test(electron): make dev-resolution tests self-sufficient on fresh clones (#689)

* test(electron): isolate dev-resolution fixtures via CODEBURN_DEV_REPO_ROOT

Rework of the #681 fix per review: instead of stubbing the real repo
dist/cli.js with snapshot-restore, the Vite-dev resolution branch gains a
CODEBURN_DEV_REPO_ROOT override (matching the CODEBURN_PATH_DIRS precedent)
so the whole fixture lives in a per-test tmpdir. With the env unset the
resolution order is byte-identical to before.

- covers all three fresh-clone failures on current main, including the
  resolveTarget dev-repo-beats-bundled case
- deletes the snapshot-restore machinery, the parent-path precondition and
  the beforeAll repo-scanning guard
- tests assert both override-set (tmpdir wins) and override-unset behavior

Closes #681

* test(electron): drop environment-coupled null assertion for unset dev-root override

The override-unset case resolved <repo>/dist/cli.js whenever a build had
run, so the toBeNull() assertion depended on the absence of a gitignored
artifact. The override-set tests already prove the new branch and the
non-Vite test covers the null path.

app/electron/cli.test.ts

@@ -12,6 +12,7 @@ const originalPathDirs = process.env.CODEBURN_PATH_DIRS
 const originalPathFile = process.env.CODEBURN_CLI_PATH_FILE
 const originalViteUrl = process.env.VITE_DEV_SERVER_URL
 const originalBundled = process.env.CODEBURN_BUNDLED_CLI
+const originalDevRepoRoot = process.env.CODEBURN_DEV_REPO_ROOT
 
 /** Writes an executable node script and points CODEBURN_BIN at it. */
 function fakeBin(name: string, body: string): string {
@@ -22,6 +23,17 @@ function fakeBin(name: string, body: string): string {
   return p
 }
 
+/** Writes the repo CLI under this test's isolated dev-root override. */
+function fakeDevRepoCli(): string {
+  const repoRoot = join(dir, 'dev-repo')
+  const p = join(repoRoot, 'dist', 'cli.js')
+  mkdirSync(dirname(p), { recursive: true })
+  writeFileSync(p, '#!/usr/bin/env node\n', { mode: 0o755 })
+  chmodSync(p, 0o755)
+  process.env.CODEBURN_DEV_REPO_ROOT = repoRoot
+  return p
+}
+
 beforeEach(() => {
   dir = mkdtempSync(join(tmpdir(), 'codeburn-cli-'))
 })
@@ -37,6 +49,8 @@ afterEach(() => {
   else process.env.VITE_DEV_SERVER_URL = originalViteUrl
   if (originalBundled === undefined) delete process.env.CODEBURN_BUNDLED_CLI
   else process.env.CODEBURN_BUNDLED_CLI = originalBundled
+  if (originalDevRepoRoot === undefined) delete process.env.CODEBURN_DEV_REPO_ROOT
+  else process.env.CODEBURN_DEV_REPO_ROOT = originalDevRepoRoot
   rmSync(dir, { recursive: true, force: true })
 })
 
@@ -46,8 +60,9 @@ describe('resolveCodeburnPath (Vite development)', () => {
     process.env.CODEBURN_PATH_DIRS = ''
     process.env.CODEBURN_CLI_PATH_FILE = join(dir, 'no-persisted-path')
     process.env.VITE_DEV_SERVER_URL = 'http://localhost:5173'
+    const devBin = fakeDevRepoCli()
 
-    expect(resolveCodeburnPath()).toMatch(/dist\/cli\.js$/)
+    expect(resolveCodeburnPath()).toBe(devBin)
   })
 
   it('prefers the repo dev CLI over a persisted-path file (stale global) in dev', () => {
@@ -63,9 +78,10 @@ describe('resolveCodeburnPath (Vite development)', () => {
     writeFileSync(persistedFile, persistedTarget)
     process.env.CODEBURN_CLI_PATH_FILE = persistedFile
     process.env.VITE_DEV_SERVER_URL = 'http://localhost:5173'
+    const devBin = fakeDevRepoCli()
 
     const resolved = resolveCodeburnPath()
-    expect(resolved).toMatch(/dist\/cli\.js$/)
+    expect(resolved).toBe(devBin)
     expect(resolved).not.toBe(persistedTarget)
   })
 
@@ -120,10 +136,10 @@ describe('resolveTarget (bundled CLI in the packaged app)', () => {
     process.env.CODEBURN_CLI_PATH_FILE = join(dir, 'no-persisted-path')
     process.env.CODEBURN_BUNDLED_CLI = bundledEntry('bundled.js')
     process.env.VITE_DEV_SERVER_URL = 'http://localhost:5173'
+    const devBin = fakeDevRepoCli()
 
     const target = resolveTarget()
-    expect(target?.kind).toBe('external')
-    expect(target && target.kind === 'external' ? target.bin : '').toMatch(/dist\/cli\.js$/)
+    expect(target).toEqual({ kind: 'external', bin: devBin })
   })
 
   it('falls through when CODEBURN_BUNDLED_CLI points at a missing file', () => {

app/electron/cli.ts

@@ -255,12 +255,19 @@ export function resolveTarget(): CliTarget | null {
   // freshly-built CLI over a stale globally-installed/persisted one, so
   // newly-added commands (sessions/compare/act JSON) work without CODEBURN_BIN.
   if (process.env.VITE_DEV_SERVER_URL) {
-    const devBin = join(__dirname, '..', '..', '..', 'dist', 'cli.js')
-    if (isExecutableFile(devBin)) return { kind: 'external', bin: devBin }
-    // Vitest loads this source module from app/electron rather than the emitted
-    // app/dist/electron directory; keep the same repo CLI discoverable there.
-    const sourceDevBin = join(__dirname, '..', '..', 'dist', 'cli.js')
-    if (isExecutableFile(sourceDevBin)) return { kind: 'external', bin: sourceDevBin }
+    const devRepoRoot = process.env.CODEBURN_DEV_REPO_ROOT
+    if (devRepoRoot) {
+      // Test/advanced override, matching CODEBURN_PATH_DIRS: keep dev lookup in an isolated repo root.
+      const devBin = join(devRepoRoot, 'dist', 'cli.js')
+      if (isExecutableFile(devBin)) return { kind: 'external', bin: devBin }
+    } else {
+      const devBin = join(__dirname, '..', '..', '..', 'dist', 'cli.js')
+      if (isExecutableFile(devBin)) return { kind: 'external', bin: devBin }
+      // Vitest loads this source module from app/electron rather than the emitted
+      // app/dist/electron directory; keep the same repo CLI discoverable there.
+      const sourceDevBin = join(__dirname, '..', '..', 'dist', 'cli.js')
+      if (isExecutableFile(sourceDevBin)) return { kind: 'external', bin: sourceDevBin }
+    }
   }
 
   // Packaged app: main.ts sets CODEBURN_BUNDLED_CLI to resources/cli/dist/cli.js.