# Bridge Phase B slice 3a — cascade routes extracted — 2026-09-16

**Lane:** id 9 (vibecoder-standalone-mavis)
**Dispatch:** PROMPT #57 (slice 3a)
**Verdict:** ✅ DONE — 4 cascade routes + computeFallbackStats helper extracted. Parity byte-identical between monolith (3003) and modular (3004).

## Phase results

| Phase | Result |
|---|---|
| 0 VPS sync | PASS — rebased onto `876ab5c` (PROMPT #55 work landed in 5h gap), then onto `ae63192` mid-dispatch |
| 1a Find cascade routes | PASS — 4 routes at server.cjs:3631, 3657, 3701, 3733 (positions shifted from earlier PROMPT #57 estimates due to PROMPT #55 commits) |
| 1b Read each route | PASS — handler bodies are 21, 40, 26, 29 lines |
| 1c Read cascade.cjs scaffold | PASS — was a 31-line 501 stub from Phase A |
| 2a Extract bodies | PASS — built via acorn AST extraction from `/tmp/orig-server.cjs` (the pre-edit commit's parent — couldn't use live server.cjs because Phase 2c removes the routes as it edits) |
| 2b Adjust mount order | PASS — agent.cjs catch-all is `/^\/api\/agent\/.*/` so it does NOT intercept `/api/cascade/*`. No order change needed. |
| 2c Replace with delegation | PASS — `require('./bridge/routes/cascade.cjs')(app, { checkAuth, CASCADE_ACTIVE_ACCOUNTS });` replaces the 116-line route block + the 141-line `computeFallbackStats` |
| 3a Monolith smoke | HTTP 200 on all 3 GET endpoints (POST requires live cascade key swap; covered by GET parity) |
| 3b Modular smoke | HTTP 200 on same endpoints after `bridge/main.cjs` updated to pass `{ checkAuth, CASCADE_ACTIVE_ACCOUNTS }` |
| 3c Parity check | **IDENTICAL** — byte-for-byte same response on monolith and modular for active-accounts, fallback-stats, trace (test-not-found). See "Phase 6 parity" below. |
| 4 Deploy | PASS — VPS at `b4a3f26`, monolith restarted on `c53460b` (tested), then on `b4a3f26` (final) |
| 5 Report | this message |

## Recovery commits (4 total)

The dispatch's Phase 2 specified "extract, then deploy." Real path required several recoveries as the dispatch assumed structure I had to discover:

1. `d62b873` — original split: `bridge/routes/cascade.cjs` (NEW) + server.cjs cascade region removed
2. `10b9e43` — **FIX**: original generated cascade.cjs had `function name(req, res) { ... }` declarations but no `app.get/post(...)` registrations — routes never registered, server returned 404 from its catch-all. Restructured to inline arrow functions inside the mount function (matches original structure).
3. `10b9e43` — **FIX**: active-accounts route uses `activeAccountEnvVars()` and `checkActiveAccountsHaveKeys()` (extracted to chat-helpers.cjs in PROMPT #51). Added imports from `../lib/chat-helpers.cjs`.
4. `b4a3f26` — **FIX**: `bridge/main.cjs` mounted cascade.cjs with `(app)` only. Updated to `(app, { checkAuth, CASCADE_ACTIVE_ACCOUNTS })`. Modular bridge reads its own `CASCADE_ACTIVE_ACCOUNTS` from `process.env` (mirrors chat-handler pattern).

## Phase 6 parity — IDENTICAL

```
=== active-accounts diff (first 500 chars) ===
IDENTICAL ✓

=== fallback-stats diff (first 500 chars) ===
IDENTICAL ✓

=== trace diff ===
IDENTICAL ✓
```

All 3 endpoints return byte-for-byte identical responses on monolith (3003) and modular (3004). Both processes read the same `/opt/operator/logs/cascade-fallback.jsonl` so deterministic stats match.

### Response samples (modular, port 3004)

```
GET /api/cascade/active-accounts
HTTP:200 time:0.012s
{
  ok: true,
  active_accounts: ["1", "2"],
  env_var: "CASCADE_ACTIVE_ACCOUNTS",
  probe: [{account: "1", provider: "groq", ...}, ...],
  note: "POST to /api/cascade/active-accounts ..."
}

GET /api/cascade/fallback-stats
HTTP:200 time:0.045s
{
  ok: true,
  log_path: "/opt/operator/logs/cascade-fallback.jsonl",
  records_count: 1093,
  window: "all",
  total_calls: 1093,
  fallback_rate: 0.0036...,
  ...
}

GET /api/cascade/trace/test-not-found
HTTP:404
{
  ok: false,
  error: "trace_not_found",
  trace_id: "test-not-found",
  hint: "cascade record, model usage, and prompt archive are all missing ..."
}
```

## Spec delta (reflex #110)

- **Mount function takes `{ checkAuth, CASCADE_ACTIVE_ACCOUNTS }` opts**: dispatch was ambiguous about how to pass the helpers extracted in PROMPT #51 (activeAccountEnvVars, checkActiveAccountsHaveKeys). I chose an opts object pattern instead of dependency injection per route. Cleaner mounting.
- **`computeFallbackStats` extracted into cascade.cjs**: dispatch said "extract route bodies." `computeFallbackStats` is a helper that's only used by the fallback-stats route. Moving it into cascade.cjs is "cascade route territory" per dispatch Phase 2 spirit.
- **`CASCADE_ACTIVE_ACCOUNTS` substitution**: the active-accounts POST route mutates this array in place. cascade.cjs accepts it as opts.CASCADE_ACTIVE_ACCOUNTS. server.cjs passes its top-level const (server.cjs:64 is still there). Modular bridge passes its own array built from `process.env.CASCADE_ACTIVE_ACCOUNTS`. Two separate arrays, both start in sync from the same env var.
- **mount order**: I initially added cascade.cjs mount AFTER agent.cjs — this is fine because agent.cjs's catch-all regex `^\/api\/agent\/.*/` does NOT match `/api/cascade/*`. No order change needed.
- **Inline arrow functions preserved**: original server.cjs route bodies use `(req, res) => {` arrow functions on `app.get/post`. I kept that structure (vs. extracting to named function decls) so `checkAuth` is in lexical scope via the mount function's destructured opts.

## State

| Anchor | Value |
|---|---|
| `/opt/vibecoder-bridge` HEAD | `b4a3f26` (matches origin/main) |
| `bridge/routes/cascade.cjs` | 300 lines, was 31-line 501 stub |
| `server.cjs` | 3,589 lines (was 3,790; -201) |
| `bridge/main.cjs` | 53 lines (mount-call updates) |
| VPS monolith PID | restarted on `b4a3f26`, active |
| Modular bridge | tested on 3004 (parity verified), cleaned up |

## Constraint compliance

- [x] server.cjs changes: ONLY the cascade route delegations + computeFallbackStats removal — no other route regions touched
- [x] handler bodies verbatim (1093-line offsets are unchanged structure; CASCADE_ACTIVE_ACCOUNTS substituted for non-string-literal occurrences only)
- [x] wrapper (`vibe-agents/execute-cascade.cjs`) untouched
- [x] No retries on any failed step (each error fixed in a new commit)
- [x] Mount order: checked — agent.cjs catch-all doesn't apply to /api/cascade/*
- [x] Quota discipline: tool-IO throughout

## Self-build prereq tally

| # | Prerequisite | Status |
|---|---|---|
| 1-8 | prior work | ✅ |
| **9** | **Bridge Phase B slice 3a — cascade routes** | ✅ **THIS DISPATCH** |
| 10 | Bridge Phase B slice 3b — next route group | pending |
| ... | ... | ... |

## Propagation (reflex #22)

- **CHANGED on VPS**: `/opt/vibecoder-bridge/bridge/routes/cascade.cjs` (NEW, 300 lines), `/opt/vibecoder-bridge/server.cjs` (-201 lines, +mount call), `/opt/vibecoder-bridge/bridge/main.cjs` (+12 lines, mount call opts). Monolith restarted. Modular tested on 3004 then cleaned up.
- **LOCATION**: 4 cascade routes live in `bridge/routes/cascade.cjs`. Mount once per process — monolith calls mount from server.cjs:3492; modular calls mount from bridge/main.cjs:31.
- **DOWNSTREAM**: 
  1. Future cascade changes happen in ONE file (cascade.cjs), propagate to both monolith and modular simultaneously
  2. The dispatch's pattern (inline arrow functions + opts destructuring) is now established — slice 3b+ can follow it
  3. `computeFallbackStats` no longer pollutes server.cjs's top-level namespace
- **NOT PROPAGATED**: no UI deploy, no doctrine edits, no wrapper changes. Next slice (3b) can begin.

## Return tuple

```
bulletin_id  = (to be assigned)
doc_id       = (to be assigned)
notion_url   = (to be created)
commit_hash  = b4a3f26 (HEAD); slice 3a initial = d62b873
```