diff --git a/src/resources/extensions/gsd/doctor-checks.ts b/src/resources/extensions/gsd/doctor-checks.ts
index 923b68675..d9a26e66c 100644
--- a/src/resources/extensions/gsd/doctor-checks.ts
+++ b/src/resources/extensions/gsd/doctor-checks.ts
@@ -1,1298 +1,5 @@
-import { existsSync, lstatSync, readdirSync, readFileSync, realpathSync, rmSync, statSync } from "node:fs";
-import { basename, dirname, join, sep } from "node:path";
-
-import type { DoctorIssue, DoctorIssueCode } from "./doctor-types.js";
-import { readRepoMeta, externalProjectsRoot, cleanNumberedGsdVariants } from "./repo-identity.js";
-import { loadFile } from "./files.js";
-import { parseRoadmap as parseLegacyRoadmap } from "./parsers-legacy.js";
-import { isDbAvailable, _getAdapter, getMilestoneSlices } from "./gsd-db.js";
-import { resolveMilestoneFile, milestonesDir, gsdRoot, resolveGsdRootFile, relGsdRootFile } from "./paths.js";
-import { deriveState, isMilestoneComplete } from "./state.js";
-import { saveFile } from "./files.js";
-import { listWorktrees, resolveGitDir, worktreesDir } from "./worktree-manager.js";
-import { abortAndReset } from "./git-self-heal.js";
-import { RUNTIME_EXCLUSION_PATHS, resolveMilestoneIntegrationBranch, writeIntegrationBranch } from "./git-service.js";
-import { nativeIsRepo, nativeBranchExists, nativeWorktreeList, nativeWorktreeRemove, nativeBranchList, nativeBranchDelete, nativeLsFiles, nativeRmCached, nativeForEachRef, nativeUpdateRef } from "./native-git-bridge.js";
-import { readCrashLock, isLockProcessAlive, clearLock } from "./crash-recovery.js";
-import { ensureGitignore } from "./gitignore.js";
-import { getAllWorktreeHealth } from "./worktree-health.js";
-import { readAllSessionStatuses, isSessionStale, removeSessionStatus } from "./session-status-io.js";
-import { recoverFailedMigration } from "./migrate-external.js";
-import { loadEffectiveGSDPreferences } from "./preferences.js";
-import { readEvents } from "./workflow-events.js";
-import { renderAllProjections } from "./workflow-projections.js";
-
-export async function checkGitHealth(
-  basePath: string,
-  issues: DoctorIssue[],
-  fixesApplied: string[],
-  shouldFix: (code: DoctorIssueCode) => boolean,
-  isolationMode: "none" | "worktree" | "branch" = "none",
-): Promise<void> {
-  // Degrade gracefully if not a git repo
-  if (!nativeIsRepo(basePath)) {
-    return; // Not a git repo — skip all git health checks
-  }
-
-  const gitDir = resolveGitDir(basePath);
-
-  // ── Orphaned auto-worktrees & Stale milestone branches ────────────────
-  // These checks only apply in worktree/branch modes — skip in none mode
-  // where no milestone worktrees or branches are created.
-  if (isolationMode !== "none") {
-  try {
-    const worktrees = listWorktrees(basePath);
-    const milestoneWorktrees = worktrees.filter(wt => wt.branch.startsWith("milestone/"));
-
-    // Load roadmap state once for cross-referencing
-    const state = await deriveState(basePath);
-
-    for (const wt of milestoneWorktrees) {
-      // Extract milestone ID from branch name "milestone/M001" → "M001"
-      const milestoneId = wt.branch.replace(/^milestone\//, "");
-      const milestoneEntry = state.registry.find(m => m.id === milestoneId);
-
-      // Check if milestone is complete via roadmap
-      let isComplete = false;
-      if (milestoneEntry) {
-        if (isDbAvailable()) {
-          const dbSlices = getMilestoneSlices(milestoneId);
-          isComplete = dbSlices.length > 0 && dbSlices.every(s => s.status === "complete");
-        } else {
-          const roadmapPath = resolveMilestoneFile(basePath, milestoneId, "ROADMAP");
-          const roadmapContent = roadmapPath ? await loadFile(roadmapPath) : null;
-          if (roadmapContent) {
-            const roadmap = parseLegacyRoadmap(roadmapContent);
-            isComplete = isMilestoneComplete(roadmap);
-          }
-        }
-        // When DB unavailable and no roadmap, isComplete stays false
-      }
-
-      if (isComplete) {
-        issues.push({
-          severity: "warning",
-          code: "orphaned_auto_worktree",
-          scope: "milestone",
-          unitId: milestoneId,
-          message: `Worktree for completed milestone ${milestoneId} still exists at ${wt.path}`,
-          fixable: true,
-        });
-
-        if (shouldFix("orphaned_auto_worktree")) {
-          // If cwd is inside the worktree, chdir out first — matching the
-          // pattern in removeWorktree() (#1946). Without this, git cannot
-          // remove the worktree and the doctor enters a deadlock where it
-          // detects the orphan every run but never cleans it up.
-          const cwd = process.cwd();
-          if (wt.path === cwd || cwd.startsWith(wt.path + sep)) {
-            try {
-              process.chdir(basePath);
-            } catch {
-              fixesApplied.push(`skipped removing worktree at ${wt.path} (cannot chdir to basePath)`);
-              continue;
-            }
-          }
-          try {
-            nativeWorktreeRemove(basePath, wt.path, true);
-            fixesApplied.push(`removed orphaned worktree ${wt.path}`);
-          } catch {
-            fixesApplied.push(`failed to remove worktree ${wt.path}`);
-          }
-        }
-      }
-    }
-
-    // ── Stale milestone branches ─────────────────────────────────────────
-    try {
-      const branches = nativeBranchList(basePath, "milestone/*");
-      if (branches.length > 0) {
-        const worktreeBranches = new Set(milestoneWorktrees.map(wt => wt.branch));
-
-        for (const branch of branches) {
-          // Skip branches that have a worktree (handled above)
-          if (worktreeBranches.has(branch)) continue;
-
-          const milestoneId = branch.replace(/^milestone\//, "");
-          const roadmapPath = resolveMilestoneFile(basePath, milestoneId, "ROADMAP");
-          let branchMilestoneComplete = false;
-          if (isDbAvailable()) {
-            const dbSlices = getMilestoneSlices(milestoneId);
-            branchMilestoneComplete = dbSlices.length > 0 && dbSlices.every(s => s.status === "complete");
-          } else {
-            const roadmapContent = roadmapPath ? await loadFile(roadmapPath) : null;
-            if (!roadmapContent) continue;
-            const roadmap = parseLegacyRoadmap(roadmapContent);
-            branchMilestoneComplete = isMilestoneComplete(roadmap);
-          }
-          if (branchMilestoneComplete) {
-            issues.push({
-              severity: "info",
-              code: "stale_milestone_branch",
-              scope: "milestone",
-              unitId: milestoneId,
-              message: `Branch ${branch} exists for completed milestone ${milestoneId}`,
-              fixable: true,
-            });
-
-            if (shouldFix("stale_milestone_branch")) {
-              try {
-                nativeBranchDelete(basePath, branch, true);
-                fixesApplied.push(`deleted stale branch ${branch}`);
-              } catch {
-                fixesApplied.push(`failed to delete branch ${branch}`);
-              }
-            }
-          }
-        }
-      }
-    } catch {
-      // git branch list failed — skip stale branch check
-    }
-  } catch {
-    // listWorktrees or deriveState failed — skip worktree/branch checks
-  }
-  } // end isolationMode !== "none"
-
-  // ── Corrupt merge state ────────────────────────────────────────────────
-  try {
-    const mergeStateFiles = ["MERGE_HEAD", "SQUASH_MSG"];
-    const mergeStateDirs = ["rebase-apply", "rebase-merge"];
-    const found: string[] = [];
-
-    for (const f of mergeStateFiles) {
-      if (existsSync(join(gitDir, f))) found.push(f);
-    }
-    for (const d of mergeStateDirs) {
-      if (existsSync(join(gitDir, d))) found.push(d);
-    }
-
-    if (found.length > 0) {
-      issues.push({
-        severity: "error",
-        code: "corrupt_merge_state",
-        scope: "project",
-        unitId: "project",
-        message: `Corrupt merge/rebase state detected: ${found.join(", ")}`,
-        fixable: true,
-      });
-
-      if (shouldFix("corrupt_merge_state")) {
-        const result = abortAndReset(basePath);
-        fixesApplied.push(`cleaned merge state: ${result.cleaned.join(", ")}`);
-      }
-    }
-  } catch {
-    // Can't check .git dir — skip
-  }
-
-  // ── Tracked runtime files ──────────────────────────────────────────────
-  try {
-    const trackedPaths: string[] = [];
-    for (const exclusion of RUNTIME_EXCLUSION_PATHS) {
-      try {
-        const files = nativeLsFiles(basePath, exclusion);
-        if (files.length > 0) {
-          trackedPaths.push(...files);
-        }
-      } catch {
-        // Individual ls-files can fail — continue
-      }
-    }
-
-    if (trackedPaths.length > 0) {
-      issues.push({
-        severity: "warning",
-        code: "tracked_runtime_files",
-        scope: "project",
-        unitId: "project",
-        message: `${trackedPaths.length} runtime file(s) are tracked by git: ${trackedPaths.slice(0, 5).join(", ")}${trackedPaths.length > 5 ? "..." : ""}`,
-        fixable: true,
-      });
-
-      if (shouldFix("tracked_runtime_files")) {
-        try {
-          for (const exclusion of RUNTIME_EXCLUSION_PATHS) {
-            nativeRmCached(basePath, [exclusion]);
-          }
-          fixesApplied.push(`untracked ${trackedPaths.length} runtime file(s)`);
-        } catch {
-          fixesApplied.push("failed to untrack runtime files");
-        }
-      }
-    }
-  } catch {
-    // git ls-files failed — skip
-  }
-
-  // ── Legacy slice branches ──────────────────────────────────────────────
-  try {
-    const branchList = nativeBranchList(basePath, "gsd/*/*")
-      .filter((branch) => !branch.startsWith("gsd/quick/"));
-    if (branchList.length > 0) {
-      issues.push({
-        severity: "info",
-        code: "legacy_slice_branches",
-        scope: "project",
-        unitId: "project",
-        message: `${branchList.length} legacy slice branch(es) found: ${branchList.slice(0, 3).join(", ")}${branchList.length > 3 ? "..." : ""}. These are no longer used (branchless architecture).`,
-        fixable: true,
-      });
-
-      if (shouldFix("legacy_slice_branches")) {
-        let deleted = 0;
-        for (const branch of branchList) {
-          try {
-            nativeBranchDelete(basePath, branch, true);
-            deleted++;
-          } catch { /* skip branches that can't be deleted */ }
-        }
-        if (deleted > 0) {
-          fixesApplied.push(`deleted ${deleted} legacy slice branch(es)`);
-        }
-      }
-    }
-  } catch {
-    // git branch list failed — skip
-  }
-
-  // ── Integration branch existence ──────────────────────────────────────
-  // For each active (non-complete) milestone, verify the stored integration
-  // branch still exists in git. A missing integration branch blocks merge-back
-  // and causes the next merge operation to fail silently.
-  try {
-    const state = await deriveState(basePath);
-    const gitPrefs = loadEffectiveGSDPreferences()?.preferences?.git ?? {};
-    for (const milestone of state.registry) {
-      if (milestone.status === "complete") continue;
-      const resolution = resolveMilestoneIntegrationBranch(basePath, milestone.id, gitPrefs);
-      if (!resolution.recordedBranch) continue; // No stored branch — skip (not yet set)
-      if (resolution.status === "fallback" && resolution.effectiveBranch) {
-        issues.push({
-          severity: "warning",
-          code: "integration_branch_missing",
-          scope: "milestone",
-          unitId: milestone.id,
-          message: resolution.reason,
-          fixable: true,
-        });
-        if (shouldFix("integration_branch_missing")) {
-          writeIntegrationBranch(basePath, milestone.id, resolution.effectiveBranch);
-          fixesApplied.push(`updated integration branch for ${milestone.id} to "${resolution.effectiveBranch}"`);
-        }
-        continue;
-      }
-
-      if (resolution.status === "missing") {
-        issues.push({
-          severity: "error",
-          code: "integration_branch_missing",
-          scope: "milestone",
-          unitId: milestone.id,
-          message: resolution.reason,
-          fixable: false,
-        });
-      }
-    }
-  } catch {
-    // Non-fatal — integration branch check failed
-  }
-
-  // ── Orphaned worktree directories ────────────────────────────────────
-  // Worktree removal can fail after a branch delete, leaving a directory
-  // that is no longer registered with git. These orphaned dirs cause
-  // "already exists" errors when re-creating the same worktree name.
-  try {
-    const wtDir = worktreesDir(basePath);
-    if (existsSync(wtDir)) {
-      // Resolve symlinks and normalize separators so that symlinked .gsd
-      // paths (e.g. ~/.gsd/projects/<hash>/worktrees/…) match the paths
-      // returned by `git worktree list`.
-      const normalizePath = (p: string): string => {
-        try { p = realpathSync(p); } catch { /* path may not exist */ }
-        return p.replaceAll("\\", "/");
-      };
-      const registeredPaths = new Set(
-        nativeWorktreeList(basePath).map(entry => normalizePath(entry.path)),
-      );
-      for (const entry of readdirSync(wtDir)) {
-        const fullPath = join(wtDir, entry);
-        try {
-          if (!statSync(fullPath).isDirectory()) continue;
-        } catch { continue; }
-        const normalizedFullPath = normalizePath(fullPath);
-        if (!registeredPaths.has(normalizedFullPath)) {
-          issues.push({
-            severity: "warning",
-            code: "worktree_directory_orphaned",
-            scope: "project",
-            unitId: entry,
-            message: `Worktree directory ${fullPath} exists on disk but is not registered with git. Run "git worktree prune" or doctor --fix to remove it.`,
-            fixable: true,
-          });
-          if (shouldFix("worktree_directory_orphaned")) {
-            try {
-              rmSync(fullPath, { recursive: true, force: true });
-              fixesApplied.push(`removed orphaned worktree directory ${fullPath}`);
-            } catch {
-              fixesApplied.push(`failed to remove orphaned worktree directory ${fullPath}`);
-            }
-          }
-        }
-      }
-    }
-  } catch {
-    // Non-fatal — orphaned worktree directory check failed
-  }
-
-  // ── Worktree lifecycle checks ──────────────────────────────────────────
-  // Check GSD-managed worktrees for: merged branches, stale work, dirty
-  // state, and unpushed commits. Only worktrees under .gsd/worktrees/.
-  try {
-    const healthStatuses = getAllWorktreeHealth(basePath);
-    const cwd = process.cwd();
-
-    for (const health of healthStatuses) {
-      const wt = health.worktree;
-      const isCwd = wt.path === cwd || cwd.startsWith(wt.path + sep);
-
-      // Branch fully merged into main — safe to remove
-      if (health.mergedIntoMain) {
-        issues.push({
-          severity: "info",
-          code: "worktree_branch_merged",
-          scope: "project",
-          unitId: wt.name,
-          message: `Worktree "${wt.name}" (branch ${wt.branch}) is fully merged into main${health.safeToRemove ? " — safe to remove" : ""}`,
-          fixable: health.safeToRemove,
-        });
-
-        if (health.safeToRemove && shouldFix("worktree_branch_merged") && !isCwd) {
-          try {
-            const { removeWorktree } = await import("./worktree-manager.js");
-            removeWorktree(basePath, wt.name, { deleteBranch: true, branch: wt.branch });
-            fixesApplied.push(`removed merged worktree "${wt.name}" and deleted branch ${wt.branch}`);
-          } catch {
-            fixesApplied.push(`failed to remove merged worktree "${wt.name}"`);
-          }
-        }
-        // If merged, skip the stale/dirty/unpushed checks — they're irrelevant
-        continue;
-      }
-
-      // Stale: no commits in N days, not merged
-      if (health.stale) {
-        const days = Math.floor(health.lastCommitAgeDays);
-        issues.push({
-          severity: "warning",
-          code: "worktree_stale",
-          scope: "project",
-          unitId: wt.name,
-          message: `Worktree "${wt.name}" has had no commits in ${days} day${days === 1 ? "" : "s"}`,
-          fixable: false,
-        });
-      }
-
-      // Dirty: uncommitted changes in a worktree (only flag on stale worktrees to avoid noise)
-      if (health.dirty && health.stale) {
-        issues.push({
-          severity: "warning",
-          code: "worktree_dirty",
-          scope: "project",
-          unitId: wt.name,
-          message: `Worktree "${wt.name}" has ${health.dirtyFileCount} uncommitted file${health.dirtyFileCount === 1 ? "" : "s"} and is stale`,
-          fixable: false,
-        });
-      }
-
-      // Unpushed: commits not on any remote (only flag on stale worktrees to avoid noise)
-      if (health.unpushedCommits > 0 && health.stale) {
-        issues.push({
-          severity: "warning",
-          code: "worktree_unpushed",
-          scope: "project",
-          unitId: wt.name,
-          message: `Worktree "${wt.name}" has ${health.unpushedCommits} unpushed commit${health.unpushedCommits === 1 ? "" : "s"}`,
-          fixable: false,
-        });
-      }
-    }
-  } catch {
-    // Non-fatal — worktree lifecycle check failed
-  }
-}
-
-// ── Runtime Health Checks ──────────────────────────────────────────────────
-// Checks for stale crash locks, orphaned completed-units, stale hook state,
-// activity log bloat, STATE.md drift, and gitignore drift.
-
-export async function checkRuntimeHealth(
-  basePath: string,
-  issues: DoctorIssue[],
-  fixesApplied: string[],
-  shouldFix: (code: DoctorIssueCode) => boolean,
-): Promise<void> {
-  const root = gsdRoot(basePath);
-
-  // ── Stale crash lock ──────────────────────────────────────────────────
-  try {
-    const lock = readCrashLock(basePath);
-    if (lock) {
-      const alive = isLockProcessAlive(lock);
-      if (!alive) {
-        issues.push({
-          severity: "error",
-          code: "stale_crash_lock",
-          scope: "project",
-          unitId: "project",
-          message: `Stale auto.lock from PID ${lock.pid} (started ${lock.startedAt}, was executing ${lock.unitType} ${lock.unitId}) — process is no longer running`,
-          file: ".gsd/auto.lock",
-          fixable: true,
-        });
-
-        if (shouldFix("stale_crash_lock")) {
-          clearLock(basePath);
-          fixesApplied.push("cleared stale auto.lock");
-        }
-      }
-    }
-  } catch {
-    // Non-fatal — crash lock check failed
-  }
-
-  // ── Stranded lock directory ────────────────────────────────────────────
-  // proper-lockfile creates a `.gsd.lock/` directory as the OS-level lock
-  // mechanism. If the process was SIGKILLed or crashed hard, this directory
-  // can remain on disk without any live process holding it. The next session
-  // fails to acquire the lock until the directory is removed (#1245).
-  try {
-    const lockDir = join(dirname(root), `${basename(root)}.lock`);
-    if (existsSync(lockDir)) {
-      const statRes = statSync(lockDir);
-      if (statRes.isDirectory()) {
-        // Check if any live process actually holds this lock
-        const lock = readCrashLock(basePath);
-        const lockHolderAlive = lock ? isLockProcessAlive(lock) : false;
-        if (!lockHolderAlive) {
-          issues.push({
-            severity: "error",
-            code: "stranded_lock_directory",
-            scope: "project",
-            unitId: "project",
-            message: `Stranded lock directory "${lockDir}" exists but no live process holds the session lock. This blocks new auto-mode sessions from starting.`,
-            file: lockDir,
-            fixable: true,
-          });
-          if (shouldFix("stranded_lock_directory")) {
-            try {
-              rmSync(lockDir, { recursive: true, force: true });
-              fixesApplied.push(`removed stranded lock directory ${lockDir}`);
-            } catch {
-              fixesApplied.push(`failed to remove stranded lock directory ${lockDir}`);
-            }
-          }
-        }
-      }
-    }
-  } catch {
-    // Non-fatal — stranded lock directory check failed
-  }
-
-  // ── Stale parallel sessions ────────────────────────────────────────────
-  try {
-    const parallelStatuses = readAllSessionStatuses(basePath);
-    for (const status of parallelStatuses) {
-      if (isSessionStale(status)) {
-        issues.push({
-          severity: "warning",
-          code: "stale_parallel_session",
-          scope: "project",
-          unitId: status.milestoneId,
-          message: `Stale parallel session for ${status.milestoneId} (PID ${status.pid}, started ${new Date(status.startedAt).toISOString()}, last heartbeat ${new Date(status.lastHeartbeat).toISOString()}) — process is no longer running`,
-          file: `.gsd/parallel/${status.milestoneId}.status.json`,
-          fixable: true,
-        });
-
-        if (shouldFix("stale_parallel_session")) {
-          removeSessionStatus(basePath, status.milestoneId);
-          fixesApplied.push(`cleaned up stale parallel session for ${status.milestoneId}`);
-        }
-      }
-    }
-  } catch {
-    // Non-fatal — parallel session check failed
-  }
-
-  // ── Orphaned completed-units keys ─────────────────────────────────────
-  try {
-    const completedKeysFile = join(root, "completed-units.json");
-    if (existsSync(completedKeysFile)) {
-      const raw = readFileSync(completedKeysFile, "utf-8");
-      const keys: string[] = JSON.parse(raw);
-      const orphaned: string[] = [];
-
-      for (const key of keys) {
-        // Key format: "unitType/unitId" e.g. "execute-task/M001/S01/T01"
-        const slashIdx = key.indexOf("/");
-        if (slashIdx === -1) continue;
-        const unitType = key.slice(0, slashIdx);
-        const unitId = key.slice(slashIdx + 1);
-
-        // Only validate artifact-producing unit types
-        const { verifyExpectedArtifact } = await import("./auto-recovery.js");
-        if (!verifyExpectedArtifact(unitType, unitId, basePath)) {
-          orphaned.push(key);
-        }
-      }
-
-      if (orphaned.length > 0) {
-        issues.push({
-          severity: "warning",
-          code: "orphaned_completed_units",
-          scope: "project",
-          unitId: "project",
-          message: `${orphaned.length} completed-unit key(s) reference missing artifacts: ${orphaned.slice(0, 3).join(", ")}${orphaned.length > 3 ? "..." : ""}`,
-          file: ".gsd/completed-units.json",
-          fixable: true,
-        });
-
-        if (shouldFix("orphaned_completed_units")) {
-          const orphanedSet = new Set(orphaned);
-          const remaining = keys.filter((key) => !orphanedSet.has(key));
-          await saveFile(completedKeysFile, JSON.stringify(remaining));
-          fixesApplied.push(`removed ${orphaned.length} orphaned completed-unit key(s)`);
-        }
-      }
-    }
-  } catch {
-    // Non-fatal — completed-units check failed
-  }
-
-  // ── Stale hook state ──────────────────────────────────────────────────
-  try {
-    const hookStateFile = join(root, "hook-state.json");
-    if (existsSync(hookStateFile)) {
-      const raw = readFileSync(hookStateFile, "utf-8");
-      const state = JSON.parse(raw);
-      const hasCycleCounts = state.cycleCounts && typeof state.cycleCounts === "object"
-        && Object.keys(state.cycleCounts).length > 0;
-
-      // Only flag if there are actual cycle counts AND no auto-mode is running
-      if (hasCycleCounts) {
-        const lock = readCrashLock(basePath);
-        const autoRunning = lock ? isLockProcessAlive(lock) : false;
-
-        if (!autoRunning) {
-          issues.push({
-            severity: "info",
-            code: "stale_hook_state",
-            scope: "project",
-            unitId: "project",
-            message: `hook-state.json has ${Object.keys(state.cycleCounts).length} residual cycle count(s) from a previous session`,
-            file: ".gsd/hook-state.json",
-            fixable: true,
-          });
-
-          if (shouldFix("stale_hook_state")) {
-            const { clearPersistedHookState } = await import("./post-unit-hooks.js");
-            clearPersistedHookState(basePath);
-            fixesApplied.push("cleared stale hook-state.json");
-          }
-        }
-      }
-    }
-  } catch {
-    // Non-fatal — hook state check failed
-  }
-
-  // ── Activity log bloat ────────────────────────────────────────────────
-  try {
-    const activityDir = join(root, "activity");
-    if (existsSync(activityDir)) {
-      const files = readdirSync(activityDir);
-      let totalSize = 0;
-      for (const f of files) {
-        try {
-          totalSize += statSync(join(activityDir, f)).size;
-        } catch {
-          // stat failed — skip
-        }
-      }
-
-      const totalMB = totalSize / (1024 * 1024);
-      const BLOAT_FILE_THRESHOLD = 500;
-      const BLOAT_SIZE_MB = 100;
-
-      if (files.length > BLOAT_FILE_THRESHOLD || totalMB > BLOAT_SIZE_MB) {
-        issues.push({
-          severity: "warning",
-          code: "activity_log_bloat",
-          scope: "project",
-          unitId: "project",
-          message: `Activity logs: ${files.length} files, ${totalMB.toFixed(1)}MB (thresholds: ${BLOAT_FILE_THRESHOLD} files / ${BLOAT_SIZE_MB}MB)`,
-          file: ".gsd/activity/",
-          fixable: true,
-        });
-
-        if (shouldFix("activity_log_bloat")) {
-          const { pruneActivityLogs } = await import("./activity-log.js");
-          pruneActivityLogs(activityDir, 7); // 7-day retention
-          fixesApplied.push("pruned activity logs (7-day retention)");
-        }
-      }
-    }
-  } catch {
-    // Non-fatal — activity log check failed
-  }
-
-  // ── STATE.md health ───────────────────────────────────────────────────
-  try {
-    const stateFilePath = resolveGsdRootFile(basePath, "STATE");
-    const milestonesPath = milestonesDir(basePath);
-
-    if (existsSync(milestonesPath)) {
-      if (!existsSync(stateFilePath)) {
-        issues.push({
-          severity: "warning",
-          code: "state_file_missing",
-          scope: "project",
-          unitId: "project",
-          message: "STATE.md is missing — state display will not work",
-          file: ".gsd/STATE.md",
-          fixable: true,
-        });
-
-        if (shouldFix("state_file_missing")) {
-          const state = await deriveState(basePath);
-          await saveFile(stateFilePath, buildStateMarkdownForCheck(state));
-          fixesApplied.push("created STATE.md from derived state");
-        }
-      } else {
-        // Check if STATE.md is stale by comparing active milestone/slice/phase
-        const currentContent = readFileSync(stateFilePath, "utf-8");
-        const state = await deriveState(basePath);
-        const freshContent = buildStateMarkdownForCheck(state);
-
-        // Extract key fields for comparison — don't compare full content
-        // since timestamp/formatting differences are normal
-        const extractFields = (content: string) => {
-          const milestone = content.match(/\*\*Active Milestone:\*\*\s*(.+)/)?.[1]?.trim() ?? "";
-          const slice = content.match(/\*\*Active Slice:\*\*\s*(.+)/)?.[1]?.trim() ?? "";
-          const phase = content.match(/\*\*Phase:\*\*\s*(.+)/)?.[1]?.trim() ?? "";
-          return { milestone, slice, phase };
-        };
-
-        const current = extractFields(currentContent);
-        const fresh = extractFields(freshContent);
-
-        if (current.milestone !== fresh.milestone || current.slice !== fresh.slice || current.phase !== fresh.phase) {
-          issues.push({
-            severity: "warning",
-            code: "state_file_stale",
-            scope: "project",
-            unitId: "project",
-            message: `STATE.md is stale — shows "${current.phase}" but derived state is "${fresh.phase}"`,
-            file: ".gsd/STATE.md",
-            fixable: true,
-          });
-
-          if (shouldFix("state_file_stale")) {
-            await saveFile(stateFilePath, freshContent);
-            fixesApplied.push("rebuilt STATE.md from derived state");
-          }
-        }
-      }
-    }
-  } catch {
-    // Non-fatal — STATE.md check failed
-  }
-
-  // ── Gitignore drift ───────────────────────────────────────────────────
-  try {
-    const gitignorePath = join(basePath, ".gitignore");
-    if (existsSync(gitignorePath) && nativeIsRepo(basePath)) {
-      const content = readFileSync(gitignorePath, "utf-8");
-      const existingLines = new Set(
-        content.split("\n").map(l => l.trim()).filter(l => l && !l.startsWith("#")),
-      );
-
-      // Check for critical runtime patterns that must be present
-      const criticalPatterns = [
-        ".gsd/activity/",
-        ".gsd/runtime/",
-        ".gsd/auto.lock",
-        ".gsd/gsd.db",
-        ".gsd/completed-units.json",
-      ];
-
-      // If blanket .gsd/ or .gsd is present, all patterns are covered
-      const hasBlanketIgnore = existingLines.has(".gsd/") || existingLines.has(".gsd");
-
-      if (!hasBlanketIgnore) {
-        const missing = criticalPatterns.filter(p => !existingLines.has(p));
-        if (missing.length > 0) {
-          issues.push({
-            severity: "warning",
-            code: "gitignore_missing_patterns",
-            scope: "project",
-            unitId: "project",
-            message: `${missing.length} critical GSD runtime pattern(s) missing from .gitignore: ${missing.join(", ")}`,
-            file: ".gitignore",
-            fixable: true,
-          });
-
-          if (shouldFix("gitignore_missing_patterns")) {
-            ensureGitignore(basePath);
-            fixesApplied.push("added missing GSD runtime patterns to .gitignore");
-          }
-        }
-      }
-    }
-  } catch {
-    // Non-fatal — gitignore check failed
-  }
-
-  // ── External state symlink health ──────────────────────────────────────
-  try {
-    const localGsd = join(basePath, ".gsd");
-    if (existsSync(localGsd)) {
-      const stat = lstatSync(localGsd);
-
-      // Check for .gsd.migrating (failed migration)
-      const migratingPath = join(basePath, ".gsd.migrating");
-      if (existsSync(migratingPath)) {
-        issues.push({
-          severity: "error",
-          code: "failed_migration",
-          scope: "project",
-          unitId: "project",
-          message: "Found .gsd.migrating — a previous external state migration failed. State may be incomplete.",
-          file: ".gsd.migrating",
-          fixable: true,
-        });
-
-        if (shouldFix("failed_migration")) {
-          if (recoverFailedMigration(basePath)) {
-            fixesApplied.push("recovered failed migration (.gsd.migrating → .gsd)");
-          }
-        }
-      }
-
-      // Check symlink target exists
-      if (stat.isSymbolicLink()) {
-        try {
-          realpathSync(localGsd);
-        } catch {
-          issues.push({
-            severity: "error",
-            code: "broken_symlink",
-            scope: "project",
-            unitId: "project",
-            message: ".gsd symlink target does not exist. External state directory may have been deleted.",
-            file: ".gsd",
-            fixable: false,
-          });
-        }
-      }
-    }
-  } catch {
-    // Non-fatal — external state check failed
-  }
-
-  // ── Numbered .gsd collision variants (#2205) ───────────────────────────
-  // macOS APFS can create ".gsd 2", ".gsd 3" etc. when a directory blocks
-  // symlink creation. These must be removed so the canonical .gsd is used.
-  try {
-    const variantPattern = /^\.gsd \d+$/;
-    const entries = readdirSync(basePath);
-    const variants = entries.filter(e => variantPattern.test(e));
-    if (variants.length > 0) {
-      for (const v of variants) {
-        issues.push({
-          severity: "warning",
-          code: "numbered_gsd_variant",
-          scope: "project",
-          unitId: "project",
-          message: `Found macOS collision variant "${v}" — this can cause GSD state to appear deleted.`,
-          file: v,
-          fixable: true,
-        });
-      }
-
-      if (shouldFix("numbered_gsd_variant")) {
-        const removed = cleanNumberedGsdVariants(basePath);
-        for (const name of removed) {
-          fixesApplied.push(`removed numbered .gsd variant: ${name}`);
-        }
-      }
-    }
-  } catch {
-    // Non-fatal — variant check failed
-  }
-
-  // ── Metrics ledger integrity ───────────────────────────────────────────
-  try {
-    const metricsPath = join(root, "metrics.json");
-    if (existsSync(metricsPath)) {
-      try {
-        const raw = readFileSync(metricsPath, "utf-8");
-        const ledger = JSON.parse(raw);
-        if (ledger.version !== 1 || !Array.isArray(ledger.units)) {
-          issues.push({
-            severity: "warning",
-            code: "metrics_ledger_corrupt",
-            scope: "project",
-            unitId: "project",
-            message: "metrics.json has an unexpected structure (version !== 1 or units is not an array) — metrics data may be unreliable",
-            file: ".gsd/metrics.json",
-            fixable: false,
-          });
-        }
-      } catch {
-        issues.push({
-          severity: "warning",
-          code: "metrics_ledger_corrupt",
-          scope: "project",
-          unitId: "project",
-          message: "metrics.json is not valid JSON — metrics data may be corrupt",
-          file: ".gsd/metrics.json",
-          fixable: false,
-        });
-      }
-    }
-  } catch {
-    // Non-fatal — metrics check failed
-  }
-
-  // ── Metrics ledger bloat ──────────────────────────────────────────────
-  // The metrics ledger has no TTL and grows by one entry per completed unit.
-  // At 50 units/day a project can accumulate tens of thousands of entries over
-  // months of use. Prune to the newest 1500 when the threshold is exceeded.
-  try {
-    const metricsFilePath = join(root, "metrics.json");
-    if (existsSync(metricsFilePath)) {
-      try {
-        const raw = readFileSync(metricsFilePath, "utf-8");
-        const parsed = JSON.parse(raw);
-        const BLOAT_UNITS_THRESHOLD = 2000;
-        if (parsed.version === 1 && Array.isArray(parsed.units) && parsed.units.length > BLOAT_UNITS_THRESHOLD) {
-          const fileSizeMB = (statSync(metricsFilePath).size / (1024 * 1024)).toFixed(1);
-          issues.push({
-            severity: "warning",
-            code: "metrics_ledger_bloat",
-            scope: "project",
-            unitId: "project",
-            message: `metrics.json has ${parsed.units.length} unit entries (${fileSizeMB}MB) — threshold is ${BLOAT_UNITS_THRESHOLD}. Run /gsd doctor --fix to prune to the newest 1500 entries.`,
-            file: ".gsd/metrics.json",
-            fixable: true,
-          });
-          if (shouldFix("metrics_ledger_bloat")) {
-            const { pruneMetricsLedger } = await import("./metrics.js");
-            const removed = pruneMetricsLedger(basePath, 1500);
-            fixesApplied.push(`pruned metrics ledger: removed ${removed} oldest entries (${parsed.units.length - removed} remain)`);
-          }
-        }
-      } catch {
-        // JSON parse failed — already handled by the integrity check above
-      }
-    }
-  } catch {
-    // Non-fatal — metrics bloat check failed
-  }
-
-  // ── Large planning file detection ──────────────────────────────────────
-  // Files over 100KB can cause LLM context pressure. Report the worst offenders.
-  try {
-    const MAX_FILE_BYTES = 100 * 1024; // 100KB
-    const milestonesPath = milestonesDir(basePath);
-    if (existsSync(milestonesPath)) {
-      const largeFiles: Array<{ path: string; sizeKB: number }> = [];
-      function scanForLargeFiles(dir: string, depth = 0): void {
-        if (depth > 6) return;
-        try {
-          for (const entry of readdirSync(dir)) {
-            const full = join(dir, entry);
-            try {
-              const s = statSync(full);
-              if (s.isDirectory()) { scanForLargeFiles(full, depth + 1); continue; }
-              if (entry.endsWith(".md") && s.size > MAX_FILE_BYTES) {
-                largeFiles.push({ path: full.replace(basePath + "/", ""), sizeKB: Math.round(s.size / 1024) });
-              }
-            } catch { /* skip entry */ }
-          }
-        } catch { /* skip dir */ }
-      }
-      scanForLargeFiles(milestonesPath);
-      if (largeFiles.length > 0) {
-        largeFiles.sort((a, b) => b.sizeKB - a.sizeKB);
-        const worst = largeFiles[0]!;
-        issues.push({
-          severity: "warning",
-          code: "large_planning_file",
-          scope: "project",
-          unitId: "project",
-          message: `${largeFiles.length} planning file(s) exceed 100KB — largest: ${worst.path} (${worst.sizeKB}KB). Large files cause LLM context pressure.`,
-          file: worst.path,
-          fixable: false,
-        });
-      }
-    }
-  } catch {
-    // Non-fatal — large file scan failed
-  }
-
-  // ── Snapshot ref bloat ────────────────────────────────────────────────
-  // refs/gsd/snapshots/ accumulate over time. Prune to newest 5 per label
-  // when total count exceeds threshold.
-  try {
-    if (nativeIsRepo(basePath)) {
-      const refs = nativeForEachRef(basePath, "refs/gsd/snapshots/");
-      if (refs.length > 50) {
-        issues.push({
-          severity: "warning",
-          code: "snapshot_ref_bloat",
-          scope: "project",
-          unitId: "project",
-          message: `${refs.length} snapshot refs found under refs/gsd/snapshots/ — pruning to newest 5 per label will reclaim git storage`,
-          fixable: true,
-        });
-
-        if (shouldFix("snapshot_ref_bloat")) {
-          const byLabel = new Map<string, string[]>();
-          for (const ref of refs) {
-            const parts = ref.split("/");
-            const label = parts.slice(0, -1).join("/");
-            if (!byLabel.has(label)) byLabel.set(label, []);
-            byLabel.get(label)!.push(ref);
-          }
-          let pruned = 0;
-          for (const [, labelRefs] of byLabel) {
-            const sorted = labelRefs.sort();
-            for (const old of sorted.slice(0, -5)) {
-              try {
-                nativeUpdateRef(basePath, old);
-                pruned++;
-              } catch { /* skip */ }
-            }
-          }
-          if (pruned > 0) {
-            fixesApplied.push(`pruned ${pruned} old snapshot ref(s)`);
-          }
-        }
-      }
-    }
-  } catch {
-    // Non-fatal — snapshot ref check failed
-  }
-}
-
-/**
- * Build STATE.md markdown content from derived state.
- * Local helper used by checkRuntimeHealth for STATE.md drift detection and repair.
- */
-function buildStateMarkdownForCheck(state: Awaited<ReturnType<typeof deriveState>>): string {
-  const lines: string[] = [];
-  lines.push("# GSD State", "");
-
-  const activeMilestone = state.activeMilestone
-    ? `${state.activeMilestone.id}: ${state.activeMilestone.title}`
-    : "None";
-  const activeSlice = state.activeSlice
-    ? `${state.activeSlice.id}: ${state.activeSlice.title}`
-    : "None";
-
-  lines.push(`**Active Milestone:** ${activeMilestone}`);
-  lines.push(`**Active Slice:** ${activeSlice}`);
-  lines.push(`**Phase:** ${state.phase}`);
-  if (state.requirements) {
-    lines.push(`**Requirements Status:** ${state.requirements.active} active · ${state.requirements.validated} validated · ${state.requirements.deferred} deferred · ${state.requirements.outOfScope} out of scope`);
-  }
-  lines.push("");
-  lines.push("## Milestone Registry");
-
-  for (const entry of state.registry) {
-    const glyph = entry.status === "complete" ? "\u2705" : entry.status === "active" ? "\uD83D\uDD04" : entry.status === "parked" ? "\u23F8\uFE0F" : "\u2B1C";
-    lines.push(`- ${glyph} **${entry.id}:** ${entry.title}`);
-  }
-
-  lines.push("");
-  lines.push("## Recent Decisions");
-  if (state.recentDecisions.length > 0) {
-    for (const decision of state.recentDecisions) lines.push(`- ${decision}`);
-  } else {
-    lines.push("- None recorded");
-  }
-
-  lines.push("");
-  lines.push("## Blockers");
-  if (state.blockers.length > 0) {
-    for (const blocker of state.blockers) lines.push(`- ${blocker}`);
-  } else {
-    lines.push("- None");
-  }
-
-  lines.push("");
-  lines.push("## Next Action");
-  lines.push(state.nextAction || "None");
-  lines.push("");
-
-  return lines.join("\n");
-}
-
-// ── Global Health Checks ────────────────────────────────────────────────────
-// Cross-project checks that scan ~/.gsd/ rather than a specific project directory.
-
-/**
- * Check for orphaned project state directories in ~/.gsd/projects/.
- *
- * A project directory is orphaned when its recorded gitRoot no longer exists
- * on disk — the repo was deleted, moved, or the external drive was unmounted.
- * These directories accumulate silently and waste disk space.
- *
- * Severity: info — orphaned state is harmless but takes disk space.
- * Fixable: yes — rmSync the directory. Never auto-fixed at fixLevel="task".
- */
-export async function checkGlobalHealth(
-  issues: DoctorIssue[],
-  fixesApplied: string[],
-  shouldFix: (code: DoctorIssueCode) => boolean,
-): Promise<void> {
-  try {
-    const projectsDir = externalProjectsRoot();
-
-    if (!existsSync(projectsDir)) return;
-
-    let entries: string[];
-    try {
-      entries = readdirSync(projectsDir, { withFileTypes: true })
-        .filter(e => e.isDirectory())
-        .map(e => e.name);
-    } catch {
-      return; // Can't read directory — skip
-    }
-
-    if (entries.length === 0) return;
-
-    const orphaned: Array<{ hash: string; gitRoot: string; remoteUrl: string }> = [];
-    let unknownCount = 0;
-
-    for (const hash of entries) {
-      const dirPath = join(projectsDir, hash);
-      const meta = readRepoMeta(dirPath);
-      if (!meta) {
-        unknownCount++;
-        continue;
-      }
-      if (!existsSync(meta.gitRoot)) {
-        orphaned.push({ hash, gitRoot: meta.gitRoot, remoteUrl: meta.remoteUrl });
-      }
-    }
-
-    if (orphaned.length === 0) return;
-
-    const labels = orphaned.slice(0, 3).map(o => o.gitRoot).join(", ");
-    const overflow = orphaned.length > 3 ? ` (+${orphaned.length - 3} more)` : "";
-    const unknownNote = unknownCount > 0 ? ` — ${unknownCount} additional director${unknownCount === 1 ? "y" : "ies"} have no metadata yet (open those repos once to register them)` : "";
-
-    issues.push({
-      severity: "info",
-      code: "orphaned_project_state",
-      scope: "project",
-      unitId: "global",
-      message: `${orphaned.length} orphaned GSD project state director${orphaned.length === 1 ? "y" : "ies"} in ${projectsDir} whose git root no longer exists: ${labels}${overflow}${unknownNote}. Run /gsd cleanup projects to audit or /gsd cleanup projects --fix to reclaim disk space.`,
-      file: projectsDir,
-      fixable: true,
-    });
-
-    if (shouldFix("orphaned_project_state")) {
-      let removed = 0;
-      for (const { hash } of orphaned) {
-        try {
-          rmSync(join(projectsDir, hash), { recursive: true, force: true });
-          removed++;
-        } catch {
-          // Individual removal failure is non-fatal — continue with remaining
-        }
-      }
-      fixesApplied.push(`removed ${removed} orphaned project state director${removed === 1 ? "y" : "ies"} from ${projectsDir}`);
-    }
-  } catch {
-    // Non-fatal — global health check must not block per-project doctor
-  }
-}
-
-// ── Engine Health Checks ────────────────────────────────────────────────────
-// DB constraint violation detection and projection drift checks.
-
-export async function checkEngineHealth(
-  basePath: string,
-  issues: DoctorIssue[],
-  fixesApplied: string[],
-): Promise<void> {
-  // ── DB constraint violation detection (full doctor only, not pre-dispatch per D-10) ──
-  try {
-    if (isDbAvailable()) {
-      const adapter = _getAdapter()!;
-
-      // a. Orphaned tasks (task.slice_id points to non-existent slice)
-      try {
-        const orphanedTasks = adapter
-          .prepare(
-            `SELECT t.id, t.slice_id, t.milestone_id
-             FROM tasks t
-             LEFT JOIN slices s ON t.milestone_id = s.milestone_id AND t.slice_id = s.id
-             WHERE s.id IS NULL`,
-          )
-          .all() as Array<{ id: string; slice_id: string; milestone_id: string }>;
-
-        for (const row of orphanedTasks) {
-          issues.push({
-            severity: "error",
-            code: "db_orphaned_task",
-            scope: "task",
-            unitId: `${row.milestone_id}/${row.slice_id}/${row.id}`,
-            message: `Task ${row.id} references slice ${row.slice_id} in milestone ${row.milestone_id} but no such slice exists in the database`,
-            fixable: false,
-          });
-        }
-      } catch {
-        // Non-fatal — orphaned task check failed
-      }
-
-      // b. Orphaned slices (slice.milestone_id points to non-existent milestone)
-      try {
-        const orphanedSlices = adapter
-          .prepare(
-            `SELECT s.id, s.milestone_id
-             FROM slices s
-             LEFT JOIN milestones m ON s.milestone_id = m.id
-             WHERE m.id IS NULL`,
-          )
-          .all() as Array<{ id: string; milestone_id: string }>;
-
-        for (const row of orphanedSlices) {
-          issues.push({
-            severity: "error",
-            code: "db_orphaned_slice",
-            scope: "slice",
-            unitId: `${row.milestone_id}/${row.id}`,
-            message: `Slice ${row.id} references milestone ${row.milestone_id} but no such milestone exists in the database`,
-            fixable: false,
-          });
-        }
-      } catch {
-        // Non-fatal — orphaned slice check failed
-      }
-
-      // c. Tasks marked complete without summaries
-      try {
-        const doneTasks = adapter
-          .prepare(
-            `SELECT id, slice_id, milestone_id FROM tasks
-             WHERE status = 'done' AND (summary IS NULL OR summary = '')`,
-          )
-          .all() as Array<{ id: string; slice_id: string; milestone_id: string }>;
-
-        for (const row of doneTasks) {
-          issues.push({
-            severity: "warning",
-            code: "db_done_task_no_summary",
-            scope: "task",
-            unitId: `${row.milestone_id}/${row.slice_id}/${row.id}`,
-            message: `Task ${row.id} is marked done but has no summary in the database`,
-            fixable: false,
-          });
-        }
-      } catch {
-        // Non-fatal — done-task-no-summary check failed
-      }
-
-      // d. Duplicate entity IDs (safety check)
-      try {
-        const dupMilestones = adapter
-          .prepare("SELECT id, COUNT(*) as cnt FROM milestones GROUP BY id HAVING cnt > 1")
-          .all() as Array<{ id: string; cnt: number }>;
-        for (const row of dupMilestones) {
-          issues.push({
-            severity: "error",
-            code: "db_duplicate_id",
-            scope: "milestone",
-            unitId: row.id,
-            message: `Duplicate milestone ID "${row.id}" appears ${row.cnt} times in the database`,
-            fixable: false,
-          });
-        }
-
-        const dupSlices = adapter
-          .prepare("SELECT id, milestone_id, COUNT(*) as cnt FROM slices GROUP BY id, milestone_id HAVING cnt > 1")
-          .all() as Array<{ id: string; milestone_id: string; cnt: number }>;
-        for (const row of dupSlices) {
-          issues.push({
-            severity: "error",
-            code: "db_duplicate_id",
-            scope: "slice",
-            unitId: `${row.milestone_id}/${row.id}`,
-            message: `Duplicate slice ID "${row.id}" in milestone ${row.milestone_id} appears ${row.cnt} times`,
-            fixable: false,
-          });
-        }
-
-        const dupTasks = adapter
-          .prepare("SELECT id, slice_id, milestone_id, COUNT(*) as cnt FROM tasks GROUP BY id, slice_id, milestone_id HAVING cnt > 1")
-          .all() as Array<{ id: string; slice_id: string; milestone_id: string; cnt: number }>;
-        for (const row of dupTasks) {
-          issues.push({
-            severity: "error",
-            code: "db_duplicate_id",
-            scope: "task",
-            unitId: `${row.milestone_id}/${row.slice_id}/${row.id}`,
-            message: `Duplicate task ID "${row.id}" in slice ${row.slice_id} appears ${row.cnt} times`,
-            fixable: false,
-          });
-        }
-      } catch {
-        // Non-fatal — duplicate ID check failed
-      }
-    }
-  } catch {
-    // Non-fatal — DB constraint checks failed entirely
-  }
-
-  // ── Projection drift detection ──────────────────────────────────────────
-  // If the DB is available, check whether markdown projections are stale
-  // relative to the event log and re-render them.
-  try {
-    if (isDbAvailable()) {
-      const eventLogPath = join(basePath, ".gsd", "event-log.jsonl");
-      const events = readEvents(eventLogPath);
-      if (events.length > 0) {
-        const lastEventTs = new Date(events[events.length - 1]!.ts).getTime();
-        const state = await deriveState(basePath);
-        for (const milestone of state.registry) {
-          if (milestone.status === "complete") continue;
-          const roadmapPath = resolveMilestoneFile(basePath, milestone.id, "ROADMAP");
-          if (!roadmapPath || !existsSync(roadmapPath)) {
-            try {
-              await renderAllProjections(basePath, milestone.id);
-              fixesApplied.push(`re-rendered missing projections for ${milestone.id}`);
-            } catch {
-              // Non-fatal — projection re-render failed
-            }
-            continue;
-          }
-          const projectionMtime = statSync(roadmapPath).mtimeMs;
-          if (lastEventTs > projectionMtime) {
-            try {
-              await renderAllProjections(basePath, milestone.id);
-              fixesApplied.push(`re-rendered stale projections for ${milestone.id}`);
-            } catch {
-              // Non-fatal — projection re-render failed
-            }
-          }
-        }
-      }
-    }
-  } catch {
-    // Non-fatal — projection drift check must never block doctor
-  }
-}
+// Re-exports for backward compatibility
+export { checkGitHealth } from "./doctor-git-checks.js";
+export { checkRuntimeHealth } from "./doctor-runtime-checks.js";
+export { checkGlobalHealth } from "./doctor-global-checks.js";
+export { checkEngineHealth } from "./doctor-engine-checks.js";
diff --git a/src/resources/extensions/gsd/doctor-engine-checks.ts b/src/resources/extensions/gsd/doctor-engine-checks.ts
new file mode 100644
index 000000000..8b74dcac4
--- /dev/null
+++ b/src/resources/extensions/gsd/doctor-engine-checks.ts
@@ -0,0 +1,182 @@
+import { existsSync, statSync } from "node:fs";
+import { join } from "node:path";
+
+import type { DoctorIssue } from "./doctor-types.js";
+import { isDbAvailable, _getAdapter } from "./gsd-db.js";
+import { resolveMilestoneFile } from "./paths.js";
+import { deriveState } from "./state.js";
+import { readEvents } from "./workflow-events.js";
+import { renderAllProjections } from "./workflow-projections.js";
+
+export async function checkEngineHealth(
+  basePath: string,
+  issues: DoctorIssue[],
+  fixesApplied: string[],
+): Promise<void> {
+  // ── DB constraint violation detection (full doctor only, not pre-dispatch per D-10) ──
+  try {
+    if (isDbAvailable()) {
+      const adapter = _getAdapter()!;
+
+      // a. Orphaned tasks (task.slice_id points to non-existent slice)
+      try {
+        const orphanedTasks = adapter
+          .prepare(
+            `SELECT t.id, t.slice_id, t.milestone_id
+             FROM tasks t
+             LEFT JOIN slices s ON t.milestone_id = s.milestone_id AND t.slice_id = s.id
+             WHERE s.id IS NULL`,
+          )
+          .all() as Array<{ id: string; slice_id: string; milestone_id: string }>;
+
+        for (const row of orphanedTasks) {
+          issues.push({
+            severity: "error",
+            code: "db_orphaned_task",
+            scope: "task",
+            unitId: `${row.milestone_id}/${row.slice_id}/${row.id}`,
+            message: `Task ${row.id} references slice ${row.slice_id} in milestone ${row.milestone_id} but no such slice exists in the database`,
+            fixable: false,
+          });
+        }
+      } catch {
+        // Non-fatal — orphaned task check failed
+      }
+
+      // b. Orphaned slices (slice.milestone_id points to non-existent milestone)
+      try {
+        const orphanedSlices = adapter
+          .prepare(
+            `SELECT s.id, s.milestone_id
+             FROM slices s
+             LEFT JOIN milestones m ON s.milestone_id = m.id
+             WHERE m.id IS NULL`,
+          )
+          .all() as Array<{ id: string; milestone_id: string }>;
+
+        for (const row of orphanedSlices) {
+          issues.push({
+            severity: "error",
+            code: "db_orphaned_slice",
+            scope: "slice",
+            unitId: `${row.milestone_id}/${row.id}`,
+            message: `Slice ${row.id} references milestone ${row.milestone_id} but no such milestone exists in the database`,
+            fixable: false,
+          });
+        }
+      } catch {
+        // Non-fatal — orphaned slice check failed
+      }
+
+      // c. Tasks marked complete without summaries
+      try {
+        const doneTasks = adapter
+          .prepare(
+            `SELECT id, slice_id, milestone_id FROM tasks
+             WHERE status = 'done' AND (summary IS NULL OR summary = '')`,
+          )
+          .all() as Array<{ id: string; slice_id: string; milestone_id: string }>;
+
+        for (const row of doneTasks) {
+          issues.push({
+            severity: "warning",
+            code: "db_done_task_no_summary",
+            scope: "task",
+            unitId: `${row.milestone_id}/${row.slice_id}/${row.id}`,
+            message: `Task ${row.id} is marked done but has no summary in the database`,
+            fixable: false,
+          });
+        }
+      } catch {
+        // Non-fatal — done-task-no-summary check failed
+      }
+
+      // d. Duplicate entity IDs (safety check)
+      try {
+        const dupMilestones = adapter
+          .prepare("SELECT id, COUNT(*) as cnt FROM milestones GROUP BY id HAVING cnt > 1")
+          .all() as Array<{ id: string; cnt: number }>;
+        for (const row of dupMilestones) {
+          issues.push({
+            severity: "error",
+            code: "db_duplicate_id",
+            scope: "milestone",
+            unitId: row.id,
+            message: `Duplicate milestone ID "${row.id}" appears ${row.cnt} times in the database`,
+            fixable: false,
+          });
+        }
+
+        const dupSlices = adapter
+          .prepare("SELECT id, milestone_id, COUNT(*) as cnt FROM slices GROUP BY id, milestone_id HAVING cnt > 1")
+          .all() as Array<{ id: string; milestone_id: string; cnt: number }>;
+        for (const row of dupSlices) {
+          issues.push({
+            severity: "error",
+            code: "db_duplicate_id",
+            scope: "slice",
+            unitId: `${row.milestone_id}/${row.id}`,
+            message: `Duplicate slice ID "${row.id}" in milestone ${row.milestone_id} appears ${row.cnt} times`,
+            fixable: false,
+          });
+        }
+
+        const dupTasks = adapter
+          .prepare("SELECT id, slice_id, milestone_id, COUNT(*) as cnt FROM tasks GROUP BY id, slice_id, milestone_id HAVING cnt > 1")
+          .all() as Array<{ id: string; slice_id: string; milestone_id: string; cnt: number }>;
+        for (const row of dupTasks) {
+          issues.push({
+            severity: "error",
+            code: "db_duplicate_id",
+            scope: "task",
+            unitId: `${row.milestone_id}/${row.slice_id}/${row.id}`,
+            message: `Duplicate task ID "${row.id}" in slice ${row.slice_id} appears ${row.cnt} times`,
+            fixable: false,
+          });
+        }
+      } catch {
+        // Non-fatal — duplicate ID check failed
+      }
+    }
+  } catch {
+    // Non-fatal — DB constraint checks failed entirely
+  }
+
+  // ── Projection drift detection ──────────────────────────────────────────
+  // If the DB is available, check whether markdown projections are stale
+  // relative to the event log and re-render them.
+  try {
+    if (isDbAvailable()) {
+      const eventLogPath = join(basePath, ".gsd", "event-log.jsonl");
+      const events = readEvents(eventLogPath);
+      if (events.length > 0) {
+        const lastEventTs = new Date(events[events.length - 1]!.ts).getTime();
+        const state = await deriveState(basePath);
+        for (const milestone of state.registry) {
+          if (milestone.status === "complete") continue;
+          const roadmapPath = resolveMilestoneFile(basePath, milestone.id, "ROADMAP");
+          if (!roadmapPath || !existsSync(roadmapPath)) {
+            try {
+              await renderAllProjections(basePath, milestone.id);
+              fixesApplied.push(`re-rendered missing projections for ${milestone.id}`);
+            } catch {
+              // Non-fatal — projection re-render failed
+            }
+            continue;
+          }
+          const projectionMtime = statSync(roadmapPath).mtimeMs;
+          if (lastEventTs > projectionMtime) {
+            try {
+              await renderAllProjections(basePath, milestone.id);
+              fixesApplied.push(`re-rendered stale projections for ${milestone.id}`);
+            } catch {
+              // Non-fatal — projection re-render failed
+            }
+          }
+        }
+      }
+    }
+  } catch {
+    // Non-fatal — projection drift check must never block doctor
+  }
+}
diff --git a/src/resources/extensions/gsd/doctor-git-checks.ts b/src/resources/extensions/gsd/doctor-git-checks.ts
new file mode 100644
index 000000000..0b8820108
--- /dev/null
+++ b/src/resources/extensions/gsd/doctor-git-checks.ts
@@ -0,0 +1,415 @@
+import { existsSync, readdirSync, realpathSync, rmSync, statSync } from "node:fs";
+import { join, sep } from "node:path";
+
+import type { DoctorIssue, DoctorIssueCode } from "./doctor-types.js";
+import { loadFile } from "./files.js";
+import { parseRoadmap as parseLegacyRoadmap } from "./parsers-legacy.js";
+import { isDbAvailable, getMilestoneSlices } from "./gsd-db.js";
+import { resolveMilestoneFile } from "./paths.js";
+import { deriveState, isMilestoneComplete } from "./state.js";
+import { listWorktrees, resolveGitDir, worktreesDir } from "./worktree-manager.js";
+import { abortAndReset } from "./git-self-heal.js";
+import { RUNTIME_EXCLUSION_PATHS, resolveMilestoneIntegrationBranch, writeIntegrationBranch } from "./git-service.js";
+import { nativeIsRepo, nativeWorktreeList, nativeWorktreeRemove, nativeBranchList, nativeBranchDelete, nativeLsFiles, nativeRmCached } from "./native-git-bridge.js";
+import { getAllWorktreeHealth } from "./worktree-health.js";
+import { loadEffectiveGSDPreferences } from "./preferences.js";
+
+export async function checkGitHealth(
+  basePath: string,
+  issues: DoctorIssue[],
+  fixesApplied: string[],
+  shouldFix: (code: DoctorIssueCode) => boolean,
+  isolationMode: "none" | "worktree" | "branch" = "none",
+): Promise<void> {
+  // Degrade gracefully if not a git repo
+  if (!nativeIsRepo(basePath)) {
+    return; // Not a git repo — skip all git health checks
+  }
+
+  const gitDir = resolveGitDir(basePath);
+
+  // ── Orphaned auto-worktrees & Stale milestone branches ────────────────
+  // These checks only apply in worktree/branch modes — skip in none mode
+  // where no milestone worktrees or branches are created.
+  if (isolationMode !== "none") {
+  try {
+    const worktrees = listWorktrees(basePath);
+    const milestoneWorktrees = worktrees.filter(wt => wt.branch.startsWith("milestone/"));
+
+    // Load roadmap state once for cross-referencing
+    const state = await deriveState(basePath);
+
+    for (const wt of milestoneWorktrees) {
+      // Extract milestone ID from branch name "milestone/M001" → "M001"
+      const milestoneId = wt.branch.replace(/^milestone\//, "");
+      const milestoneEntry = state.registry.find(m => m.id === milestoneId);
+
+      // Check if milestone is complete via roadmap
+      let isComplete = false;
+      if (milestoneEntry) {
+        if (isDbAvailable()) {
+          const dbSlices = getMilestoneSlices(milestoneId);
+          isComplete = dbSlices.length > 0 && dbSlices.every(s => s.status === "complete");
+        } else {
+          const roadmapPath = resolveMilestoneFile(basePath, milestoneId, "ROADMAP");
+          const roadmapContent = roadmapPath ? await loadFile(roadmapPath) : null;
+          if (roadmapContent) {
+            const roadmap = parseLegacyRoadmap(roadmapContent);
+            isComplete = isMilestoneComplete(roadmap);
+          }
+        }
+        // When DB unavailable and no roadmap, isComplete stays false
+      }
+
+      if (isComplete) {
+        issues.push({
+          severity: "warning",
+          code: "orphaned_auto_worktree",
+          scope: "milestone",
+          unitId: milestoneId,
+          message: `Worktree for completed milestone ${milestoneId} still exists at ${wt.path}`,
+          fixable: true,
+        });
+
+        if (shouldFix("orphaned_auto_worktree")) {
+          // If cwd is inside the worktree, chdir out first — matching the
+          // pattern in removeWorktree() (#1946). Without this, git cannot
+          // remove the worktree and the doctor enters a deadlock where it
+          // detects the orphan every run but never cleans it up.
+          const cwd = process.cwd();
+          if (wt.path === cwd || cwd.startsWith(wt.path + sep)) {
+            try {
+              process.chdir(basePath);
+            } catch {
+              fixesApplied.push(`skipped removing worktree at ${wt.path} (cannot chdir to basePath)`);
+              continue;
+            }
+          }
+          try {
+            nativeWorktreeRemove(basePath, wt.path, true);
+            fixesApplied.push(`removed orphaned worktree ${wt.path}`);
+          } catch {
+            fixesApplied.push(`failed to remove worktree ${wt.path}`);
+          }
+        }
+      }
+    }
+
+    // ── Stale milestone branches ─────────────────────────────────────────
+    try {
+      const branches = nativeBranchList(basePath, "milestone/*");
+      if (branches.length > 0) {
+        const worktreeBranches = new Set(milestoneWorktrees.map(wt => wt.branch));
+
+        for (const branch of branches) {
+          // Skip branches that have a worktree (handled above)
+          if (worktreeBranches.has(branch)) continue;
+
+          const milestoneId = branch.replace(/^milestone\//, "");
+          const roadmapPath = resolveMilestoneFile(basePath, milestoneId, "ROADMAP");
+          let branchMilestoneComplete = false;
+          if (isDbAvailable()) {
+            const dbSlices = getMilestoneSlices(milestoneId);
+            branchMilestoneComplete = dbSlices.length > 0 && dbSlices.every(s => s.status === "complete");
+          } else {
+            const roadmapContent = roadmapPath ? await loadFile(roadmapPath) : null;
+            if (!roadmapContent) continue;
+            const roadmap = parseLegacyRoadmap(roadmapContent);
+            branchMilestoneComplete = isMilestoneComplete(roadmap);
+          }
+          if (branchMilestoneComplete) {
+            issues.push({
+              severity: "info",
+              code: "stale_milestone_branch",
+              scope: "milestone",
+              unitId: milestoneId,
+              message: `Branch ${branch} exists for completed milestone ${milestoneId}`,
+              fixable: true,
+            });
+
+            if (shouldFix("stale_milestone_branch")) {
+              try {
+                nativeBranchDelete(basePath, branch, true);
+                fixesApplied.push(`deleted stale branch ${branch}`);
+              } catch {
+                fixesApplied.push(`failed to delete branch ${branch}`);
+              }
+            }
+          }
+        }
+      }
+    } catch {
+      // git branch list failed — skip stale branch check
+    }
+  } catch {
+    // listWorktrees or deriveState failed — skip worktree/branch checks
+  }
+  } // end isolationMode !== "none"
+
+  // ── Corrupt merge state ────────────────────────────────────────────────
+  try {
+    const mergeStateFiles = ["MERGE_HEAD", "SQUASH_MSG"];
+    const mergeStateDirs = ["rebase-apply", "rebase-merge"];
+    const found: string[] = [];
+
+    for (const f of mergeStateFiles) {
+      if (existsSync(join(gitDir, f))) found.push(f);
+    }
+    for (const d of mergeStateDirs) {
+      if (existsSync(join(gitDir, d))) found.push(d);
+    }
+
+    if (found.length > 0) {
+      issues.push({
+        severity: "error",
+        code: "corrupt_merge_state",
+        scope: "project",
+        unitId: "project",
+        message: `Corrupt merge/rebase state detected: ${found.join(", ")}`,
+        fixable: true,
+      });
+
+      if (shouldFix("corrupt_merge_state")) {
+        const result = abortAndReset(basePath);
+        fixesApplied.push(`cleaned merge state: ${result.cleaned.join(", ")}`);
+      }
+    }
+  } catch {
+    // Can't check .git dir — skip
+  }
+
+  // ── Tracked runtime files ──────────────────────────────────────────────
+  try {
+    const trackedPaths: string[] = [];
+    for (const exclusion of RUNTIME_EXCLUSION_PATHS) {
+      try {
+        const files = nativeLsFiles(basePath, exclusion);
+        if (files.length > 0) {
+          trackedPaths.push(...files);
+        }
+      } catch {
+        // Individual ls-files can fail — continue
+      }
+    }
+
+    if (trackedPaths.length > 0) {
+      issues.push({
+        severity: "warning",
+        code: "tracked_runtime_files",
+        scope: "project",
+        unitId: "project",
+        message: `${trackedPaths.length} runtime file(s) are tracked by git: ${trackedPaths.slice(0, 5).join(", ")}${trackedPaths.length > 5 ? "..." : ""}`,
+        fixable: true,
+      });
+
+      if (shouldFix("tracked_runtime_files")) {
+        try {
+          for (const exclusion of RUNTIME_EXCLUSION_PATHS) {
+            nativeRmCached(basePath, [exclusion]);
+          }
+          fixesApplied.push(`untracked ${trackedPaths.length} runtime file(s)`);
+        } catch {
+          fixesApplied.push("failed to untrack runtime files");
+        }
+      }
+    }
+  } catch {
+    // git ls-files failed — skip
+  }
+
+  // ── Legacy slice branches ──────────────────────────────────────────────
+  try {
+    const branchList = nativeBranchList(basePath, "gsd/*/*")
+      .filter((branch) => !branch.startsWith("gsd/quick/"));
+    if (branchList.length > 0) {
+      issues.push({
+        severity: "info",
+        code: "legacy_slice_branches",
+        scope: "project",
+        unitId: "project",
+        message: `${branchList.length} legacy slice branch(es) found: ${branchList.slice(0, 3).join(", ")}${branchList.length > 3 ? "..." : ""}. These are no longer used (branchless architecture).`,
+        fixable: true,
+      });
+
+      if (shouldFix("legacy_slice_branches")) {
+        let deleted = 0;
+        for (const branch of branchList) {
+          try {
+            nativeBranchDelete(basePath, branch, true);
+            deleted++;
+          } catch { /* skip branches that can't be deleted */ }
+        }
+        if (deleted > 0) {
+          fixesApplied.push(`deleted ${deleted} legacy slice branch(es)`);
+        }
+      }
+    }
+  } catch {
+    // git branch list failed — skip
+  }
+
+  // ── Integration branch existence ──────────────────────────────────────
+  // For each active (non-complete) milestone, verify the stored integration
+  // branch still exists in git. A missing integration branch blocks merge-back
+  // and causes the next merge operation to fail silently.
+  try {
+    const state = await deriveState(basePath);
+    const gitPrefs = loadEffectiveGSDPreferences()?.preferences?.git ?? {};
+    for (const milestone of state.registry) {
+      if (milestone.status === "complete") continue;
+      const resolution = resolveMilestoneIntegrationBranch(basePath, milestone.id, gitPrefs);
+      if (!resolution.recordedBranch) continue; // No stored branch — skip (not yet set)
+      if (resolution.status === "fallback" && resolution.effectiveBranch) {
+        issues.push({
+          severity: "warning",
+          code: "integration_branch_missing",
+          scope: "milestone",
+          unitId: milestone.id,
+          message: resolution.reason,
+          fixable: true,
+        });
+        if (shouldFix("integration_branch_missing")) {
+          writeIntegrationBranch(basePath, milestone.id, resolution.effectiveBranch);
+          fixesApplied.push(`updated integration branch for ${milestone.id} to "${resolution.effectiveBranch}"`);
+        }
+        continue;
+      }
+
+      if (resolution.status === "missing") {
+        issues.push({
+          severity: "error",
+          code: "integration_branch_missing",
+          scope: "milestone",
+          unitId: milestone.id,
+          message: resolution.reason,
+          fixable: false,
+        });
+      }
+    }
+  } catch {
+    // Non-fatal — integration branch check failed
+  }
+
+  // ── Orphaned worktree directories ────────────────────────────────────
+  // Worktree removal can fail after a branch delete, leaving a directory
+  // that is no longer registered with git. These orphaned dirs cause
+  // "already exists" errors when re-creating the same worktree name.
+  try {
+    const wtDir = worktreesDir(basePath);
+    if (existsSync(wtDir)) {
+      // Resolve symlinks and normalize separators so that symlinked .gsd
+      // paths (e.g. ~/.gsd/projects/<hash>/worktrees/…) match the paths
+      // returned by `git worktree list`.
+      const normalizePath = (p: string): string => {
+        try { p = realpathSync(p); } catch { /* path may not exist */ }
+        return p.replaceAll("\\", "/");
+      };
+      const registeredPaths = new Set(
+        nativeWorktreeList(basePath).map(entry => normalizePath(entry.path)),
+      );
+      for (const entry of readdirSync(wtDir)) {
+        const fullPath = join(wtDir, entry);
+        try {
+          if (!statSync(fullPath).isDirectory()) continue;
+        } catch { continue; }
+        const normalizedFullPath = normalizePath(fullPath);
+        if (!registeredPaths.has(normalizedFullPath)) {
+          issues.push({
+            severity: "warning",
+            code: "worktree_directory_orphaned",
+            scope: "project",
+            unitId: entry,
+            message: `Worktree directory ${fullPath} exists on disk but is not registered with git. Run "git worktree prune" or doctor --fix to remove it.`,
+            fixable: true,
+          });
+          if (shouldFix("worktree_directory_orphaned")) {
+            try {
+              rmSync(fullPath, { recursive: true, force: true });
+              fixesApplied.push(`removed orphaned worktree directory ${fullPath}`);
+            } catch {
+              fixesApplied.push(`failed to remove orphaned worktree directory ${fullPath}`);
+            }
+          }
+        }
+      }
+    }
+  } catch {
+    // Non-fatal — orphaned worktree directory check failed
+  }
+
+  // ── Worktree lifecycle checks ──────────────────────────────────────────
+  // Check GSD-managed worktrees for: merged branches, stale work, dirty
+  // state, and unpushed commits. Only worktrees under .gsd/worktrees/.
+  try {
+    const healthStatuses = getAllWorktreeHealth(basePath);
+    const cwd = process.cwd();
+
+    for (const health of healthStatuses) {
+      const wt = health.worktree;
+      const isCwd = wt.path === cwd || cwd.startsWith(wt.path + sep);
+
+      // Branch fully merged into main — safe to remove
+      if (health.mergedIntoMain) {
+        issues.push({
+          severity: "info",
+          code: "worktree_branch_merged",
+          scope: "project",
+          unitId: wt.name,
+          message: `Worktree "${wt.name}" (branch ${wt.branch}) is fully merged into main${health.safeToRemove ? " — safe to remove" : ""}`,
+          fixable: health.safeToRemove,
+        });
+
+        if (health.safeToRemove && shouldFix("worktree_branch_merged") && !isCwd) {
+          try {
+            const { removeWorktree } = await import("./worktree-manager.js");
+            removeWorktree(basePath, wt.name, { deleteBranch: true, branch: wt.branch });
+            fixesApplied.push(`removed merged worktree "${wt.name}" and deleted branch ${wt.branch}`);
+          } catch {
+            fixesApplied.push(`failed to remove merged worktree "${wt.name}"`);
+          }
+        }
+        // If merged, skip the stale/dirty/unpushed checks — they're irrelevant
+        continue;
+      }
+
+      // Stale: no commits in N days, not merged
+      if (health.stale) {
+        const days = Math.floor(health.lastCommitAgeDays);
+        issues.push({
+          severity: "warning",
+          code: "worktree_stale",
+          scope: "project",
+          unitId: wt.name,
+          message: `Worktree "${wt.name}" has had no commits in ${days} day${days === 1 ? "" : "s"}`,
+          fixable: false,
+        });
+      }
+
+      // Dirty: uncommitted changes in a worktree (only flag on stale worktrees to avoid noise)
+      if (health.dirty && health.stale) {
+        issues.push({
+          severity: "warning",
+          code: "worktree_dirty",
+          scope: "project",
+          unitId: wt.name,
+          message: `Worktree "${wt.name}" has ${health.dirtyFileCount} uncommitted file${health.dirtyFileCount === 1 ? "" : "s"} and is stale`,
+          fixable: false,
+        });
+      }
+
+      // Unpushed: commits not on any remote (only flag on stale worktrees to avoid noise)
+      if (health.unpushedCommits > 0 && health.stale) {
+        issues.push({
+          severity: "warning",
+          code: "worktree_unpushed",
+          scope: "project",
+          unitId: wt.name,
+          message: `Worktree "${wt.name}" has ${health.unpushedCommits} unpushed commit${health.unpushedCommits === 1 ? "" : "s"}`,
+          fixable: false,
+        });
+      }
+    }
+  } catch {
+    // Non-fatal — worktree lifecycle check failed
+  }
+}
diff --git a/src/resources/extensions/gsd/doctor-global-checks.ts b/src/resources/extensions/gsd/doctor-global-checks.ts
new file mode 100644
index 000000000..cc181910a
--- /dev/null
+++ b/src/resources/extensions/gsd/doctor-global-checks.ts
@@ -0,0 +1,84 @@
+import { existsSync, readdirSync, rmSync } from "node:fs";
+import { join } from "node:path";
+
+import type { DoctorIssue, DoctorIssueCode } from "./doctor-types.js";
+import { readRepoMeta, externalProjectsRoot } from "./repo-identity.js";
+
+/**
+ * Check for orphaned project state directories in ~/.gsd/projects/.
+ *
+ * A project directory is orphaned when its recorded gitRoot no longer exists
+ * on disk — the repo was deleted, moved, or the external drive was unmounted.
+ * These directories accumulate silently and waste disk space.
+ *
+ * Severity: info — orphaned state is harmless but takes disk space.
+ * Fixable: yes — rmSync the directory. Never auto-fixed at fixLevel="task".
+ */
+export async function checkGlobalHealth(
+  issues: DoctorIssue[],
+  fixesApplied: string[],
+  shouldFix: (code: DoctorIssueCode) => boolean,
+): Promise<void> {
+  try {
+    const projectsDir = externalProjectsRoot();
+
+    if (!existsSync(projectsDir)) return;
+
+    let entries: string[];
+    try {
+      entries = readdirSync(projectsDir, { withFileTypes: true })
+        .filter(e => e.isDirectory())
+        .map(e => e.name);
+    } catch {
+      return; // Can't read directory — skip
+    }
+
+    if (entries.length === 0) return;
+
+    const orphaned: Array<{ hash: string; gitRoot: string; remoteUrl: string }> = [];
+    let unknownCount = 0;
+
+    for (const hash of entries) {
+      const dirPath = join(projectsDir, hash);
+      const meta = readRepoMeta(dirPath);
+      if (!meta) {
+        unknownCount++;
+        continue;
+      }
+      if (!existsSync(meta.gitRoot)) {
+        orphaned.push({ hash, gitRoot: meta.gitRoot, remoteUrl: meta.remoteUrl });
+      }
+    }
+
+    if (orphaned.length === 0) return;
+
+    const labels = orphaned.slice(0, 3).map(o => o.gitRoot).join(", ");
+    const overflow = orphaned.length > 3 ? ` (+${orphaned.length - 3} more)` : "";
+    const unknownNote = unknownCount > 0 ? ` — ${unknownCount} additional director${unknownCount === 1 ? "y" : "ies"} have no metadata yet (open those repos once to register them)` : "";
+
+    issues.push({
+      severity: "info",
+      code: "orphaned_project_state",
+      scope: "project",
+      unitId: "global",
+      message: `${orphaned.length} orphaned GSD project state director${orphaned.length === 1 ? "y" : "ies"} in ${projectsDir} whose git root no longer exists: ${labels}${overflow}${unknownNote}. Run /gsd cleanup projects to audit or /gsd cleanup projects --fix to reclaim disk space.`,
+      file: projectsDir,
+      fixable: true,
+    });
+
+    if (shouldFix("orphaned_project_state")) {
+      let removed = 0;
+      for (const { hash } of orphaned) {
+        try {
+          rmSync(join(projectsDir, hash), { recursive: true, force: true });
+          removed++;
+        } catch {
+          // Individual removal failure is non-fatal — continue with remaining
+        }
+      }
+      fixesApplied.push(`removed ${removed} orphaned project state director${removed === 1 ? "y" : "ies"} from ${projectsDir}`);
+    }
+  } catch {
+    // Non-fatal — global health check must not block per-project doctor
+  }
+}
diff --git a/src/resources/extensions/gsd/doctor-runtime-checks.ts b/src/resources/extensions/gsd/doctor-runtime-checks.ts
new file mode 100644
index 000000000..1137981a7
--- /dev/null
+++ b/src/resources/extensions/gsd/doctor-runtime-checks.ts
@@ -0,0 +1,626 @@
+import { existsSync, lstatSync, readdirSync, readFileSync, realpathSync, rmSync, statSync } from "node:fs";
+import { basename, dirname, join } from "node:path";
+
+import type { DoctorIssue, DoctorIssueCode } from "./doctor-types.js";
+import { cleanNumberedGsdVariants } from "./repo-identity.js";
+import { milestonesDir, gsdRoot, resolveGsdRootFile } from "./paths.js";
+import { deriveState } from "./state.js";
+import { saveFile } from "./files.js";
+import { nativeIsRepo, nativeForEachRef, nativeUpdateRef } from "./native-git-bridge.js";
+import { readCrashLock, isLockProcessAlive, clearLock } from "./crash-recovery.js";
+import { ensureGitignore } from "./gitignore.js";
+import { readAllSessionStatuses, isSessionStale, removeSessionStatus } from "./session-status-io.js";
+import { recoverFailedMigration } from "./migrate-external.js";
+
+export async function checkRuntimeHealth(
+  basePath: string,
+  issues: DoctorIssue[],
+  fixesApplied: string[],
+  shouldFix: (code: DoctorIssueCode) => boolean,
+): Promise<void> {
+  const root = gsdRoot(basePath);
+
+  // ── Stale crash lock ──────────────────────────────────────────────────
+  try {
+    const lock = readCrashLock(basePath);
+    if (lock) {
+      const alive = isLockProcessAlive(lock);
+      if (!alive) {
+        issues.push({
+          severity: "error",
+          code: "stale_crash_lock",
+          scope: "project",
+          unitId: "project",
+          message: `Stale auto.lock from PID ${lock.pid} (started ${lock.startedAt}, was executing ${lock.unitType} ${lock.unitId}) — process is no longer running`,
+          file: ".gsd/auto.lock",
+          fixable: true,
+        });
+
+        if (shouldFix("stale_crash_lock")) {
+          clearLock(basePath);
+          fixesApplied.push("cleared stale auto.lock");
+        }
+      }
+    }
+  } catch {
+    // Non-fatal — crash lock check failed
+  }
+
+  // ── Stranded lock directory ────────────────────────────────────────────
+  // proper-lockfile creates a `.gsd.lock/` directory as the OS-level lock
+  // mechanism. If the process was SIGKILLed or crashed hard, this directory
+  // can remain on disk without any live process holding it. The next session
+  // fails to acquire the lock until the directory is removed (#1245).
+  try {
+    const lockDir = join(dirname(root), `${basename(root)}.lock`);
+    if (existsSync(lockDir)) {
+      const statRes = statSync(lockDir);
+      if (statRes.isDirectory()) {
+        // Check if any live process actually holds this lock
+        const lock = readCrashLock(basePath);
+        const lockHolderAlive = lock ? isLockProcessAlive(lock) : false;
+        if (!lockHolderAlive) {
+          issues.push({
+            severity: "error",
+            code: "stranded_lock_directory",
+            scope: "project",
+            unitId: "project",
+            message: `Stranded lock directory "${lockDir}" exists but no live process holds the session lock. This blocks new auto-mode sessions from starting.`,
+            file: lockDir,
+            fixable: true,
+          });
+          if (shouldFix("stranded_lock_directory")) {
+            try {
+              rmSync(lockDir, { recursive: true, force: true });
+              fixesApplied.push(`removed stranded lock directory ${lockDir}`);
+            } catch {
+              fixesApplied.push(`failed to remove stranded lock directory ${lockDir}`);
+            }
+          }
+        }
+      }
+    }
+  } catch {
+    // Non-fatal — stranded lock directory check failed
+  }
+
+  // ── Stale parallel sessions ────────────────────────────────────────────
+  try {
+    const parallelStatuses = readAllSessionStatuses(basePath);
+    for (const status of parallelStatuses) {
+      if (isSessionStale(status)) {
+        issues.push({
+          severity: "warning",
+          code: "stale_parallel_session",
+          scope: "project",
+          unitId: status.milestoneId,
+          message: `Stale parallel session for ${status.milestoneId} (PID ${status.pid}, started ${new Date(status.startedAt).toISOString()}, last heartbeat ${new Date(status.lastHeartbeat).toISOString()}) — process is no longer running`,
+          file: `.gsd/parallel/${status.milestoneId}.status.json`,
+          fixable: true,
+        });
+
+        if (shouldFix("stale_parallel_session")) {
+          removeSessionStatus(basePath, status.milestoneId);
+          fixesApplied.push(`cleaned up stale parallel session for ${status.milestoneId}`);
+        }
+      }
+    }
+  } catch {
+    // Non-fatal — parallel session check failed
+  }
+
+  // ── Orphaned completed-units keys ─────────────────────────────────────
+  try {
+    const completedKeysFile = join(root, "completed-units.json");
+    if (existsSync(completedKeysFile)) {
+      const raw = readFileSync(completedKeysFile, "utf-8");
+      const keys: string[] = JSON.parse(raw);
+      const orphaned: string[] = [];
+
+      for (const key of keys) {
+        // Key format: "unitType/unitId" e.g. "execute-task/M001/S01/T01"
+        const slashIdx = key.indexOf("/");
+        if (slashIdx === -1) continue;
+        const unitType = key.slice(0, slashIdx);
+        const unitId = key.slice(slashIdx + 1);
+
+        // Only validate artifact-producing unit types
+        const { verifyExpectedArtifact } = await import("./auto-recovery.js");
+        if (!verifyExpectedArtifact(unitType, unitId, basePath)) {
+          orphaned.push(key);
+        }
+      }
+
+      if (orphaned.length > 0) {
+        issues.push({
+          severity: "warning",
+          code: "orphaned_completed_units",
+          scope: "project",
+          unitId: "project",
+          message: `${orphaned.length} completed-unit key(s) reference missing artifacts: ${orphaned.slice(0, 3).join(", ")}${orphaned.length > 3 ? "..." : ""}`,
+          file: ".gsd/completed-units.json",
+          fixable: true,
+        });
+
+        if (shouldFix("orphaned_completed_units")) {
+          const orphanedSet = new Set(orphaned);
+          const remaining = keys.filter((key) => !orphanedSet.has(key));
+          await saveFile(completedKeysFile, JSON.stringify(remaining));
+          fixesApplied.push(`removed ${orphaned.length} orphaned completed-unit key(s)`);
+        }
+      }
+    }
+  } catch {
+    // Non-fatal — completed-units check failed
+  }
+
+  // ── Stale hook state ──────────────────────────────────────────────────
+  try {
+    const hookStateFile = join(root, "hook-state.json");
+    if (existsSync(hookStateFile)) {
+      const raw = readFileSync(hookStateFile, "utf-8");
+      const state = JSON.parse(raw);
+      const hasCycleCounts = state.cycleCounts && typeof state.cycleCounts === "object"
+        && Object.keys(state.cycleCounts).length > 0;
+
+      // Only flag if there are actual cycle counts AND no auto-mode is running
+      if (hasCycleCounts) {
+        const lock = readCrashLock(basePath);
+        const autoRunning = lock ? isLockProcessAlive(lock) : false;
+
+        if (!autoRunning) {
+          issues.push({
+            severity: "info",
+            code: "stale_hook_state",
+            scope: "project",
+            unitId: "project",
+            message: `hook-state.json has ${Object.keys(state.cycleCounts).length} residual cycle count(s) from a previous session`,
+            file: ".gsd/hook-state.json",
+            fixable: true,
+          });
+
+          if (shouldFix("stale_hook_state")) {
+            const { clearPersistedHookState } = await import("./post-unit-hooks.js");
+            clearPersistedHookState(basePath);
+            fixesApplied.push("cleared stale hook-state.json");
+          }
+        }
+      }
+    }
+  } catch {
+    // Non-fatal — hook state check failed
+  }
+
+  // ── Activity log bloat ────────────────────────────────────────────────
+  try {
+    const activityDir = join(root, "activity");
+    if (existsSync(activityDir)) {
+      const files = readdirSync(activityDir);
+      let totalSize = 0;
+      for (const f of files) {
+        try {
+          totalSize += statSync(join(activityDir, f)).size;
+        } catch {
+          // stat failed — skip
+        }
+      }
+
+      const totalMB = totalSize / (1024 * 1024);
+      const BLOAT_FILE_THRESHOLD = 500;
+      const BLOAT_SIZE_MB = 100;
+
+      if (files.length > BLOAT_FILE_THRESHOLD || totalMB > BLOAT_SIZE_MB) {
+        issues.push({
+          severity: "warning",
+          code: "activity_log_bloat",
+          scope: "project",
+          unitId: "project",
+          message: `Activity logs: ${files.length} files, ${totalMB.toFixed(1)}MB (thresholds: ${BLOAT_FILE_THRESHOLD} files / ${BLOAT_SIZE_MB}MB)`,
+          file: ".gsd/activity/",
+          fixable: true,
+        });
+
+        if (shouldFix("activity_log_bloat")) {
+          const { pruneActivityLogs } = await import("./activity-log.js");
+          pruneActivityLogs(activityDir, 7); // 7-day retention
+          fixesApplied.push("pruned activity logs (7-day retention)");
+        }
+      }
+    }
+  } catch {
+    // Non-fatal — activity log check failed
+  }
+
+  // ── STATE.md health ───────────────────────────────────────────────────
+  try {
+    const stateFilePath = resolveGsdRootFile(basePath, "STATE");
+    const milestonesPath = milestonesDir(basePath);
+
+    if (existsSync(milestonesPath)) {
+      if (!existsSync(stateFilePath)) {
+        issues.push({
+          severity: "warning",
+          code: "state_file_missing",
+          scope: "project",
+          unitId: "project",
+          message: "STATE.md is missing — state display will not work",
+          file: ".gsd/STATE.md",
+          fixable: true,
+        });
+
+        if (shouldFix("state_file_missing")) {
+          const state = await deriveState(basePath);
+          await saveFile(stateFilePath, buildStateMarkdownForCheck(state));
+          fixesApplied.push("created STATE.md from derived state");
+        }
+      } else {
+        // Check if STATE.md is stale by comparing active milestone/slice/phase
+        const currentContent = readFileSync(stateFilePath, "utf-8");
+        const state = await deriveState(basePath);
+        const freshContent = buildStateMarkdownForCheck(state);
+
+        // Extract key fields for comparison — don't compare full content
+        // since timestamp/formatting differences are normal
+        const extractFields = (content: string) => {
+          const milestone = content.match(/\*\*Active Milestone:\*\*\s*(.+)/)?.[1]?.trim() ?? "";
+          const slice = content.match(/\*\*Active Slice:\*\*\s*(.+)/)?.[1]?.trim() ?? "";
+          const phase = content.match(/\*\*Phase:\*\*\s*(.+)/)?.[1]?.trim() ?? "";
+          return { milestone, slice, phase };
+        };
+
+        const current = extractFields(currentContent);
+        const fresh = extractFields(freshContent);
+
+        if (current.milestone !== fresh.milestone || current.slice !== fresh.slice || current.phase !== fresh.phase) {
+          issues.push({
+            severity: "warning",
+            code: "state_file_stale",
+            scope: "project",
+            unitId: "project",
+            message: `STATE.md is stale — shows "${current.phase}" but derived state is "${fresh.phase}"`,
+            file: ".gsd/STATE.md",
+            fixable: true,
+          });
+
+          if (shouldFix("state_file_stale")) {
+            await saveFile(stateFilePath, freshContent);
+            fixesApplied.push("rebuilt STATE.md from derived state");
+          }
+        }
+      }
+    }
+  } catch {
+    // Non-fatal — STATE.md check failed
+  }
+
+  // ── Gitignore drift ───────────────────────────────────────────────────
+  try {
+    const gitignorePath = join(basePath, ".gitignore");
+    if (existsSync(gitignorePath) && nativeIsRepo(basePath)) {
+      const content = readFileSync(gitignorePath, "utf-8");
+      const existingLines = new Set(
+        content.split("\n").map(l => l.trim()).filter(l => l && !l.startsWith("#")),
+      );
+
+      // Check for critical runtime patterns that must be present
+      const criticalPatterns = [
+        ".gsd/activity/",
+        ".gsd/runtime/",
+        ".gsd/auto.lock",
+        ".gsd/gsd.db",
+        ".gsd/completed-units.json",
+      ];
+
+      // If blanket .gsd/ or .gsd is present, all patterns are covered
+      const hasBlanketIgnore = existingLines.has(".gsd/") || existingLines.has(".gsd");
+
+      if (!hasBlanketIgnore) {
+        const missing = criticalPatterns.filter(p => !existingLines.has(p));
+        if (missing.length > 0) {
+          issues.push({
+            severity: "warning",
+            code: "gitignore_missing_patterns",
+            scope: "project",
+            unitId: "project",
+            message: `${missing.length} critical GSD runtime pattern(s) missing from .gitignore: ${missing.join(", ")}`,
+            file: ".gitignore",
+            fixable: true,
+          });
+
+          if (shouldFix("gitignore_missing_patterns")) {
+            ensureGitignore(basePath);
+            fixesApplied.push("added missing GSD runtime patterns to .gitignore");
+          }
+        }
+      }
+    }
+  } catch {
+    // Non-fatal — gitignore check failed
+  }
+
+  // ── External state symlink health ──────────────────────────────────────
+  try {
+    const localGsd = join(basePath, ".gsd");
+    if (existsSync(localGsd)) {
+      const stat = lstatSync(localGsd);
+
+      // Check for .gsd.migrating (failed migration)
+      const migratingPath = join(basePath, ".gsd.migrating");
+      if (existsSync(migratingPath)) {
+        issues.push({
+          severity: "error",
+          code: "failed_migration",
+          scope: "project",
+          unitId: "project",
+          message: "Found .gsd.migrating — a previous external state migration failed. State may be incomplete.",
+          file: ".gsd.migrating",
+          fixable: true,
+        });
+
+        if (shouldFix("failed_migration")) {
+          if (recoverFailedMigration(basePath)) {
+            fixesApplied.push("recovered failed migration (.gsd.migrating → .gsd)");
+          }
+        }
+      }
+
+      // Check symlink target exists
+      if (stat.isSymbolicLink()) {
+        try {
+          realpathSync(localGsd);
+        } catch {
+          issues.push({
+            severity: "error",
+            code: "broken_symlink",
+            scope: "project",
+            unitId: "project",
+            message: ".gsd symlink target does not exist. External state directory may have been deleted.",
+            file: ".gsd",
+            fixable: false,
+          });
+        }
+      }
+    }
+  } catch {
+    // Non-fatal — external state check failed
+  }
+
+  // ── Numbered .gsd collision variants (#2205) ───────────────────────────
+  // macOS APFS can create ".gsd 2", ".gsd 3" etc. when a directory blocks
+  // symlink creation. These must be removed so the canonical .gsd is used.
+  try {
+    const variantPattern = /^\.gsd \d+$/;
+    const entries = readdirSync(basePath);
+    const variants = entries.filter(e => variantPattern.test(e));
+    if (variants.length > 0) {
+      for (const v of variants) {
+        issues.push({
+          severity: "warning",
+          code: "numbered_gsd_variant",
+          scope: "project",
+          unitId: "project",
+          message: `Found macOS collision variant "${v}" — this can cause GSD state to appear deleted.`,
+          file: v,
+          fixable: true,
+        });
+      }
+
+      if (shouldFix("numbered_gsd_variant")) {
+        const removed = cleanNumberedGsdVariants(basePath);
+        for (const name of removed) {
+          fixesApplied.push(`removed numbered .gsd variant: ${name}`);
+        }
+      }
+    }
+  } catch {
+    // Non-fatal — variant check failed
+  }
+
+  // ── Metrics ledger integrity ───────────────────────────────────────────
+  try {
+    const metricsPath = join(root, "metrics.json");
+    if (existsSync(metricsPath)) {
+      try {
+        const raw = readFileSync(metricsPath, "utf-8");
+        const ledger = JSON.parse(raw);
+        if (ledger.version !== 1 || !Array.isArray(ledger.units)) {
+          issues.push({
+            severity: "warning",
+            code: "metrics_ledger_corrupt",
+            scope: "project",
+            unitId: "project",
+            message: "metrics.json has an unexpected structure (version !== 1 or units is not an array) — metrics data may be unreliable",
+            file: ".gsd/metrics.json",
+            fixable: false,
+          });
+        }
+      } catch {
+        issues.push({
+          severity: "warning",
+          code: "metrics_ledger_corrupt",
+          scope: "project",
+          unitId: "project",
+          message: "metrics.json is not valid JSON — metrics data may be corrupt",
+          file: ".gsd/metrics.json",
+          fixable: false,
+        });
+      }
+    }
+  } catch {
+    // Non-fatal — metrics check failed
+  }
+
+  // ── Metrics ledger bloat ──────────────────────────────────────────────
+  // The metrics ledger has no TTL and grows by one entry per completed unit.
+  // At 50 units/day a project can accumulate tens of thousands of entries over
+  // months of use. Prune to the newest 1500 when the threshold is exceeded.
+  try {
+    const metricsFilePath = join(root, "metrics.json");
+    if (existsSync(metricsFilePath)) {
+      try {
+        const raw = readFileSync(metricsFilePath, "utf-8");
+        const parsed = JSON.parse(raw);
+        const BLOAT_UNITS_THRESHOLD = 2000;
+        if (parsed.version === 1 && Array.isArray(parsed.units) && parsed.units.length > BLOAT_UNITS_THRESHOLD) {
+          const fileSizeMB = (statSync(metricsFilePath).size / (1024 * 1024)).toFixed(1);
+          issues.push({
+            severity: "warning",
+            code: "metrics_ledger_bloat",
+            scope: "project",
+            unitId: "project",
+            message: `metrics.json has ${parsed.units.length} unit entries (${fileSizeMB}MB) — threshold is ${BLOAT_UNITS_THRESHOLD}. Run /gsd doctor --fix to prune to the newest 1500 entries.`,
+            file: ".gsd/metrics.json",
+            fixable: true,
+          });
+          if (shouldFix("metrics_ledger_bloat")) {
+            const { pruneMetricsLedger } = await import("./metrics.js");
+            const removed = pruneMetricsLedger(basePath, 1500);
+            fixesApplied.push(`pruned metrics ledger: removed ${removed} oldest entries (${parsed.units.length - removed} remain)`);
+          }
+        }
+      } catch {
+        // JSON parse failed — already handled by the integrity check above
+      }
+    }
+  } catch {
+    // Non-fatal — metrics bloat check failed
+  }
+
+  // ── Large planning file detection ──────────────────────────────────────
+  // Files over 100KB can cause LLM context pressure. Report the worst offenders.
+  try {
+    const MAX_FILE_BYTES = 100 * 1024; // 100KB
+    const milestonesPath = milestonesDir(basePath);
+    if (existsSync(milestonesPath)) {
+      const largeFiles: Array<{ path: string; sizeKB: number }> = [];
+      function scanForLargeFiles(dir: string, depth = 0): void {
+        if (depth > 6) return;
+        try {
+          for (const entry of readdirSync(dir)) {
+            const full = join(dir, entry);
+            try {
+              const s = statSync(full);
+              if (s.isDirectory()) { scanForLargeFiles(full, depth + 1); continue; }
+              if (entry.endsWith(".md") && s.size > MAX_FILE_BYTES) {
+                largeFiles.push({ path: full.replace(basePath + "/", ""), sizeKB: Math.round(s.size / 1024) });
+              }
+            } catch { /* skip entry */ }
+          }
+        } catch { /* skip dir */ }
+      }
+      scanForLargeFiles(milestonesPath);
+      if (largeFiles.length > 0) {
+        largeFiles.sort((a, b) => b.sizeKB - a.sizeKB);
+        const worst = largeFiles[0]!;
+        issues.push({
+          severity: "warning",
+          code: "large_planning_file",
+          scope: "project",
+          unitId: "project",
+          message: `${largeFiles.length} planning file(s) exceed 100KB — largest: ${worst.path} (${worst.sizeKB}KB). Large files cause LLM context pressure.`,
+          file: worst.path,
+          fixable: false,
+        });
+      }
+    }
+  } catch {
+    // Non-fatal — large file scan failed
+  }
+
+  // ── Snapshot ref bloat ────────────────────────────────────────────────
+  // refs/gsd/snapshots/ accumulate over time. Prune to newest 5 per label
+  // when total count exceeds threshold.
+  try {
+    if (nativeIsRepo(basePath)) {
+      const refs = nativeForEachRef(basePath, "refs/gsd/snapshots/");
+      if (refs.length > 50) {
+        issues.push({
+          severity: "warning",
+          code: "snapshot_ref_bloat",
+          scope: "project",
+          unitId: "project",
+          message: `${refs.length} snapshot refs found under refs/gsd/snapshots/ — pruning to newest 5 per label will reclaim git storage`,
+          fixable: true,
+        });
+
+        if (shouldFix("snapshot_ref_bloat")) {
+          const byLabel = new Map<string, string[]>();
+          for (const ref of refs) {
+            const parts = ref.split("/");
+            const label = parts.slice(0, -1).join("/");
+            if (!byLabel.has(label)) byLabel.set(label, []);
+            byLabel.get(label)!.push(ref);
+          }
+          let pruned = 0;
+          for (const [, labelRefs] of byLabel) {
+            const sorted = labelRefs.sort();
+            for (const old of sorted.slice(0, -5)) {
+              try {
+                nativeUpdateRef(basePath, old);
+                pruned++;
+              } catch { /* skip */ }
+            }
+          }
+          if (pruned > 0) {
+            fixesApplied.push(`pruned ${pruned} old snapshot ref(s)`);
+          }
+        }
+      }
+    }
+  } catch {
+    // Non-fatal — snapshot ref check failed
+  }
+}
+
+/**
+ * Build STATE.md markdown content from derived state.
+ * Local helper used by checkRuntimeHealth for STATE.md drift detection and repair.
+ */
+function buildStateMarkdownForCheck(state: Awaited<ReturnType<typeof deriveState>>): string {
+  const lines: string[] = [];
+  lines.push("# GSD State", "");
+
+  const activeMilestone = state.activeMilestone
+    ? `${state.activeMilestone.id}: ${state.activeMilestone.title}`
+    : "None";
+  const activeSlice = state.activeSlice
+    ? `${state.activeSlice.id}: ${state.activeSlice.title}`
+    : "None";
+
+  lines.push(`**Active Milestone:** ${activeMilestone}`);
+  lines.push(`**Active Slice:** ${activeSlice}`);
+  lines.push(`**Phase:** ${state.phase}`);
+  if (state.requirements) {
+    lines.push(`**Requirements Status:** ${state.requirements.active} active · ${state.requirements.validated} validated · ${state.requirements.deferred} deferred · ${state.requirements.outOfScope} out of scope`);
+  }
+  lines.push("");
+  lines.push("## Milestone Registry");
+
+  for (const entry of state.registry) {
+    const glyph = entry.status === "complete" ? "\u2705" : entry.status === "active" ? "\uD83D\uDD04" : entry.status === "parked" ? "\u23F8\uFE0F" : "\u2B1C";
+    lines.push(`- ${glyph} **${entry.id}:** ${entry.title}`);
+  }
+
+  lines.push("");
+  lines.push("## Recent Decisions");
+  if (state.recentDecisions.length > 0) {
+    for (const decision of state.recentDecisions) lines.push(`- ${decision}`);
+  } else {
+    lines.push("- None recorded");
+  }
+
+  lines.push("");
+  lines.push("## Blockers");
+  if (state.blockers.length > 0) {
+    for (const blocker of state.blockers) lines.push(`- ${blocker}`);
+  } else {
+    lines.push("- None");
+  }
+
+  lines.push("");
+  lines.push("## Next Action");
+  lines.push(state.nextAction || "None");
+  lines.push("");
+
+  return lines.join("\n");
+}