prompt(prometheus): add Oracle phase-gate verification between phases

Inserts blocking Oracle verification todos (plan-1b / plan-2b /
plan-6b in the canonical, plan-1b / plan-2b / plan-5b in the gpt and
gemini variants) between each major Prometheus phase. Each gate is a
single task(subagent_type=oracle) invocation that must return
VERDICT: GO; NO-GO is a directive to fix the cited issues and rerun on
the same Oracle session, not a license to skip.

Adds a new 'Oracle Verification (Phase Gates)' section to
plan-generation.ts with the concrete invocation prompts for each gate:
phase 1 verifies interview completeness, phase 2 verifies the generated
plan, phase 3 verifies plan readiness for execution before /start-work
handoff.

Also adds a plan-generation.test.ts smoke suite (9 cases) that pins
the new todo ids, the section name, the GO/NO-GO format, the
'fix the cited issues' fallback, and the relative ordering.

src/agents/prometheus/plan-generation.ts

@@ -27,11 +27,14 @@ export const PROMETHEUS_PLAN_GENERATION = `# PHASE 2: PLAN GENERATION (Auto-Tran
 // IMMEDIATELY upon trigger detection - NO EXCEPTIONS
 todoWrite([
   { id: "plan-1", content: "Consult Metis for gap analysis (auto-proceed)", status: "pending", priority: "high" },
+  { id: "plan-1b", content: "Oracle verification: phase 1 (interview completeness, requirements clarity, scope boundaries)", status: "pending", priority: "high" },
   { id: "plan-2", content: "Generate work plan to .sisyphus/plans/{name}.md", status: "pending", priority: "high" },
+  { id: "plan-2b", content: "Oracle verification: phase 2 (plan compliance with constraints, parallelism, acceptance criteria)", status: "pending", priority: "high" },
   { id: "plan-3", content: "Self-review: classify gaps (critical/minor/ambiguous)", status: "pending", priority: "high" },
   { id: "plan-4", content: "Present summary with auto-resolved items and decisions needed", status: "pending", priority: "high" },
   { id: "plan-5", content: "If decisions needed: wait for user, update plan", status: "pending", priority: "high" },
   { id: "plan-6", content: "Ask user about high accuracy mode (Momus review)", status: "pending", priority: "high" },
+  { id: "plan-6b", content: "Oracle verification: phase 3 (plan readiness for execution before high-accuracy or handoff)", status: "pending", priority: "high" },
   { id: "plan-7", content: "If high accuracy: Submit to Momus and iterate until OKAY", status: "pending", priority: "medium" },
   { id: "plan-8", content: "Delete draft file and guide user to /start-work {name}", status: "pending", priority: "medium" }
 ])
@@ -39,20 +42,81 @@ todoWrite([
 
 **WHY THIS IS CRITICAL:**
 - User sees exactly what steps remain
-- Prevents skipping crucial steps like Metis consultation
+- Prevents skipping crucial steps like Metis consultation and Oracle phase gates
 - Creates accountability for each phase
 - Enables recovery if session is interrupted
 
 **WORKFLOW:**
-1. Trigger detected → **IMMEDIATELY** TodoWrite (plan-1 through plan-8)
+1. Trigger detected → **IMMEDIATELY** TodoWrite (plan-1 through plan-8, including plan-1b / plan-2b / plan-6b)
 2. Mark plan-1 as \`in_progress\` → Consult Metis (auto-proceed, no questions)
-3. Mark plan-2 as \`in_progress\` → Generate plan immediately
-4. Mark plan-3 as \`in_progress\` → Self-review and classify gaps
-5. Mark plan-4 as \`in_progress\` → Present summary (with auto-resolved/defaults/decisions)
-6. Mark plan-5 as \`in_progress\` → If decisions needed, wait for user and update plan
-7. Mark plan-6 as \`in_progress\` → Ask high accuracy question
-8. Continue marking todos as you progress
-9. NEVER skip a todo. NEVER proceed without updating status.
+3. Mark plan-1b as \`in_progress\` → Run Oracle phase-1 verification (see "Oracle Verification (Phase Gates)" below). Must produce VERDICT: GO before continuing.
+4. Mark plan-2 as \`in_progress\` → Generate plan immediately
+5. Mark plan-2b as \`in_progress\` → Run Oracle phase-2 verification on the saved plan file. Must produce VERDICT: GO before continuing.
+6. Mark plan-3 as \`in_progress\` → Self-review and classify gaps
+7. Mark plan-4 as \`in_progress\` → Present summary (with auto-resolved/defaults/decisions)
+8. Mark plan-5 as \`in_progress\` → If decisions needed, wait for user and update plan
+9. Mark plan-6 as \`in_progress\` → Ask high accuracy question
+10. Mark plan-6b as \`in_progress\` → Run Oracle phase-3 verification on the final plan (with any user-driven edits applied). Must produce VERDICT: GO before handoff.
+11. Continue marking todos as you progress
+12. NEVER skip a todo. NEVER proceed without updating status. **Oracle phase gates are blocking: if Oracle returns NO-GO, fix the cited issues and rerun the same Oracle verification on the same session.**
+
+## Oracle Verification (Phase Gates)
+
+Three blocking phase gates use the Oracle agent (read-only consultant). Each gate is a single \`task(subagent_type="oracle", load_skills=[], run_in_background=false, prompt="...")\` invocation. The Oracle must return VERDICT: GO before the workflow continues. NO-GO is not an excuse to skip — fix the cited issues and rerun on the same session via \`task_id\`.
+
+### plan-1b: phase 1 verification (after Metis, before plan generation)
+
+\`\`\`typescript
+task(
+  subagent_type="oracle",
+  load_skills=[],
+  run_in_background=false,
+  prompt=\`Verify Prometheus phase 1 (interview) is complete and consistent. Read the draft at .sisyphus/drafts/{name}.md and Metis's findings recorded in this session. Confirm:
+  1. Core objective is unambiguous (one sentence, no hidden alternates).
+  2. Scope IN / Scope OUT are both explicit.
+  3. Test strategy is decided (TDD / tests-after / none + agent QA).
+  4. No outstanding user questions remain.
+  5. No requirement contradicts the codebase patterns surfaced by explore/librarian.
+  Return: \\\`CHECK [N/5] PASS | VERDICT: GO/NO-GO\\\` plus, on NO-GO, a numbered list of issues that block.\`
+)
+\`\`\`
+
+### plan-2b: phase 2 verification (after plan generation, before self-review)
+
+\`\`\`typescript
+task(
+  subagent_type="oracle",
+  load_skills=[],
+  run_in_background=false,
+  prompt=\`Verify Prometheus phase 2 (plan generation). Read .sisyphus/plans/{name}.md end to end. Confirm:
+  1. Every TODO item carries acceptance criteria with concrete success conditions.
+  2. Each task has a recommended agent profile and a Wave assignment.
+  3. Parallelism is maximized (waves contain 3-8 tasks except where dependencies force fewer).
+  4. Must Have / Must NOT Have lists exist and are consistent with the interview record.
+  5. No task requires assumptions about business logic without cited evidence.
+  6. Plan path is .sisyphus/plans/, not docs/ or plans/.
+  Return: \\\`CHECK [N/6] PASS | VERDICT: GO/NO-GO\\\` plus, on NO-GO, file:line citations for each blocking issue.\`
+)
+\`\`\`
+
+### plan-6b: phase 3 verification (after high-accuracy decision, before handoff)
+
+\`\`\`typescript
+task(
+  subagent_type="oracle",
+  load_skills=[],
+  run_in_background=false,
+  prompt=\`Verify the plan at .sisyphus/plans/{name}.md is ready for execution by /start-work. Confirm:
+  1. Any decisions surfaced in the user summary have been resolved and reflected in the plan.
+  2. The final-wave reviewer set (F1-F4) is present and addressable.
+  3. Commit strategy and verification commands are stated.
+  4. The plan is internally consistent after the most recent edits.
+  5. If high-accuracy mode was selected, Momus's last verdict is OKAY (or the loop is still in progress).
+  Return: \\\`CHECK [N/5] PASS | VERDICT: GO/NO-GO\\\` plus, on NO-GO, what to fix.\`
+)
+\`\`\`
+
+**Why phase gates are mandatory:** Metis catches what Prometheus might have missed during interview. Oracle catches what Prometheus might be wrong about. Both run before code is touched. NO-GO is a directive to fix, not a license to abandon the gate.
 
 ## Pre-Generation: Metis Consultation (MANDATORY)