fix(conductor): load Tier 2 role doc in startup, add Tier 3 failure protocol

- Add step 1: read mma-tier2-tech-lead.md before any track work
- Add explicit stop rule when Tier 3 delegation fails (credit/API error)
  Tier 2 must NOT silently absorb Tier 3 work as a fallback

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.claude/commands/conductor-implement.md

@@ -9,10 +9,11 @@ You maintain PERSISTENT context throughout the track — do NOT lose state.
 
 ## Startup
 
-1. Read `conductor/workflow.md` for the full task lifecycle protocol
-2. Read `conductor/tech-stack.md` for technology constraints
-3. Read the target track's `spec.md` and `plan.md`
-4. Identify the current task: first `[ ]` or `[~]` in `plan.md`
+1. Read `.claude/commands/mma-tier2-tech-lead.md` — load your role definition and hard rules FIRST
+2. Read `conductor/workflow.md` for the full task lifecycle protocol
+3. Read `conductor/tech-stack.md` for technology constraints
+4. Read the target track's `spec.md` and `plan.md`
+5. Identify the current task: first `[ ]` or `[~]` in `plan.md`
 
 If no track name is provided, run `/conductor-status` first and ask which track to implement.
 
@@ -81,7 +82,13 @@ Commit: `conductor(plan): Mark task '{TASK_NAME}' as complete`
 - If phase complete: run `/conductor-verify`
 
 ## Error Handling
-If tests fail with large output, delegate to Tier 4 QA:
+
+### Tier 3 delegation fails (credit limit, API error, timeout)
+**STOP** — do NOT implement inline as a fallback. Ask the user:
+> "Tier 3 Worker is unavailable ({reason}). Should I continue with a different provider, or wait?"
+Never silently absorb Tier 3 work into Tier 2 context.
+
+### Tests fail with large output — delegate to Tier 4 QA:
 ```powershell
 uv run python scripts\claude_mma_exec.py --role tier4-qa "Analyze this test failure: {ERROR_SUMMARY}. Test file: {TEST_FILE}"
 ```