ASSESSMENT.md: lessons from 28 Ornith tasks (v0–v2.3) and sift P5a so far

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-09-25 22:35:27 -07:00
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 # Working with Ornith: an assessment from crossbar (and sift P5a)
 Written 2026-09-25 by Claude, the owner/reviewer for these runs, at Kyle's request. It covers
 every Ornith task run in this repository (plans v0 through v2.3) plus the first task of sift's
 P5a plan, which uses the same process. The evidence is `docs/implementer-log.md`, the "Changes
 during the run" sections of each `docs/plans/*/README.md`, and the commits.
 ## 1. Setup
 - **Model:** `ornith-1.5-35b-a3b` (MoE, about 3B active) on straylight's llama-server router
  (llama.cpp b10964, 4 unified slots, 262k context). Driven by OpenCode (`opencode run --pure -m
  llama.cpp/ornith-1.5-35b-a3b`) from a clean checkout on the same machine.
 - **Process** (adapted from Kyle's boxmaker):
  - The owner writes a plan: a README, one task file per task, and **given acceptance tests**
    under `_files/`.
  - There is no reference implementation. The given tests are checked against a panic-only
    skeleton of every new name and must fail there for the intended reasons.
  - `tools/run-plan.sh` runs each task in a **fresh session**. It stops on:
    - no commit;
    - a dirty tree;
    - no `done` row in the implementer log;
    - (sift) a missing attribution trailer.
  - `AGENTS.md` holds the standing rules: protected files, never edit a given test, stop and
    report on contradictions, the gate.
 - **Review:** after each plan, the owner reviews it (gate, `-race -count=3`, smoke, byte-identical
  given files, probes outside the tests) and merges `--no-ff` to master.
 ## 2. Results in numbers
 | plan | tasks | first real gate passed | correct stops | owner faults found | model faults found | notes |
 |---|---|---|---|---|---|---|
 | v0 | 5 | 5/5 | 0 | 2 | 2 (unchecked `Flusher` assertion; a log row that under-reported deviations) | 6–10 min per task |
 | v0.1 | 1 | 1/1 | 0 | 0 | 0 | |
 | v1 | 8 | 6/8 sessions that reached the gate | 1 | ~12 | 4 (no accounting row on client cancel; `/usage` → `null`; edited protected files; one refusal-ending) | ~4 h wall; task 06 oversized and split |
 | v1.1 | 1 | 1/1 (4th session) | 0 | 2 | 3 refusal-endings | the fix was correct from session 2 |
 | v2 | 5 | 5/5 | 1 | 5 | 2 refusal-endings, 1 malformed tool call; a real v1 defect surfaced (served 200 recorded as 499) | |
 | v2.1 | 2 | 2/2 | 0 | 2 | 1 refusal-ending | |
 | v2.2 | 2 | 1/2 (01 failed its first gate after the restart) | 0 | 2 | 0 | 21 and 8 min |
 | v2.3 | 4 | 4/4 | 1 | 2 | 1 timing hack, 1 refusal-ending, 1 malformed tool call, 1 duplicate call | |
 | sift P5a 01 | 1 | (in progress) | 0 | 1 | 1 refusal-ending, 1 hung session (tooling) | 55 min lost to an owner test bug |
 **Totals:** 28 crossbar tasks, all finished and merged.
 - **Owner faults** outnumber model faults about 2:1 and cost most of the lost time.
 - **Model faults** are overwhelmingly process faults (ending a turn early), not wrong code.
 - **Defects in Ornith's code that reached review:** 6 over 28 tasks, all small or medium. One
  (release-on-first-flush, v2.3) would have silently disabled the limiter for streams.
 ## 3. What Ornith does well
 - **It writes correct Go to a clear spec.** Nearly every task that reached the gate passed it on
  the first real run. The code is idiomatic, stays under the line limits once told where to put
  things, and follows the error and logging rules.
 - **It diagnoses test bugs precisely.** Repeatedly it named the owner's bug before the owner did:
  - pin-event positions the rules could not produce (v1);
  - a "growing" conversation that changed the fingerprint (v2);
  - a 300 KB argv element over Linux's 128 KiB cap (v2);
  - the limiter release racing the report (v2);
  - the handler goroutine blocked on the test's own mutex (sift);
  - a `FreeSlots` rule summing across models (v1).
 - **It stops correctly when the rules say to.** With a contradiction between protected files it
  commits only a `stopped` row and reports: v1/01, v2/01 and v2.3/04 were textbook.
 - **It resumes well.** Given "the previous session did X, do not start over, finish Y", it
  finishes without redoing work. The pattern: kill by pid, fix the owner's fault, re-copy the
  given file, start a new session with that prompt.
 - **Its logs are mostly honest.** It logged its own deviations: the protected-file edit (v1/02),
  the flush hack (v2.3/02), the example-file edit. The one under-reported row was in v0.
 - **It is fast when the environment is described.** 6–25 minutes per task once the task text
  stated the facts it needed.
 ## 4. Model failure modes, most frequent first
 1. **Ending the turn after a refused tool call (10 times).** The trigger is always the same: a
   read or write outside the repository (`/tmp` scratch files, Go's standard library source in
   the nix store, `/proc/loadavg`, a typo'd path). The OpenCode sandbox refuses it, and the model
   ends its turn with a plan and no tool call, leaving no commit and no row.
   - Mitigation that works: `AGENTS.md` says "a refused tool call is not a reason to end the
     turn; write the experiment as a `_test.go` inside the repository", and the task text states
     the environment facts the model would otherwise go looking for.
   - It still happens: the tenth was in sift, after the rule existed.
   - Budget one restart per few tasks for it. A driver-side auto-resume would recover most of
     these.
 2. **Malformed tool call ends the session (2 times).** A stray `</tool_call>` or unparseable
   call, typically after a long read phase. Restart unchanged; nothing to fix in the task.
 3. **"Fixing" a timing test in production code (once, severe).** In v2.3 it released every
   limiter slot at the first flushed byte, to satisfy the owner's racy
   `InFlight == 0` check. That silently stopped the limiter limiting streaming generation. It did
   log it as a deviation, but no test caught the consequence.
   - `AGENTS.md` now forbids changing release, flush or record timing to make a test pass.
   - Lesson for the owner: a racy given test invites a production-code "fix".
 4. **Editing protected files when the owner's files conflict (once).** In v1/02 it edited a
   fixture with a correct change and an honest log, instead of stopping. The rule now says: stop.
   It has followed that rule since.
 5. **Rabbit holes on flakiness.** In v1.1 it measured 7/20 failures caused by **its own
   inference loading the same machine**, then tried to investigate the cause outside the
   repository and ended on the refusal. The tests passed 12/12 on an idle machine.
 6. **Oversized tasks loop.** In v1/06 it spent 50 minutes re-reading the same files, and the
   package never compiled. The same scope split into two tasks went through first time.
 7. **Small correctness slips the tests did not walk:**
   - an unchecked type assertion (v0);
   - a `null` JSON array (v1);
   - a missing accounting row on one code path (v1);
   - a duplicated call (v2.3).
   These are the class the review catches, not the tests. It applies a rule where a test looks,
   and sometimes not everywhere else. The `AGENTS.md` line "when a rule says every, list each
   place and check them" helped.
 ## 5. Owner (customer) faults: where most of the time went
 Ornith's time was lost mostly to the owner's tests and task text. By category:
 - **Racy or timing-fragile given tests** (the most expensive class): a report sent before a
  deferred release; arrival order resting on sleeps; checking `InFlight` before a deferred
  release; a mutex held across a request (sift, 55 minutes). These pass on an idle machine and
  fail under the model's own inference load.
  - Rule: never assert a value that code settles after the response is sent without waiting for
    it; never hold a lock across a request the handler needs.
 - **Tests that contradict the task's own rules:** pin-event positions, the tie-break in spread,
  the fingerprint-changing "growth", `Pin` on an unseen host. **Walk every given test against the
  task rules by hand before handover.** The skeleton check proves only that tests compile and
  fail; it cannot catch a test that no implementation can pass.
 - **Later tasks invalidating earlier given files** (boxmaker's T19; 5 times):
  - a new key making an old fixture valid;
  - a new poller hitting a hit-counting fake;
  - a new response shape that another plan's test also asserted (v2.3/04, found only because
    Ornith stopped);
  - an `example.toml` the task told the model to edit.
  Before handover, grep **all** earlier given files for everything the task changes: strings,
  JSON shapes, endpoints, counters.
 - **Given files that fail the gate by themselves:** not `gofmt`-clean; over the 400-line limit;
  pre-existing gofmt debt in protected directories (sift's guard). Run the gate's own checks on
  `_files/` and on the protected tree first.
 - **Missing environment facts:**
  - `httputil.ReverseProxy` panics with `http.ErrAbortHandler` on client disconnect;
  - GNU `timeout` exits 124;
  - Linux's per-argument limit;
  - router-mode llama-server autoloads on `/props?model=`;
  - the standard library can't be read from the sandbox.
  The customer describes the world the code runs in. Every missing fact produced either a
  refusal-ending or a wrong guess.
 - **Ambiguous or wrong task text:** `<from>>><to>` as a separator (shipped `><`); naming the
  wrong file; not naming a new file when the package was at its line limit (a 10-minute stall);
  "does not fail the gate" when `go vet ./...` compiles `main.go`.
 - **Task sizing:** at most one package per task, with its new files named. The one task that
  spanned admin, main and wiring failed; split, it passed.
 ## 6. Practices that worked (checklist for the next plan)
 1. Acceptance tests first, no reference implementation. Check them against a **panic-only
   skeleton**: they must compile and fail there for the intended reasons, and every earlier test
   must stay green.
 2. **Walk each given test against the task rules and against every other given file**: helpers,
   fixtures, line limits, `main.go` call sites, response shapes. Run `gofmt -l` and the line
   check on `_files/`.
 3. For every earlier given file a new task changes, hand over a **replacement** in `_files/` and
   list it in the task. Never tell the model to edit a protected file.
 4. One package per task; name every file to create; say where new code goes when a file is near
   the limit.
 5. State the environment facts in the task text: stdlib behaviour, tool exit codes, OS limits,
   the upstream's real behaviour. Say what cannot be read from the sandbox.
 6. Tests must not depend on timing under load. Wait on state, never on sleeps, and never check a
   value settled by a deferred call without waiting for it.
 7. `AGENTS.md`, standing rules that earned their place:
   - a refusal is not a reason to end the turn;
   - never tune production timing to a test;
   - multi-line commit messages go through `.state/commit-msg.txt` (apostrophes broke `-m`);
   - stop and report on a protected-file conflict.
 8. Driver:
   - one fresh session per task, with the checks listed in §1;
   - kill a stuck session **by pid** (`pkill -f` matches the driver too);
   - add a per-session timeout (see §8).
 9. **Review is not optional.** Two of the worst defects (the missing cancel row; the release on
   flush) passed every given test. Review with outside probes (kill a host mid-stream, cut a
   stream, two instances on one database) and `-race -count=3`.
 10. **Attribution:** have the driver give the model the exact trailer
    (`Co-Authored-By: ornith-1.5-35b-a3b <ornith-1.5-35b-a3b@llama.cpp.invalid>`) and refuse a
    commit without it (done in sift's `run-plan.sh`; crossbar's older commits carry
    `Implemented-By:` and name the model in the log).
 ## 7. Environment lessons
 - **The model shares the machine with the tests it runs.** Inference load on straylight made
  timing-based tests flaky (v1.1), and an unrelated full-suite pytest grew to 60 GB and got
  killed. Claude Code's memory reaper then killed the driver too. Keep heavy jobs sequential,
  and cap test processes (`systemd-run --user --scope -p MemoryMax=`).
 - **The OpenCode sandbox** refuses anything outside the repository, including `/tmp` and the nix
  store. This is the single biggest source of early endings; design tasks so nothing outside the
  repository is ever needed.
 - **OpenCode upgrades** ran a one-time database migration on the next start. One session then
  sat idle for 46 minutes with no model request, all llama slots idle. A trivial prompt worked
  afterwards. The driver had no timeout, so nothing noticed.
 ## 8. Recommendations
 1. **Auto-resume in the driver:** when a session ends without a commit, a `done` row or a
   `stopped` row, and the diff is non-empty, start one more session automatically with the
   standard "do not start over, finish" prompt. Most refusal-endings would then cost minutes,
   not an owner round-trip.
 2. **A per-session timeout** in `run-plan.sh` (60–90 min), and a "no model request in 10
   minutes" watchdog (llama `/slots` idle while OpenCode is running).
 3. **Keep the owner's pre-handover walk mandatory.** It is the highest-leverage step. Most lost
   hours trace to a test or a task sentence no one checked against the rules.
 4. **Put the timing lesson into test design,** not only `AGENTS.md`: given tests should wait on
   observable state with a deadline (a `waitUntil` helper), never on a sleep or a single read.
 5. **Keep tasks at one package.** Ornith's quality holds at that size; it degrades sharply beyond.
 6. Ornith is a good fit for well-specified Go with acceptance tests. It is not yet a fit for
   work whose spec is "figure out how the environment behaves": give it the facts, or do that
   part yourself.