fix(ultraplan-local): Bug 3 — wire frontmatter consistency check into /ultracontinue Phase 1.5

Step 8 of v3.4.1 plan.

commands/ultracontinue-local.md:
- New Phase 1.5 between Phase 1 and Phase 2 — runs the
  next-session-prompt-validator in --consistency mode when both candidates
  exist (plugin-root + project-dir). Refuses on producer mismatch with
  fresh candidates, downgrades stale candidate to a warning, downgrades
  >24h wall-clock drift to a soft warning.
- Anti-substitution rule applies — paths emitted as concrete tokens, not
  template placeholders.

lib/validators/next-session-prompt-validator.mjs:
- Sharpen NEXT_SESSION_PROMPT_PRODUCER_MISMATCH error message to include
  the literal "produced_by" field name so consumers (and operators) can
  trace the disagreement back to the YAML key.

tests/commands/ultracontinue.test.mjs:
- Test (Bug 3 prose) — Phase 1.5 header present, references validator,
  appears between Phase 1 and Phase 2 in document order.
- Test (Bug 3 e) — tmp project dir with state file + two prompt files
  with mismatched producers, both fresh relative to state.updated_at;
  CLI consistency mode exits non-zero, JSON stdout surfaces
  NEXT_SESSION_PROMPT_PRODUCER_MISMATCH with both paths and the
  "produced_by" token in the message.

Tests 346 -> 348 (+2).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

plugins/ultraplan-local/tests/commands/ultracontinue.test.mjs

@@ -15,6 +15,7 @@ import { mkdtempSync, mkdirSync, writeFileSync, readFileSync, rmSync } from 'nod
 import { tmpdir } from 'node:os';
 import { dirname, join } from 'node:path';
 import { fileURLToPath } from 'node:url';
+import { execFileSync } from 'node:child_process';
 import { runHook } from '../helpers/hook-helper.mjs';
 
 const HERE = dirname(fileURLToPath(import.meta.url));
@@ -170,6 +171,80 @@ test('ultracontinue Bug 2 — pre-bash-executor ALLOWS resolved validator invoca
   assert.strictEqual(code, 0, 'pre-bash-executor must not block resolved validator invocations');
 });
 
+// ---------------------------------------------------------------
+// Step 8 — Bug 3 regression test (Phase 1.5 consistency wire-up)
+// ---------------------------------------------------------------
+
+test('ultracontinue Bug 3 — Phase 1.5 documents consistency check between Phase 1 and Phase 2', () => {
+  const cmd = readCommand();
+  // Phase 1.5 must exist literally in the prose between Phase 1 and Phase 2.
+  assert.match(cmd, /## Phase 1\.5 /, 'Phase 1.5 header must be present');
+  assert.match(cmd, /next-session-prompt-validator/, 'Phase 1.5 must invoke next-session-prompt-validator');
+
+  const phase15Idx = cmd.indexOf('## Phase 1.5 ');
+  const phase2Idx = cmd.indexOf('## Phase 2 ');
+  assert.ok(phase15Idx !== -1 && phase2Idx !== -1 && phase15Idx < phase2Idx,
+    'Phase 1.5 must appear before Phase 2');
+});
+
+test('ultracontinue Bug 3 (e) — CLI consistency mode flags producer mismatch in JSON output', () => {
+  const root = mkdtempSync(join(tmpdir(), 'ultracontinue-fm-'));
+  try {
+    const projectDir = join(root, '.claude', 'projects', '2026-05-04-fixture-c');
+    mkdirSync(projectDir, { recursive: true });
+
+    // State file (status: in_progress, updated_at = T-base)
+    const stateUpdatedAt = '2026-05-04T15:00:00.000Z';
+    writeFileSync(
+      join(projectDir, '.session-state.local.json'),
+      JSON.stringify({
+        schema_version: 1,
+        project: projectDir,
+        next_session_brief_path: join(projectDir, 'brief.md'),
+        next_session_label: 'Session 2',
+        status: 'in_progress',
+        updated_at: stateUpdatedAt,
+      }, null, 2),
+    );
+
+    // Project-dir prompt: produced_by ultraexecute-local at T-1
+    const projectPrompt = join(projectDir, 'NEXT-SESSION-PROMPT.local.md');
+    writeFileSync(projectPrompt,
+      '---\nproduced_by: ultraexecute-local\nproduced_at: 2026-05-04T15:30:00.000Z\n---\n\n# Session 2\n');
+
+    // Plugin-root prompt: produced_by graceful-handoff at T-0 (newer)
+    const pluginPrompt = join(root, 'NEXT-SESSION-PROMPT.local.md');
+    writeFileSync(pluginPrompt,
+      '---\nproduced_by: graceful-handoff\nproduced_at: 2026-05-04T15:31:00.000Z\n---\n\n# A2 master\n');
+
+    // Both fresh relative to state.updated_at → producer mismatch must hard-fail.
+    let exitCode = 0;
+    let stdout = '';
+    try {
+      stdout = execFileSync(process.execPath, [
+        join(ROOT, 'lib', 'validators', 'next-session-prompt-validator.mjs'),
+        '--json',
+        '--consistency',
+        projectPrompt,
+        pluginPrompt,
+      ], { encoding: 'utf-8', cwd: ROOT });
+    } catch (e) {
+      exitCode = e.status;
+      stdout = e.stdout ? e.stdout.toString() : '';
+    }
+    assert.notEqual(exitCode, 0, 'consistency CLI must exit non-zero on producer mismatch');
+    const parsed = JSON.parse(stdout);
+    assert.equal(parsed.valid, false);
+    const mismatch = parsed.errors.find(e => e.code === 'NEXT_SESSION_PROMPT_PRODUCER_MISMATCH');
+    assert.ok(mismatch, 'must surface NEXT_SESSION_PROMPT_PRODUCER_MISMATCH error');
+    assert.match(mismatch.message, new RegExp(projectPrompt.replace(/[/\\]/g, '.')), 'error message must reference project-dir prompt path');
+    assert.match(mismatch.message, new RegExp(pluginPrompt.replace(/[/\\]/g, '.')), 'error message must reference plugin-root prompt path');
+    assert.match(mismatch.message, /produced_by/i, 'error message must mention produced_by');
+  } finally {
+    rmSync(root, { recursive: true, force: true });
+  }
+});
+
 test('ultracontinue Bug 2 — Phase 2 contains no {state-file-path} or any {curly-template} placeholder', () => {
   // (d-2) Pattern D structure test. The fix must eliminate the
   // {state-file-path} placeholder and any other {anything} curly-brace