docs: surface SP9-SP13 in README + endpoint reference

The README only documented up to SP8 even though SP9-SP13 (multi-payer
+ multi-NPI + SFTP stub, 277CA + Payer-Rejected lane, tamper-evident
audit log, optional SQLCipher encryption, paramiko SFTP wire-up) are
all merged into main.

This brings the README back in line with the codebase:

- Inbox section: bump lane count from four to five, add the
  payer_rejected lane (and its monotonic stamping contract).
- Add a Multi-Payer, Multi-NPI & Clearhouse section (SP9): the
  providers / payers / payer_configs / clearhouse tables, the
  config/payers.yaml loader, the new config + clearhouse endpoints.
- Add a 277CA Claim Acknowledgment section (SP10): parse-277ca +
  277ca-acks, the Payer-Rejected stamp semantics.
- Add a Tamper-Evident Audit Log section (SP11): hash-chained
  audit_log, the verify endpoint.
- Add an Encryption at Rest section (SP12): Keychain-stored
  SQLCipher key, transparent fallback to plain SQLite.
- Add an SFTP Wire-Up (paramiko) section (SP13): the production
  submit path and the file-naming template.
- Persistence section: link to the Encryption at Rest section.
- Roadmap: bump shipped sub-projects to 2-13, add a one-line
  pointer to the completeness review for the honest industry-gap
  accounting.
- Project layout: add api_helpers, db_crypto, audit_log, the new
  inbox_* modules, providers/payers/secrets, the new test files,
  and the config/ + docs/reviews/ + docs/superpowers/specs/ tree.
- backend/README: refresh the endpoint table to include the
  parse-999/parse-ta1/parse-277ca/eligibility/clearhouse/admin
  surface; point at the root README for the full route list.

README.md

@@ -130,10 +130,13 @@ backoff schedule on error is `1s → 2s → 4s → 8s → 16s → 30s` capped.
 
 ## Inbox
 
-`/inbox` is the working surface. Four lanes, dark by default (Ticker Tape
+`/inbox` is the working surface. Five lanes, dark by default (Ticker Tape
 aesthetic):
 
 - **Rejected** — claims whose 999 set-level response was R or E. Re-submit in bulk.
+- **Payer-rejected** — claims whose 277CA STC category is A4, A6, or A7 (the payer
+  accepted the file but denied the claim). Stamped at 277CA ingest time and never
+  overwritten by a looser later 277CA.
 - **Candidates** — remits whose CLP-claim-id didn't match exactly; each one shows its top scored claim. One-click manual match or dismiss.
 - **Unmatched** — claims still waiting for a remit, and remits with no candidates above the threshold.
 - **Done today** — terminal state transitions in the last 24 hours.
@@ -148,7 +151,7 @@ parses and rejects claims, the inbox reflects the new
 
 | Method | Path                                          | Notes                                                            |
 | ------ | --------------------------------------------- | ---------------------------------------------------------------- |
-| GET    | `/api/inbox/lanes`                            | All four lanes in one call.                                      |
+| GET    | `/api/inbox/lanes`                            | All five lanes in one call.                                      |
 | POST   | `/api/inbox/candidates/{remit_id}/match`      | Manual match. `409` if the claim state moved out from under us.  |
 | POST   | `/api/inbox/candidates/dismiss`               | `{pairs: [{claim_id, remit_id}]}`. Session-scoped.               |
 | POST   | `/api/inbox/rejected/resubmit`                | `{claim_ids: [...]}`. `200` with `conflicts` for non-rejected.   |
@@ -255,11 +258,139 @@ drawer surfaces a per-line "no 837 line matched" note.
 Tiers: **strong** (≥75, full opacity, Match enabled), **weak**
 (50–74, dimmed), **hidden** (<50, not surfaced).
 
+## Multi-Payer, Multi-NPI & Clearhouse
+
+The payer and provider identity that used to live as a single hard-coded
+`PayerConfig` dict in the backend is now data, not code. Three new tables
+plus a YAML file drive the entire configuration:
+
+- **`providers` table** — one row per billing-provider NPI (Montrose
+  `1881068062`, Delta `1851446637`, Salida `1467507269`). All three share
+  the same `TOC, Inc.` legal name, tax ID `721587149`, and taxonomy
+  `251E00000X`. Outbound 837 files pick the right `BillingProvider` by
+  NPI; `claim.party.npi` is now a foreign key into `providers`.
+- **`payers` table** — one row per payer (`CO_TXIX`, …) with its
+  receiver identity (NM1*40 / ISA08 / GS03).
+- **`payer_configs` join table** — one row per `(payer_id, transaction_type)`
+  pair. 837P and 835 can carry different `BHT06`, SBR defaults, and
+  allowed status codes per payer.
+- **`clearhouse` single-row config** — dzinesco's identity: TPID
+  `11525703`, submitter name, MT-clock file-naming block, SFTP block.
+- **`config/payers.yaml`** — the on-disk source for everything above,
+  schema-validated at boot against a Pydantic model. A typo or missing
+  field fails the boot with a precise error. The original in-code
+  `PAYER_FACTORIES` dict is kept as a fallback for ad-hoc testing.
+
+### Config + clearhouse endpoints
+
+| Method | Path                                          | Notes                                                            |
+| ------ | --------------------------------------------- | ---------------------------------------------------------------- |
+| GET    | `/api/clearhouse`                             | The `clearhouse` singleton (name, TPID, file/SFTP blocks).       |
+| POST   | `/api/clearhouse/submit`                      | Push a batch of generated 837 files via SFTP (see SFTP section). |
+| GET    | `/api/config/providers`                       | All providers.                                                   |
+| GET    | `/api/config/providers/{npi}`                 | One provider.                                                    |
+| GET    | `/api/config/payers`                          | All payers.                                                      |
+| GET    | `/api/config/payers/{payer_id}/configs`       | All `(payer_id, transaction_type)` configs for one payer.        |
+| POST   | `/api/admin/reload-config`                    | Re-read `config/payers.yaml` and refresh the in-process cache.   |
+
+## 277CA Claim Acknowledgment
+
+A 277CA (`005010X214`) is the per-claim acknowledgment CMS and
+Colorado Medicaid rely on: the file was syntactically valid *and* each
+named claim was accepted, pended, or rejected by the payer at the claim
+level. It is distinct from a 999 (file-level) and a TA1 (envelope-level).
+
+Cyclone ingests 277CA files the same way it ingests 999 / 835 — drop the
+file on the Upload page or `POST /api/parse-277ca` — and stamps every
+claim whose `STC` category is `A4`, `A6`, or `A7` with a non-null
+`payer_rejected_at` + `payer_rejected_reason` + originating 277CA row id.
+
+| Method | Path                       | Notes                                                            |
+| ------ | -------------------------- | ---------------------------------------------------------------- |
+| POST   | `/api/parse-277ca`         | Upload a 277CA, persist the parsed status rows.                  |
+| GET    | `/api/277ca-acks`          | List 277CA acks (filterable by date / payer).                    |
+| GET    | `/api/277ca-acks/{id}`     | One 277CA ack with its per-claim status rows + regenerated text. |
+
+The `payer_rejected` stamp is **monotonic**: a later 277CA with a looser
+status set cannot clear a previous rejection. The Payer-Rejected inbox
+lane surfaces every claim with a non-null `payer_rejected_at` — it is
+distinct from the 999 `Rejected` lane (envelope reject) and they can
+both be true for the same claim.
+
+## Tamper-Evident Audit Log
+
+The `audit_log` table is the canonical record of every state transition
+the system has ever observed — claim lifecycle, reconciliation
+decisions, config reloads, SFTP submissions, 277CA rejects. SP11 made
+it tamper-evident: every row carries a SHA-256 hash of
+`(prev_hash || row_payload)`, forming a chain back to a genesis row.
+Any `INSERT`, `UPDATE`, or `DELETE` that breaks the chain is detectable
+in a single walk.
+
+| Method | Path                              | Notes                                                          |
+| ------ | --------------------------------- | -------------------------------------------------------------- |
+| GET    | `/api/admin/audit-log`            | Paginated audit log (filterable by event type / actor / date). |
+| GET    | `/api/admin/audit-log/verify`     | Walk the chain; return the first broken link, or `{ok: true}`. |
+
+`verify_chain` is the integrity check that backs the audit promise —
+it is intentionally cheap (one indexed walk) and intentionally
+side-effect-free so a scheduler can run it on a cron and alert on any
+non-`{ok: true}` result. Chain verification is **not** access-gated
+beyond the same `127.0.0.1` bind the rest of the API uses; for a
+hostile multi-operator deployment, wrap the route in your reverse proxy.
+
+## Encryption at Rest
+
+When the macOS Keychain carries an entry at service `cyclone`, account
+`cyclone.db.key`, and the optional `sqlcipher3` Python package is
+installed, the SQLite file at `~/.local/share/cyclone/cyclone.db` is
+opened with SQLCipher (AES-256). The key is read from the Keychain
+once at process start, applied via a SQLAlchemy `connect` event so
+every connection — including migrations and tests — gets the same
+`PRAGMA key`. The key is never written to disk or to a Python global.
+
+When the Keychain entry is missing **or** `sqlcipher3` is not
+installed, the DB falls back to plain SQLite. The intent is a graceful
+default for developers and CI; the production posture is that every
+operator has created the Keychain entry on first run. See
+[docs/reference/co-medicaid.md §Keychain setup](docs/reference/co-medicaid.md)
+for the one-time setup recipe and the HIPAA Security Rule §164.312(a)(2)(iv)
+mapping.
+
+## SFTP Wire-Up (paramiko)
+
+The `clearhouse.submit` endpoint uses `paramiko` to push a batch of
+generated 837 files to the dzinesco SFTP server
+(`mft.gainwelltechnologies.com:22`, path
+`/CO XIX/PROD/coxix_prod_11525703/FromHPE`). The SFTP credential is
+fetched from the macOS Keychain at call time — never read from YAML,
+never logged, never written to disk. The wire-up honors the file-naming
+template stored in the `clearhouse` config:
+
+```
+outbound: {tpid}-{tx}-{ts_mt}-1of1.{ext}        e.g. 11525703-837P-20260620181814559-1of1.txt
+inbound:  TP{tpid}-{orig_tx}_M{tracking}-{ts}-1of1_{file_type}.x12
+```
+
+where `{ts_mt}` is a 17-digit `yyyymmddhhmmssSSS` Mountain Time stamp.
+Inbound filenames are routed by `<FileType>` and `<OrigTx>` to the
+matching parser (`999`, `TA1`, `271`, `277`, `277CA`, `835`).
+
+The `SftpClient` interface is the same one the SP9 stub used — the swap
+was a one-file change (`sftp_paramiko.py` replacing `sftp_stub.py`).
+`paramiko` is an optional dependency; the stub remains the default when
+the `paramiko` extras aren't installed so the test suite stays green on
+Linux dev boxes.
+
 ## Persistence
 
-Parsed batches, claims, remittances, matches, and activity events are
+Parsed batches, claims, remittances, matches, 277CA rejections,
-stored in a SQLite file at `~/.local/share/cyclone/cyclone.db` by
+hash-chained audit log entries, and SFTP submission history are stored
-default. The directory is auto-created on first run.
+in a SQLite file at `~/.local/share/cyclone/cyclone.db` by default.
+The directory is auto-created on first run. The DB is optionally
+encrypted with SQLCipher — see
+[Encryption at Rest](#encryption-at-rest) for the Keychain-driven
+setup.
 
 To use a different location, set `CYCLONE_DB_URL`:
 
@@ -285,11 +416,23 @@ backup API).
 ├── backend/
 │   ├── src/cyclone/
 │   │   ├── api.py             # FastAPI app, GET + parse routes, /api/{resource}/stream
+│   │   ├── api_helpers.py     # NDJSON / content-negotiation / live-tail helpers
 │   │   ├── pubsub.py          # in-process EventBus (drop-oldest, per-kind fan-out)
-│   │   ├── store.py           # InMemoryStore, mappers, publish-on-write
+│   │   ├── store.py           # CycloneStore, mappers, publish-on-write
+│   │   ├── db.py              # SQLAlchemy engine, session factory, ORM models
+│   │   ├── db_migrate.py      # PRAGMA user_version migration runner
+│   │   ├── db_crypto.py       # optional SQLCipher encryption at rest (SP12)
+│   │   ├── audit_log.py       # tamper-evident hash-chained audit_log (SP11)
+│   │   ├── inbox_lanes.py     # rejected / payer_rejected / candidates / unmatched / done_today
+│   │   ├── inbox_state.py     # 999 envelope reject → claim state transitions
+│   │   ├── inbox_state_277ca.py # 277CA STC A4/A6/A7 → payer_rejected stamp (SP10)
+│   │   ├── providers.py       # multi-NPI provider lookups (SP9)
+│   │   ├── payers.py          # payer / payer_config lookups (SP9)
+│   │   ├── secrets.py         # macOS Keychain-backed secret fetcher
+│   │   ├── reconcile.py       # pure-function 835→claim match + line-level match
 │   │   ├── __main__.py        # `python -m cyclone serve`
 │   │   ├── cli.py             # click CLI
-│   │   └── parsers/           # X12 tokenizer, models, validator, writers
+│   │   └── parsers/           # X12 tokenizer, models, validator, writers, 277CA, 999, TA1, 270, 271
 │   └── tests/
 │       ├── fixtures/          # co_medicaid_*.txt, minimal_*.txt
 │       ├── test_api.py        # parse-837/835 round-trip
@@ -298,29 +441,71 @@ backup API).
 │       ├── test_api_streaming.py
 │       ├── test_api_stream_live.py  # 3 live-tail endpoints + disconnect cleanup
 │       ├── test_pubsub.py     # EventBus + subscribe/unsubscribe
-│       └── test_api_parse_persists.py
+│       ├── test_api_parse_persists.py
+│       ├── test_db.py / test_db_crypto.py / test_db_migrate.py
+│       ├── test_audit_log.py
+│       ├── test_inbox_lanes.py / test_inbox_state.py
+│       ├── test_apply_277ca_rejections.py
+│       ├── test_sftp_stub.py / test_sftp_paramiko.py
+│       └── test_providers_seed.py / test_payer_config_loading.py
 ├── src/                       # React + Vite + TypeScript UI
 │   ├── components/
 │   │   ├── ui/                # Skeleton, EmptyState, ErrorState, FilterChips, Pagination, …
 │   │   └── TailStatusPill.tsx # live-tail status badge + reconnect button
-│   ├── pages/                 # Claims, Remittances, Providers, Activity, Upload
+│   ├── pages/                 # Claims, Remittances, Providers, Acks, Activity, Upload, Inbox, …
 │   ├── hooks/                 # useBatches, useClaims, useRemittances, useProviders, useActivity, useParse
 │   │                          # + useTailStream, useMergedTail (live tail)
-│   ├── lib/                   # api.ts (6 GET + parse837/parse835/health), format.ts, utils.ts
+│   ├── lib/                   # api.ts, format.ts, utils.ts
 │   │                          # + tail-stream.ts (NDJSON parser)
 │   ├── store/                 # zustand sample-data + parsed-batches store
 │   │                          # + tail-store.ts (FIFO-capped live tail slices)
 │   └── types/                 # shared TS types
+├── config/
+│   └── payers.yaml            # YAML-driven payer + clearhouse config (SP9)
 ├── docs/
-│   ├── reference/             # condensed 837P/835/X12/CO Medicaid notes
+│   ├── reference/             # condensed 837P/835/X12/CO Medicaid notes (incl. Keychain setup)
-│   └── superpowers/plans/     # implementation plan
+│   ├── reviews/               # post-SP completeness reviews
+│   ├── superpowers/plans/     # implementation plans
+│   └── superpowers/specs/     # design specs (incl. SP9-SP13)
 ├── tailwind.config.js         # shimmer, scan, row-flash keyframes
 └── package.json
 ```
 
 ## Roadmap
 
-Sub-projects 2 through 8 are **shipped**. Next up:
+Sub-projects 2 through 13 are **shipped**. See the [completeness
+review](docs/reviews/2026-06-20-cyclone-completeness-review.md) for
+the honest gap analysis against the industry definition of a HIPAA
+clearinghouse — the short version is that the local-only,
+single-operator, single-payer design contract is honored, and the
+items that would be needed to expand that contract (AS2/AS4, SNIP 1–7,
+HITRUST, 276/277 status, 278 referrals, COB) are intentionally out of
+scope.
+
+Shipped sub-projects (most recent first):
+
+- **Sub-project 13 (shipped) — SFTP wire-up.** `paramiko`-backed
+  `SftpClient` replaces the SP9 stub. The clearhouse.submit endpoint
+  actually pushes to
+  `mft.gainwelltechnologies.com:/CO XIX/PROD/coxix_prod_11525703/FromHPE`.
+  SFTP credentials are read from the macOS Keychain at call time.
+- **Sub-project 12 (shipped) — Encryption at rest.** Optional
+  SQLCipher AES-256 encryption of the SQLite file, with the key
+  fetched from the macOS Keychain. Falls back to plain SQLite when
+  the Keychain entry is missing or `sqlcipher3` isn't installed.
+- **Sub-project 11 (shipped) — Tamper-evident audit log.** Every
+  `audit_log` row carries a SHA-256 hash chained to the previous row;
+  a single walk via `GET /api/admin/audit-log/verify` detects any
+  break.
+- **Sub-project 10 (shipped) — 277CA + Payer-Rejected lane.** Inbound
+  277CA parser + a new Payer-Rejected inbox lane distinct from the
+  999-envelope Rejected lane. The rejection stamp is monotonic.
+- **Sub-project 9 (shipped) — Multi-payer, multi-NPI, SFTP stub.** The
+  in-code `PAYER_FACTORIES` dict is replaced by a `config/payers.yaml`
+  + 3 new DB tables (`providers`, `payers`, `payer_configs`) +
+  `clearhouse` singleton. Added a `POST /api/clearhouse/submit` stub
+  that writes to a local `staging_dir` — swapped for real `paramiko`
+  in SP13.
 
 - **Sub-project 8 (shipped) — Outbound 837P serializer.** Closes the
   resubmit loop: rejected claims can be regenerated back to an X12 837P
@@ -390,8 +575,9 @@ Sub-projects 2 through 8 are **shipped**. Next up:
     back-off ladder on errors is `1s → 2s → 4s → 8s → 16s → 30s`
     capped. See the "Live updates" section below for details.
 - **Sub-project 6 (shipped) — Inbox workflow automation.**
-  - **Ticker-Tape inbox (`/inbox`):** four lanes ordered by urgency —
+  - **Ticker-Tape inbox (`/inbox`):** five lanes ordered by urgency —
-    **Rejected** (claims whose 999 rejected them), **Candidates**
+    **Rejected** (claims whose 999 rejected them), **Payer-rejected**
+    (claims whose 277CA denied them — added in SP10), **Candidates**
     (remits that didn't auto-match a claim), **Unmatched** (claims
     still waiting for a remit), and **Done today** (terminal
     transitions in the last 24 hours). The page subscribes to the
@@ -428,6 +614,10 @@ Sub-projects 2 through 8 are **shipped**. Next up:
 - `GET /api/acks` — list ACKs.
 - `GET /api/acks/{id}` — ACK detail, including the regenerated
   `raw_999_text`.
+- `POST /api/parse-ta1` — parse an inbound TA1 envelope ACK and persist it.
+- `GET /api/ta1-acks` — list TA1 acks.
+- `GET /api/ta1-acks/{id}` — TA1 ack detail (envelope control segments
+  + the parser's accept/reject verdict).
 - `POST /api/eligibility/request` — build a 270 from JSON.
 - `POST /api/eligibility/parse-271` — ingest a 271 and return parsed
   coverage benefits.
@@ -459,9 +649,9 @@ ACKs and lets you download the regenerated 999 text.
 
 ### SP6 endpoints (inbox)
 
-- `GET /api/inbox/lanes` — all four lanes (rejected, candidates,
+- `GET /api/inbox/lanes` — all five lanes (rejected, payer_rejected,
-  unmatched, done_today) in a single round-trip, with row-level
+  candidates, unmatched, done_today) in a single round-trip, with
-  scoring and matched-remit context.
+  row-level scoring and matched-remit context.
 - `POST /api/inbox/candidates/{remit_id}/match` — manual match of a
   candidate remit to one of its scored claims; `409` if the claim
   state moved out from under us.
@@ -510,6 +700,58 @@ ACKs and lets you download the regenerated 999 text.
   Download** button in the Inbox rejected-lane BulkBar (N>1 modal
   prompt).
 
+### SP9 endpoints (multi-payer, multi-NPI, SFTP stub)
+
+- `GET /api/clearhouse` — the `clearhouse` singleton (name, TPID,
+  file-naming block, SFTP block).
+- `POST /api/clearhouse/submit` — push a batch of generated 837 files.
+  The SP9 implementation writes to a local `staging_dir`; the SP13
+  swap replaces the write with a real `paramiko` SFTP push without
+  changing the route shape.
+- `GET /api/config/providers` and `GET /api/config/providers/{npi}` —
+  list / fetch providers from the new `providers` table.
+- `GET /api/config/payers` and
+  `GET /api/config/payers/{payer_id}/configs` — list payers; for a
+  given payer, return the per-transaction-type `payer_configs` rows.
+- `POST /api/admin/reload-config` — re-read `config/payers.yaml` and
+  refresh the in-process cache without a server restart.
+
+### SP10 endpoints (277CA + Payer-Rejected lane)
+
+- `POST /api/parse-277ca` — upload a 277CA file; persist the parsed
+  `ClaimStatus` rows and stamp the matching claims with
+  `payer_rejected_at` (monotonic, never overwritten by `NULL`).
+- `GET /api/277ca-acks` — list 277CA acks.
+- `GET /api/277ca-acks/{id}` — one 277CA ack with its per-claim
+  `ClaimStatus` rows + regenerated text.
+- `GET /api/inbox/lanes` — the response now also carries a
+  `payer_rejected` lane populated from
+  `Claim.payer_rejected_at IS NOT NULL`.
+
+### SP11 endpoints (tamper-evident audit log)
+
+- `GET /api/admin/audit-log` — paginated audit log. Each row carries
+  `(id, prev_hash, row_hash, event_type, actor, payload_json,
+  created_at)` where `row_hash = sha256(prev_hash || canonical_json(payload))`.
+- `GET /api/admin/audit-log/verify` — walk the chain in insertion
+  order; return `{ok: true}` or the first `{id, expected, got}`
+  mismatch. The walk is O(n) with one indexed lookup per row.
+
+### SP12 (encryption at rest — no new routes)
+
+SP12 introduces no API routes. The `cyclone.db.key` Keychain entry +
+optional `sqlcipher3` dependency enable AES-256 encryption transparently
+on the next connection. See [Encryption at Rest](#encryption-at-rest)
+and [docs/reference/co-medicaid.md](docs/reference/co-medicaid.md) for
+the one-time setup recipe.
+
+### SP13 endpoints (paramiko SFTP)
+
+- `POST /api/clearhouse/submit` — same endpoint as SP9; the
+  implementation is now a real `paramiko` `SftpClient.write` to
+  `mft.gainwelltechnologies.com:/CO XIX/PROD/coxix_prod_11525703/FromHPE`.
+  SFTP credentials are fetched from the macOS Keychain at call time.
+
 ## License
 
 No license file yet; this is internal-use software. Add a `LICENSE` file

backend/README.md

@@ -79,10 +79,24 @@ python -m cyclone serve
 ### Endpoints
 
 | Method | Path                  | Purpose                                                            |
-| ------ | ---------------- | -------------------------------------------------- |
+| ------ | --------------------- | ------------------------------------------------------------------ |
 | GET    | `/api/health`         | Liveness probe: `{"status": "ok", "version": ...}`                 |
 | POST   | `/api/parse-837`      | Upload an X12 837P file, get parsed claims back                    |
 | POST   | `/api/parse-835`      | Upload an X12 835 ERA file, get parsed payouts back                |
+| POST   | `/api/parse-999`      | Upload an inbound 999 ACK and persist it                           |
+| POST   | `/api/parse-ta1`      | Upload an inbound TA1 envelope ACK and persist it                  |
+| POST   | `/api/parse-277ca`    | Upload a 277CA claim acknowledgment and stamp payer_rejected claims |
+| POST   | `/api/eligibility/request`   | Build a 270 from JSON (subscriber / provider / payer)        |
+| POST   | `/api/eligibility/parse-271` | Ingest a 271 and return structured `coverage_benefits`        |
+| GET    | `/api/clearhouse`     | The `clearhouse` singleton (SP9)                                   |
+| POST   | `/api/clearhouse/submit` | Push a batch of generated 837 files via SFTP (SP9 stub, SP13 real) |
+| POST   | `/api/admin/reload-config`  | Re-read `config/payers.yaml` and refresh the in-process cache |
+| GET    | `/api/admin/audit-log` | Paginated tamper-evident audit log (SP11)                          |
+| GET    | `/api/admin/audit-log/verify` | Walk the audit_log hash chain (SP11)                       |
+
+The full surface — claim / remittance / batch / inbox / stream
+endpoints, config lookups, and the 270/271 builder — is enumerated in
+the root [README](../README.md#multi-payer-multi-npi--clearhouse).
 
 `POST /api/parse-837` accepts `multipart/form-data` with a single `file`
 field. Optional query parameters: