6krrt/docs/incidents.md

# Incidents: how this router has broken, and how to tell which one it is

Five times now, a change that looked local to the router has silently degraded
the agent depending on it. They share a shape worth naming: **none of them
announce themselves as router problems.** Four of the five presented as an
opaque client-side error — a connection refused, an "Unprocessable Content", an
"internal server error" — and diagnosing each meant knowing which log or table
to look in.

**#5 is the only one so far that destroyed data**, and the only one where
recovery depended on luck rather than design. Read it before running any
cleanup command in this repo.

This page exists so the next one takes minutes rather than hours. Start with the
symptom table, then read only the relevant section.

`opencode.json` points opencode's own model traffic at `http://127.0.0.1:8080/v1`,
so on this machine the router *is* the coding agent's inference supply. Breaking
it breaks the thing you would use to fix it. That is why these keep happening,
and why the diagnostics below are worth having to hand.

## Symptom → first check

| What you see | Likely | One-line check |
|---|---|---|
| `ConnectionError: Connection refused`, retrying | #1 killed by name/port | `systemctl --user status llm-router` — recently restarted, or inactive |
| `active (running)` but nothing answers | #2 shutdown hang | `curl -s localhost:8080/health` fails while systemd says active |
| Agent dies mid-task on an opaque 4xx | #3 candidate set empty | `sqlite3 router.db "select task_tier, required_context_tokens, rejected_reason from route_decisions where selected_model is null order by id desc limit 5;"` |
| "internal server error", dashboard blank | #4 config/db path | `journalctl --user -u llm-router --since '10 min ago' \| grep -c '" 500'` then `git diff config/config.yaml` |
| Prices/windows look wrong, nothing errors | catalog frozen | `sqlite3 router.db "select max(last_updated) from models;"` |
| 500s + `no such table`, venv/.env gone | #5 `git clean -fdx` | `ls -la router.db .env .venv` — a 0-byte db and a missing `.venv` is conclusive |

That last row is not an incident yet — it is the silent-staleness failure
described in the "Run as a service" section of `CLAUDE.md`. An unpolled catalog
fails **open**: it keeps routing on data that may be weeks old and every row
still reads `active`.

---

## #1 — Killed by name or port (2026-08-29)

**Symptom.** The dispatcher goes unreachable; the client retries against a
refused connection.

**Cause.** An agent ran `pkill -f "uvicorn dispatcher:app"` (also `.*dispatcher`,
also plain `"8080"`) to free the port for its own throwaway instance. When the
port came back 5s later — `Restart=always` resurrecting the supervised service —
it read that as "the kill didn't work" and escalated to `pkill -9`.

**Root cause was documentation, not code.** `AGENTS.md` offered a bare
`python -m uvicorn dispatcher:app --reload` as an equally-valid way to bring the
router up, with no warning that 8080 is normally already held. An agent
following that instruction and finding the port busy has no way to know the
right move is `systemctl --user restart`.

**Fixed** in `AGENTS.md`: ad hoc runs bind `--port 8081` explicitly, and the
section says outright never to send a kill signal to anything matched by name or
port. Full audit trail in
`plans/router-unreachable-signal-investigation.md` — the syscall-level extension
to `pidfd_send_signal` is what finally caught it, after `kill`/`tgkill` both came
back clean.

**Convention that came out of it:** 8080 is production, always. Throwaway
instances bind 8081. Never signal a process matched by name or port rather than
by a PID you started yourself.

## #2 — Bare SIGTERM hangs the process forever (2026-08-29)

**Symptom.** `systemctl --user status` reports `active (running)`; the socket is
closed and nothing answers. The process logged `Waiting for connections to
close` and never got past it.

**Cause.** SSE clients holding `/events/decisions` open (the TUI, the admin
dashboard) never disconnect, so uvicorn's graceful shutdown has nothing to wait
out. That alone is only slow. What made it permanent: systemd enforces
`TimeoutStopUSec` only when *it* is running the stop job, so a signal delivered
outside that path leaves the unit `active` forever — the main PID never exits,
so `Restart=` never fires either.

**Fixed** in `deploy/llm-router.service`: `--timeout-graceful-shutdown 5` caps
the drain regardless of who sends the signal. This also fixed ordinary restarts,
which were silently taking the full 10s-then-SIGKILL path for the same reason.

**Follow-up the fix exposed:** once the process could exit cleanly on SIGTERM,
`Restart=on-failure` excluded it from auto-restart — systemd assumes SIGTERM
means someone deliberately asked it to stop. Changed to `Restart=always`.
Deliberate `systemctl stop`/`restart` are still honoured; systemd tracks those
separately from the `Restart=` decision.

**Recovery:** `systemctl --user restart llm-router.service`. Since a hung
process was never in a tracked stop job, this issues a fresh cycle that systemd
*does* enforce the timeout on.

## #3 — Admin overrides collapsed the tier-3 context ceiling (2026-09-01)

**Symptom.** An agent failed mid-task with "Unprocessable Content". Surfaced
~19 hours after the cause.

**Cause.** Seven expensive models were deprecated through `/admin` — a
reasonable cost decision in isolation. The `models` table still read `active`
(the poller refreshes it every 2h), but `admin_model_overrides` overlays
`deprecated` and `_admin_deprecated_models` feeds that into routing's hard
filters. Effect on the maximum servable `required_context_tokens`:

| tier | before | during | eligible models |
|---|---|---|---|
| 1 | 782,324 | 782,324 | 6 |
| 2 | 782,324 | 782,324 | 5 |
| 3 | 782,324 | **94,196** | **1** |

Tier-3 traffic has an observed max of 268,168 tokens, so every tier-3 request
above 94k returned `422 No model satisfies the hard filters`. Nothing warned;
the portal reported the change as a plain success.

**The obvious check for this is wrong.** Warning when a higher tier's ceiling
sits below a lower tier's is a *theorem*, not a fault: `ceiling(T)` is the max
`effective_context_window` over models with `tier >= T`, and tier is a capability
floor, so the eligible set shrinks monotonically and
`ceiling(1) >= ceiling(2) >= ceiling(3)` holds for every catalog. Such a warning
fires always and means nothing. The real detector compares the ceiling against
**observed demand** — silent on all three tiers today, fires on the outage state.

**Fixed** by the `/metrics` ceiling warnings and an inline warning at the admin
availability toggle, so the cost of a deprecation is visible while looking at the
switch. See `plans/catalog-staleness-and-poller-failure-modes.md` §4.4.

**Recovery:** re-activate enough large-window rows to make the ladder
continuous. Today: 94,196 → 192,500 → 782,324.

## #4 — Tracked config pointed at a nonexistent database (2026-09-01)

**Symptom.** "Internal server error" in the client; the admin dashboard blank.

**Cause.** A QA step edited the **tracked** `config/config.yaml`, changing
`database.path` from `router.db` to `/tmp/router-qa/router.db`, created the
directory but never a database in it, and left the edit in the working tree.
`config/config.yaml` is the file the live systemd service reads.

```
1753  200
 201  500 Internal Server Error
sqlite3.OperationalError: unable to open database file

115 GET /metrics · 65 GET /health · 14 /admin/api/snapshot
 14 /admin/api/history · 7 POST /v1/chat/completions
```

Those 7 chat completions are real inference failing, not dashboard noise.

**Fixed** by reverting the one line and restarting. It was never committed.

**Rule:** never point `config/config.yaml` at test fixtures. To run against a
throwaway database, pass a different config file, monkeypatch
`cfg.database.path` in-process, or use a temp copy. If you must touch a file the
live service reads, restore it in the same step and verify
`curl -s localhost:8080/health` before moving on. A QA step that leaves
production broken has not passed.

## #5 — `git clean -fdx` destroyed the database, key and venv (2026-09-04)

**Symptom.** Router returned 500 on every request. Journal showed
`sqlite3.OperationalError: no such table: energy_observations` while systemd
reported the service `active`.

**Cause.** An agent ran `git clean -fdx` in the repo. The `-x` flag removes
**ignored** files as well as untracked ones, and everything this deployment
needs to run is ignored by design:

| lost | what it was |
|---|---|
| `router.db` | truncated to 0 bytes — 22,776 energy observations, 17,321 route decisions, 148 proficiency rows |
| `.env` | the NeuralWatt API key |
| `.venv` | the virtualenv the systemd unit's `ExecStart` runs from |
| `config/config.local.yaml` | the operator's electricity tariff |
| `node_modules` | |

This is worse than it looks from the command. `git clean -fd` is a reasonable
thing for an agent to run to get a clean tree. Adding `-x` turns it from
"discard my scratch files" into "delete the deployment", and nothing in the
repo warns you.

**Recovery was luck, not design.** There is no backup of `router.db` by policy.
What saved it was that the plan running at the time had made a QA copy at
`/tmp/qa-config-local-overlay-r2/` **25 seconds before the wipe**, and that
copy happened to include `.env`. Integrity check passed and the restore was
effectively lossless. Had that plan been a different one, the entire
measurement history of the project would be gone.

**Recovery steps, in order:**

```bash
# 1. find a surviving copy — QA/scratch dirs are the likely place
find /home/alee /tmp -name "router.db" -size +0
sqlite3 <candidate> "select count(*) from energy_observations;"
sqlite3 <candidate> "select integrity_check from pragma_integrity_check limit 1;"

# 2. restore data, key, overlay
cp -f <candidate> router.db
cp -f <candidate-dir>/.env .env && chmod 600 .env
#    config/config.local.yaml from your own copy

# 3. rebuild the venv (pinned, so this is deterministic)
python3 -m venv .venv && .venv/bin/pip install -r requirements.txt

# 4. restart and verify
systemctl --user restart llm-router.service
curl -s localhost:8080/health
```

**What actually limited the damage** was two unrelated decisions made minutes
earlier: the in-flight plan's 11 files had just been committed rather than left
uncommitted, and the operator's tariff had been parked *outside* the repo
instead of restored in place. Both were reactions to the same file being
clobbered repeatedly that day — the seventh time is what prompted moving it out
of reach.

**Known gap this leaves open.** `router.db` has no backup policy. It holds
every energy/cost observation, every routing decision, and all proficiency
scores — none of which can be rebuilt without re-running evals that cost real
money, and the historical observations cannot be rebuilt at all. A periodic
snapshot is cheap insurance and does not exist.

**Rules that came out of it:**

- **Never `git clean -x` in this repo.** Use targeted paths. If you need a
  clean tree, `git stash` preserves; `clean` destroys.
- **Never clean untracked files you did not create.** An untracked file in this
  tree is as likely to be operator data as build residue.
- Before any destructive git command, ask what is *ignored*, not just what is
  untracked. Here that list is the database, the API key and the runtime.


---

## The pattern

All five are defensible local decisions — free a port, stop a process, deprecate
an expensive model, point at a test database, clean the working tree — that
silently removed capability while the router kept reporting itself healthy.
Three of the five were caused by an agent working on the router, using the
router.

#5 breaks the pattern in one way worth noting: it did not degrade quietly, it
failed loudly and immediately. What it removed was not capability but *state* —
and state, unlike capability, does not come back when you fix the code.

The generalisable fix is the same each time: **compute the thing that is
actually true, and surface it where the operator is already looking.** That is
what the `/metrics` warnings and the inline admin warning are for, and it is the
reason the catalog-age and ceiling checks exist at all.