath = join(import.meta.dirname, "..", "auto-worktree-sync.ts");
+  const syncSrcPath = join(import.meta.dirname, "..", "auto-worktree.ts");
   const syncSrc = readFileSync(syncSrcPath, "utf-8");
 
   // syncStateToProjectRoot should copy metrics.json from worktree to project root
   assert.ok(
     syncSrc.includes("metrics.json"),
-    "auto-worktree-sync.ts should reference metrics.json for sync",
+    "auto-worktree.ts should reference metrics.json for sync",
   );
 });
 
-test("#2313: syncWorktreeStateBack should include metrics.json in root files list", () => {
+test("#2313: syncWorktreeStateBack should include metrics.json in ROOT_STATE_FILES", () => {
   const autoWorktreeSrcPath = join(import.meta.dirname, "..", "auto-worktree.ts");
   const autoWorktreeSrc = readFileSync(autoWorktreeSrcPath, "utf-8");
 
-  // Find the rootFiles array in syncWorktreeStateBack
-  const syncBackIdx = autoWorktreeSrc.indexOf("syncWorktreeStateBack");
-  assert.ok(syncBackIdx !== -1, "syncWorktreeStateBack exists");
+  // Find the ROOT_STATE_FILES constant (single source of truth for both sync directions)
+  const constIdx = autoWorktreeSrc.indexOf("ROOT_STATE_FILES");
+  assert.ok(constIdx !== -1, "ROOT_STATE_FILES constant exists");
 
-  const rootFilesIdx = autoWorktreeSrc.indexOf("rootFiles", syncBackIdx);
-  assert.ok(rootFilesIdx !== -1, "rootFiles list exists in syncWorktreeStateBack");
-
-  // Get the rootFiles array content
-  const arrayStart = autoWorktreeSrc.indexOf("[", rootFilesIdx);
+  // Get the array content
+  const arrayStart = autoWorktreeSrc.indexOf("[", constIdx);
   const arrayEnd = autoWorktreeSrc.indexOf("]", arrayStart);
   const rootFilesBlock = autoWorktreeSrc.slice(arrayStart, arrayEnd);
 
   assert.ok(
     rootFilesBlock.includes("metrics.json"),
-    "metrics.json should be in syncWorktreeStateBack rootFiles list",
+    "metrics.json should be in ROOT_STATE_FILES list",
   );
 });
 
diff --git a/src/resources/extensions/gsd/tests/worktree-sync-milestones.test.ts b/src/resources/extensions/gsd/tests/worktree-sync-milestones.test.ts
index 0df83dfd2..94cebb383 100644
--- a/src/resources/extensions/gsd/tests/worktree-sync-milestones.test.ts
+++ b/src/resources/extensions/gsd/tests/worktree-sync-milestones.test.ts
@@ -27,7 +27,7 @@ import { mkdtempSync, mkdirSync, writeFileSync, rmSync, existsSync, readFileSync
 import { join } from 'node:path';
 import { tmpdir } from 'node:os';
 
-import { syncProjectRootToWorktree } from '../auto-worktree-sync.ts';
+import { syncProjectRootToWorktree } from '../auto-worktree.ts';
 import { syncGsdStateToWorktree, syncWorktreeStateBack } from '../auto-worktree.ts';
 import { describe, test } from 'node:test';
 import assert from 'node:assert/strict';
diff --git a/src/resources/extensions/gsd/tests/worktree-sync-overwrite-loop.test.ts b/src/resources/extensions/gsd/tests/worktree-sync-overwrite-loop.test.ts
index 211c87d8d..fd297b5ee 100644
--- a/src/resources/extensions/gsd/tests/worktree-sync-overwrite-loop.test.ts
+++ b/src/resources/extensions/gsd/tests/worktree-sync-overwrite-loop.test.ts
@@ -29,7 +29,7 @@ import {
 import { join } from "node:path";
 import { tmpdir } from "node:os";
 
-import { syncProjectRootToWorktree } from "../auto-worktree-sync.ts";
+import { syncProjectRootToWorktree } from "../auto-worktree.ts";
 import { createTestContext } from "./test-helpers.ts";
 
 const { assertTrue, assertEq, report } = createTestContext();