docs(claude): refresh "Where things stand" -- Series-4 live protocol and tooling

The orientation block was dated 2026-08-28 and predated every finding from the
Series-4 live-protocol work, which is exactly the content a fresh session needs
and cannot discover on its own.

Adds, at the top where it will actually be read:

  * The Series-4 live wire protocol is mapped end to end, with the three framing
    differences that break a Series III parser (no leading DLE, 0xC5/0x03 flags,
    uint16 length at payload[8:10]) and the note that the inbound call-home
    session is the only protocol unknown left.
  * That NO command has ever been originated against a unit by this project --
    every write was performed by THOR while we recorded.  Worth stating plainly
    so the next session does not casually break it.
  * That micromate/ is still codec-only with no live client, and that
    minimateplus.transport is protocol-agnostic and reusable when one is built.
  * The bench tooling, including why mm_frame_parse.py has to exist at all:
    S3FrameParser scans for DLE+STX and therefore cannot see Micromate
    responses.
  * The FTDI/CDC-ACM-only USB host constraint and the Sabrent/Benfei cable trap,
    since a PL2303 cable leaves a unit with no working modem port and the cables
    are indistinguishable by eye.

Corrects a stale operational claim: the v0.30.0 Series-4 backfill HAS now been
run on prod, so the ~3.3%-low geophone values are fixed and the job does not need
repeating.

Also generalises the "update the protocol reference" instruction from the single
Series III document to a table of all three, and adds bridges/ plus the two newer
docs to the project layout.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ru8Lg9HkkYvX9VWWo65SmL

CLAUDE.md

@@ -10,10 +10,38 @@ pair — lives in `../terra-view/docs/tmi-stack.md`, which is also loaded as
 
 ---
 
-## Where things stand (updated 2026-08-28)
+## Where things stand (updated 2026-09-26)
 
 Read this first when picking the project back up.
 
+- **The Series-4 LIVE wire protocol is reverse-engineered end to end
+  (2026-09-25).** `docs/micromate_protocol_reference.md` is the Series-4
+  Rosetta Stone, sibling to `instantel_protocol_reference.md`. **A Micromate
+  answers Series III command frames** — three framing differences: responses
+  have **no leading `DLE`** (a bare `STX`), `payload[1]` is `0xC5` (Blastware
+  firmware) or `0x03` (Thor firmware) rather than `0x10`, and the data length
+  is a **uint16 BE at `payload[8:10]`** (as a byte it under-reads `SUB 0x1A`
+  by 47x). Read path, event chain, setups, scheduler, monitoring control and
+  per-event delete are all mapped; **the inbound call-home session is the only
+  protocol unknown left.**
+  ⚠ **No command has ever been originated against a unit by this project.**
+  Every write was performed by THOR while we recorded. That line is worth
+  keeping.
+  ⚠ `micromate/` still has **no live client** — it is codec-only. The
+  `minimateplus/` stack (transport/framing/protocol/client) has no Series-4
+  counterpart yet. `minimateplus.transport` is protocol-agnostic and reusable.
+- **Bench tooling for device diagnosis (2026-09-25).** `bridges/mm_probe.py`
+  distinguishes the four faults THOR reports identically as "disconnected"
+  (refused / connect timeout / **connected but no reply** / replied) and names
+  what to try next. `bridges/mm_link.py` is a stand-in for a cellular modem
+  with a decoded log and fault injection. `scratch/mm_frame_parse.py` exists
+  because **`S3FrameParser` cannot see Micromate responses at all** — it scans
+  for `DLE+STX`, which never appears in Series-4 traffic.
+- **A Micromate's USB-A host port drives FTDI and CDC-ACM only** — no Prolific,
+  in either firmware line. TMI buys both Sabrent (FTDI) and Benfei (PL2303)
+  cables and they are indistinguishable by eye. A PL2303 cable leaves a unit
+  with **no working modem port at all**; identify by `lsusb` VID, `0403` vs
+  `067b`. This accounted for a unit that could not be deployed.
 - **Series-3 decode is verified per-sample at scale (v0.27.0).** The full DL2
   archive decodes **14,338 / 14,338** paired files exactly against their
   preserved Blastware ASCII exports — 1,249 waveform + 13,089 histogram, 45
@@ -92,6 +120,9 @@ Read this first when picking the project back up.
   **v0.27.0 does NOT owe prod a backfill** — verified: the partial-final-block
   fix changes 0 of the 10,215 histograms in the prod store (the 4 recovered
   files are archive-only and were never ingested).
+  ✅ **The v0.30.0 Series-4 backfill HAS been run on prod (2026-09-25).** Every
+  stored Series-4 geophone value was ~3.3% low until then; that is corrected and
+  the job does not need repeating.
 - **The "offset" hardware fault has its own journal** --
   `docs/offset_investigation.md`. **5 of 45 units (11%)**, and the fault is
   **persistent** — it stays until the geophone is serviced. Detect it with
@@ -103,7 +134,18 @@ Read this first when picking the project back up.
   `SUB 0x0E` (unimplemented), which may carry those very numbers.
 
 
-When new information about the protocol is discovered, please update the instantel_protocol_reference.md with the findings in addition to this document
+When new information about a protocol is discovered, record it in the matching
+reference **in addition to** this document:
+
+| series | document |
+|---|---|
+| Series III (MiniMate Plus / BlastMate) | `docs/instantel_protocol_reference.md` |
+| **Series IV (Micromate / THOR)** | **`docs/micromate_protocol_reference.md`** |
+| Thor IDF file format | `docs/idf_protocol_reference.md` |
+
+Both protocol references carry retractions in place rather than deleting what
+turned out to be wrong — that convention has already saved re-deriving the same
+mistakes twice, so keep it.
 
 ---
 
@@ -276,8 +318,15 @@ minimateplus/         ← Python client library (primary focus)
 
 sfm/server.py         ← FastAPI REST server exposing device data over HTTP
 seismo_lab.py         ← Tkinter GUI (Bridge + Analyzer + Console tabs)
+bridges/
+  mm_probe.py         ←   name the fault behind a dead unit (4 verdicts, read-only)
+  mm_link.py          ←   bench stand-in for a cellular modem, with fault injection
+  ach_mitm.py         ←   TCP relay for recording a Series-3 ACH session
+
 docs/
-  instantel_protocol_reference.md  ← reverse-engineered protocol spec ("the Rosetta Stone")
+  instantel_protocol_reference.md  ← Series III protocol spec ("the Rosetta Stone")
+  micromate_protocol_reference.md  ← Series IV protocol spec + THOR's measured behaviour
+  idf_protocol_reference.md        ← Thor IDF file format
 CHANGELOG.md          ← version history
 ```