chore: remove dead worktree code and unused methods

Delete unused resource-version.ts (functions duplicated in auto-worktree-sync.ts
with zero imports). Remove GitServiceImpl.git() private method with no call sites.
Clean up orphaned section headers and dangling JSDoc in git-service.ts.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/resources/extensions/gsd/git-service.ts

@@ -454,11 +454,6 @@ export class GitServiceImpl {
     this._milestoneId = milestoneId;
   }
 
-  /** Convenience wrapper: run git in this repo's basePath. */
-  private git(args: string[], options: { allowFailure?: boolean; input?: string } = {}): string {
-    return runGit(this.basePath, args, options);
-  }
-
   /**
    * Smart staging: `git add -A` excluding GSD runtime paths via pathspec.
    * Falls back to plain `git add -A` if the exclusion pathspec fails.
@@ -617,11 +612,6 @@ export class GitServiceImpl {
     return nativeGetCurrentBranch(this.basePath);
   }
 
-  /** True if currently on a GSD slice branch. */
-  // ─── Branch Lifecycle ──────────────────────────────────────────────────
-
-  // ─── S05 Features ─────────────────────────────────────────────────────
-
   /**
    * Create a snapshot ref for the given label (typically a slice branch name).
    * Gated on prefs.snapshots === true. Ref path: refs/gsd/snapshots/<label>/<timestamp>
@@ -682,8 +672,6 @@ export class GitServiceImpl {
     }
   }
 
-  // ─── Merge ─────────────────────────────────────────────────────────────
-
 }
 
 // ─── Draft PR Creation ─────────────────────────────────────────────────────

src/resources/extensions/gsd/resource-version.ts

@@ -1,101 +0,0 @@
-/**
- * Resource version tracking and stale worktree detection.
- *
- * Staleness detection for managed GSD resources and utilities
- * for escaping stale worktree cwd after milestone teardown.
- */
-
-import { existsSync, readdirSync, unlinkSync } from "node:fs";
-import { loadJsonFileOrNull } from "./json-persistence.js";
-import { join } from "node:path";
-import { homedir } from "node:os";
-import { resolveProjectRoot } from "./worktree.js";
-
-const gsdHome = process.env.GSD_HOME || join(homedir(), ".gsd");
-
-// ─── Resource Staleness ───────────────────────────────────────────────────
-
-/**
- * Read the resource version (semver) from the managed-resources manifest.
- * Uses gsdVersion instead of syncedAt so that launching a second session
- * doesn't falsely trigger staleness (#804).
- */
-function isManifestWithVersion(data: unknown): data is { gsdVersion: string } {
-  return data !== null && typeof data === "object" && "gsdVersion" in data! && typeof (data as Record<string, unknown>).gsdVersion === "string";
-}
-
-export function readResourceVersion(): string | null {
-  const agentDir = process.env.GSD_CODING_AGENT_DIR || join(gsdHome, "agent");
-  const manifestPath = join(agentDir, "managed-resources.json");
-  const manifest = loadJsonFileOrNull(manifestPath, isManifestWithVersion);
-  return manifest?.gsdVersion ?? null;
-}
-
-/**
- * Check if managed resources have been updated since session start.
- * Returns a warning message if stale, null otherwise.
- */
-export function checkResourcesStale(versionOnStart: string | null): string | null {
-  if (versionOnStart === null) return null;
-  const current = readResourceVersion();
-  if (current === null) return null;
-  if (current !== versionOnStart) {
-    return "GSD resources were updated since this session started. Restart gsd to load the new code.";
-  }
-  return null;
-}
-
-// ─── Stale Worktree Escape ────────────────────────────────────────────────
-
-/**
- * Detect and escape a stale worktree cwd (#608).
- *
- * After milestone completion + merge, the worktree directory is removed but
- * the process cwd may still point inside `.gsd/worktrees/<MID>/`.
- * When a new session starts, `process.cwd()` is passed as `base` to startAuto
- * and all subsequent writes land in the wrong directory. This function detects
- * that scenario and chdir back to the project root.
- *
- * Returns the corrected base path.
- */
-export function escapeStaleWorktree(base: string): string {
-  const projectRoot = resolveProjectRoot(base);
-  if (projectRoot === base) return base;
-  try {
-    process.chdir(projectRoot);
-  } catch {
-    return base;
-  }
-  return projectRoot;
-}
-
-/**
- * Clean stale runtime unit files for completed milestones.
- *
- * After restart, stale runtime/units/*.json from prior milestones can
- * cause deriveState to resume the wrong milestone (#887). Removes files
- * for milestones that have a SUMMARY (fully complete).
- */
-export function cleanStaleRuntimeUnits(
-  gsdRootPath: string,
-  hasMilestoneSummary: (mid: string) => boolean,
-): number {
-  const runtimeUnitsDir = join(gsdRootPath, "runtime", "units");
-  if (!existsSync(runtimeUnitsDir)) return 0;
-
-  let cleaned = 0;
-  try {
-    for (const file of readdirSync(runtimeUnitsDir)) {
-      if (!file.endsWith(".json")) continue;
-      const midMatch = file.match(/(M\d+(?:-[a-z0-9]{6})?)/);
-      if (!midMatch) continue;
-      if (hasMilestoneSummary(midMatch[1])) {
-        try {
-          unlinkSync(join(runtimeUnitsDir, file));
-          cleaned++;
-        } catch { /* non-fatal */ }
-      }
-    }
-  } catch { /* non-fatal */ }
-  return cleaned;
-}