feat: migrate eval storage to project-scoped paths

Move eval results and E2E run artifacts from ~/.gstack-dev/evals/ to
~/.gstack/projects/$SLUG/evals/ so each project's eval history lives
alongside its other gstack data. Falls back to legacy path if slug
detection fails.

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

scripts/eval-compare.ts

@@ -15,10 +15,11 @@ import {
   findPreviousRun,
   compareEvalResults,
   formatComparison,
+  getProjectEvalDir,
 } from '../test/helpers/eval-store';
 import type { EvalResult } from '../test/helpers/eval-store';
 
-const EVAL_DIR = path.join(os.homedir(), '.gstack-dev', 'evals');
+const EVAL_DIR = getProjectEvalDir();
 
 function loadResult(filepath: string): EvalResult {
   // Resolve relative to EVAL_DIR if not absolute

scripts/eval-list.ts

@@ -8,8 +8,9 @@
 import * as fs from 'fs';
 import * as path from 'path';
 import * as os from 'os';
+import { getProjectEvalDir } from '../test/helpers/eval-store';
 
-const EVAL_DIR = path.join(os.homedir(), '.gstack-dev', 'evals');
+const EVAL_DIR = getProjectEvalDir();
 
 // Parse args
 const args = process.argv.slice(2);

scripts/eval-summary.ts

@@ -9,8 +9,9 @@ import * as fs from 'fs';
 import * as path from 'path';
 import * as os from 'os';
 import type { EvalResult } from '../test/helpers/eval-store';
+import { getProjectEvalDir } from '../test/helpers/eval-store';
 
-const EVAL_DIR = path.join(os.homedir(), '.gstack-dev', 'evals');
+const EVAL_DIR = getProjectEvalDir();
 
 let files: string[];
 try {

test/helpers/eval-store.ts

@@ -2,7 +2,7 @@
  * Eval result persistence and comparison.
  *
  * EvalCollector accumulates test results, writes them to
- * ~/.gstack-dev/evals/{version}-{branch}-{tier}-{timestamp}.json,
+ * ~/.gstack/projects/$SLUG/evals/{version}-{branch}-{tier}-{timestamp}.json,
  * prints a summary table, and auto-compares with the previous run.
  *
  * Comparison functions are exported for reuse by the eval:compare CLI.
@@ -14,7 +14,32 @@ import * as os from 'os';
 import { spawnSync } from 'child_process';
 
 const SCHEMA_VERSION = 1;
-const DEFAULT_EVAL_DIR = path.join(os.homedir(), '.gstack-dev', 'evals');
+const LEGACY_EVAL_DIR = path.join(os.homedir(), '.gstack-dev', 'evals');
+
+/**
+ * Detect project-scoped eval dir via gstack-slug.
+ * Falls back to legacy ~/.gstack-dev/evals/ if slug detection fails.
+ */
+export function getProjectEvalDir(): string {
+  try {
+    // Try repo-local gstack-slug first, then global install
+    const localSlug = spawnSync('bash', ['-c', '.claude/skills/gstack/bin/gstack-slug 2>/dev/null || ~/.claude/skills/gstack/bin/gstack-slug 2>/dev/null'], {
+      stdio: 'pipe', timeout: 3000,
+    });
+    const output = localSlug.stdout?.toString().trim();
+    if (output) {
+      const slugMatch = output.match(/^SLUG=(.+)$/m);
+      if (slugMatch && slugMatch[1]) {
+        const dir = path.join(os.homedir(), '.gstack', 'projects', slugMatch[1], 'evals');
+        fs.mkdirSync(dir, { recursive: true });
+        return dir;
+      }
+    }
+  } catch { /* fall through */ }
+  return LEGACY_EVAL_DIR;
+}
+
+const DEFAULT_EVAL_DIR = getProjectEvalDir();
 
 // --- Interfaces ---
 

test/helpers/session-runner.ts

@@ -9,9 +9,11 @@
 import * as fs from 'fs';
 import * as path from 'path';
 import * as os from 'os';
+import { getProjectEvalDir } from './eval-store';
 
 const GSTACK_DEV_DIR = path.join(os.homedir(), '.gstack-dev');
-const HEARTBEAT_PATH = path.join(GSTACK_DEV_DIR, 'e2e-live.json');
+const HEARTBEAT_PATH = path.join(GSTACK_DEV_DIR, 'e2e-live.json'); // heartbeat stays global
+const PROJECT_DIR = path.dirname(getProjectEvalDir()); // ~/.gstack/projects/$SLUG/
 
 /** Sanitize test name for use as filename: strip leading slashes, replace / with - */
 export function sanitizeTestName(name: string): string {
@@ -144,7 +146,7 @@ export async function runSkillTest(options: {
   const safeName = testName ? sanitizeTestName(testName) : null;
   if (runId) {
     try {
-      runDir = path.join(GSTACK_DEV_DIR, 'e2e-runs', runId);
+      runDir = path.join(PROJECT_DIR, 'e2e-runs', runId);
       fs.mkdirSync(runDir, { recursive: true });
     } catch { /* non-fatal */ }
   }