sift/docs/implementer-log.md

# Implementer log

One row per task session that ends in a commit. Newest last.

| Task | Date | Status | Sessions | Gate | Deviations | Summary |
|---|---|---|---|---|---|---|
| p5a/01-kind-fetch | 2026-09-25 | done | resumed | gate: ok | none | Implemented Kind/`application/pdf` recognition, PDF body cap (100 MB) and deadline (120 s), and FetchIf with If-None-Match/If-Modified-Since via shared doFetch. Previous session could not pass TestFetchIf only because the given test held its mutex across the handler (deadlock); owner fixed the test. Session resumed after that fix — did not rewrite fetch code, only verified rules and ran gate. |
| p5a/02-pdftext | 2026-09-25 | done | 1 | gate: ok | none | Built the child-extraction package: `Extract` (reader.Open with ErrWrongPassword→ErrEncrypted, per-page recover, trailer /Info /Title, rule-3 UTF-16BE/Latin-1 decode), `outline.go` (/Dest and /GoTo /A dests, 10k-item and no-double-visit bounds, never-nil outline), `Runner` (re-exec'd child, env-isolated via empty env, 60 s deadline, 64 MiB output cap, 200 MiB stdin cap, stderr capped at 4 KiB, exit-code→error mapping, Doc parse plus ErrNoText), and the `sift pdftext` case in main.go. Removed the tools.go module pin; go.mod/go.sum/vendor/modules.txt confirmed unchanged. All 10 given tests pass under -race -count=3 including the deadline-kill test; make gate ok; given files byte-identical; `printf nope | bin/sift pdftext` exits 4. |
| p5a/03-dcache | 2026-09-25 | done | 1 | gate: ok | evict() tie-break | Added the pdf_doc/pdf_page tables, `PDFEntry`/`PDFKey`/`PutPDF`/`GetPDF`/`TouchPDF` (one-tx write deleting old pages first, page-ordered read, 304 touch moves only fetched_at), PDFH/PDFM counters, `Size()` including pdf_doc nbytes. One deviation: extended the eviction union with `pdf_doc` and added `rowid ASC` to the ORDER BY so same-second puts evict in insertion order (deterministic whole-document eviction); without it TestPDFEviction is order-dependent. Left Stats() signature unchanged for task 07. Given test byte-identical. |
| p5a/04-pdfpool | 2026-09-25 | done | 1 | gate: ok | none | Implemented the generic scheduler. `Pool` holds one mutex, a `jobs` map (key→in-flight job), a `callerJobs` map (caller→their job), and a FIFO `waiters` line. `Do` applies the six rules in order: join (counted in `Waiting`, no slot, allowed while the caller holds another job, `fn` may be nil), caller-busy, then slot/queue/refuse. A job's result is broadcast to every sharer via a `done` channel; results are not cached (key forgotten on finish). `fn` runs under `context.WithoutCancel` so the flight outlives a caller that leaves. Panic in `fn` is recovered into an error, freed the slot and caller. One implementation finding (not a plan deviation): queued jobs must not be counted in `Running()`, so `startLocked` only registers a job and a separate `takeSlotLocked`/`grant` increments the slot count — abandoning a queued starter (`abandon`) releases sharers without touching the slot. Given test byte-identical. |
| p5a/05-pdfdoc | 2026-09-25 | done | 1 | gate: ok | none | Implemented the render package with no I/O on a `*pdftext.Doc`. `Marker`/`Full` print each extracted page as `--- page N ---`, text trimmed, joined by a blank line. `Render` dispatches grep → page range → whole. Whole fits in OutCap runes, else a map: title (or `Untitled PDF`)/pages/`~tokens` line with `pages 1-E extracted` only when fewer extracted than `Pages`, a cuttable `## Outline` (two-space indent per level below 1, cut before the header/instruction), the instruction line, and whole leading pages within OutCap/4 (at least page 1, cut to fit). Range parses `a-b`/`a`/`a-`, wraps out-of-range in `ErrBadPages` with `pages out of range (1-E)`, clamps `b`, caps at 100 pages and OutCap runes, and notes the rest as `pages="k-b"`. Grep is RE2 with smart-case `(?i)` prefix, 200-byte cap, per-line matches with previous/next page context in `p. P-`/`p. P:` form, first 100 shown, total counted; RE2 keeps the `(a+)+$` test linear. Every length is in runes. Given test byte-identical; make gate ok. |
| p5a/06-api-pdf | 2026-09-26 | done | resumed | gate: ok (7 of 10 PDF tests; 3 are task 07's) | none | Served PDFs through `/v1/fetch` (clean) and `/v2/scrape`. Added `RetryAfter int` to `fetch.Error` and a `Retry-After` header line guarded by `> 0`. Added `PDFRunner`/`PDFPool`/`PDFTTL`/`PDFMaxQuestionChunks` Server fields (PDFPool built once via `sync.Once` only when nil, so the test's direct override is respected) and `pdfPoolOnce`. Routed `clean.Kind` in `doFetch`/`cleanFetched` (html/json/text switched, "other"→415, "pdf"→extractPDF); `doFetch`'s switch routes "text" explicitly so a PDF never runs `clean.Text` first. New `internal/api/pdf.go`: `DefaultPDFTTL`/`DefaultPDFMaxQuestionChunks` (task 07), `runner()`/`pool()` defaults, `extractPDF` (pool key `callerClass|SHA256`, two-value assert, `fmt.Errorf("pdf: bad result %T")`), `pdfError` (422 for the five pdftext errors + panic default, 503+RetryAfter 10 for ErrBusy, 429 for ErrCallerBusy), `renderPDF` (`pdfdoc.Render`, whole text or map). `doFetch` returns the 4th `doc *pdftext.Doc`; digest uses `pdfdoc.Full(doc)` (computed once) as content, clean uses `renderPDF.Content`, envelope `pdf` object has pages/title/outline/extracted/first/last/map/grep_hits/note, raw mode→400. Scrape markdown=`renderPDF.Content`, html="", `metadata.numPages`=doc.Pages. 7 of 10 given tests pass under -race -count=3; the 3 failures (`TestPDFPagesAndGrep`, `TestPDFCache`, `TestPDFQuestionTooLong`) are task 07 tests that reference fields not in this task, exactly as the task doc (lines 145, 157-158) predicts; nothing else fails. Given files byte-identical. |
| p5a/08-digest-cli-docs | 2026-09-26 | done | 1 | gate: ok | none | Added the page-cite sentence to the digest `systemPrompt` ("When the document has `--- page N ---` markers, cite the page of each fact as (p. N).") and set `PromptVersion = "3"`. Added the `sift_pdf_extract_total{outcome}`, `sift_pdf_extract_seconds`, `sift_pdf_pages_total`, `sift_pdf_pool_wait_seconds`, `sift_pdf_cache_hits_total` series to `internal/metrics` (`pdf.go` package) and wired `ObservePDF`/`ObservePDFWait`/`PDFCacheHit` into `internal/api/pdf.go` (`ObservePDF` once per call after `extractPDF`, outcome classified by `pdfOutcome` so raw text never becomes a label; `ObservePDFWait` only when the caller actually waited on `pool().Do`; `PDFCacheHit` on fresh hits and 304s). Refactored `cmd/sift/fetchcmd.go` into a `fetchOpts` struct with `parseFetchOpts` (returns `fetchOpts`, not `string, error`) and a `fetchBody(o fetchOpts) map[string]any` that does the digest/clean default and adds `pages`/`grep` only when set; `--pages`/`--grep` added to `fetchValueFlags`. Updated `skill/SKILL.md` (PDFs section; removed PDF mention from the 415 row). Unit: `nix/module.nix` `MemoryMax = "1G"` (one line). README: added a "PDF documents" section covering detection, limits (100 MB/120 s download, 60 s extraction, 2,000 pages), the child process, the 2-slot/4-wait/20 s pool, the 24 h conditional-GET cache, the answers, the task-06 errors table, and the metrics; noted the `go-pdfkit/extract` v0.3.0 engine chosen by the `docs/P5a.md` §3 bake-off. All tests pass under -race, make gate ok, three given files byte-identical, nix diff is one line. |
| p5b/01-splitpages-bm25 | 2026-09-26 | done | 1 | gate: ok | none | `splitpages.go`: `SplitPages` is Split's budget/line algorithm plus page awareness — a `--- page N ---` line sets the current page, and a chunk that starts after the first marker but not on a marker line is prefixed `--- page N (cont.) ---\n\n` for the page its first line belongs to (captured at chunk start, so a chunk that crosses a marker is still labelled with its starting page; the marker counts toward the chunk budget). No-marker text yields exactly Split's result, so `TestSplitKeepsPageMarkers` is untouched. `bm25.go`: `BM25` with k1=1.2/b=0.75, term counts via a local `docTerms` (same tokenization as `terms()`, >=2 chars), IDF `ln(1+(N-df+0.5)/(df+0.5))`, avgDL over all docs (guarded to 1 when the corpus is all-empty), one score per doc >= 0 with no query term scoring 0 and empty query/index scoring 0 everywhere. All digest tests pass under -race -count=3, make gate ok, two given files byte-identical. |
| p5b/02-retrieval | 2026-09-26 | done | 1 | gate: ok | none | Cached chunk embeddings + BM25-first retrieval. `digest.go`: `EmbedSyncMax=48`, `MaxDocChunks=5000`; `Result` gains `Retrieval string` and `Embedded int`; `selectText` now returns `(body, used, total, mode, embedded, err)` and `Run` sets both; `PutDigest` skips storing any `mode=="bm25"` answer (provisional, not cached). `retrieval.go`: `hybridOrBM25` — no cache, `len(chunks)<=48` embeds question+chunks inline and scores hybrid; `>48` scores BM25 and queues; cache present embeds the question and only the uncached chunks inline and scores hybrid on the union; both embed paths return hybrid, both bm25 paths return `bm25`. `background.go`: `bgWorker` with `bgOnce sync.Once` (creates the worker, never starts a goroutine) + `w.started` under `w.mu` (starts the goroutine once), dedup by `contentHash|callerClass`, full-queue drops the doc without marking seen so a later question re-queues, `acquireGate` retries once after 1 s on refusal, `WaitBackground` polls every 20 ms for true idle. `retrieval_test.go` copied byte-identical from the plan. All 12 digest tests pass under `-race -count=3`; `make gate` ok. |
| p5a/07-api-cache-pages | 2026-09-26 | done | 1 | gate: ok | none | Implemented the PDF document cache with revalidation in `doFetch`: `pdfFromCache` (miss / fresh within `PDFTTL` / stale → `FetchIf` with 304→`TouchPDF`+answer-fresh / 200→return response with ok=false and no second GET) and `storePDF` after `extractPDF` (`ContentHash=res.SHA256`, ETag/Last-Modified from headers, FetchedAt=now, Meta=JSON of `doc.Meta`, Pages=`doc.Text`). `pages`/`grep` passed into `pdfdoc.Options` in `renderPDF`; `ErrBadPages`/`ErrBadGrep`→400 with the error's own text, non-PDF→400 "pages and grep apply to PDFs only" before the doc block. Question limit in digest mode: `n=len(digest.Split(pdfdoc.Full(doc), ChunkTokens))`, `n>PDFMaxQuestionChunks`→422 "document too long for question (n chunks); use grep or pages" before any digest call. Envelope `cached` set true for cache answers via the synthetic cache res's empty body (`len(res.Body)==0`); the one `doFetch` change beyond the rule-1 call was reusing that 200 response instead of a second `Fetch`. Added `fmt` import to api.go. Given file byte-identical; make gate ok. |
| p5b/03-api | 2026-09-26 | done | 1 | gate: ok | none | The digest now answers long documents itself (task 02), so the API's refusal limit is only a safety cap: `DefaultPDFMaxQuestionChunks` 200→5000 in `internal/api/pdf.go` (the 422 message text unchanged, still "document too long for question (N chunks); use grep or pages"). In `v1fetch` (`internal/api/api.go`) the digest-meta map gains `"retrieval": dr.Retrieval` and `"embedded": dr.Embedded` next to `chunks_used`/`chunks_total`, only when the digest ran without a fallback. Copied the two given tests byte-identical from the plan — the replacement `pdf_test.go` is now the protected one and asserts `DefaultPDFMaxQuestionChunks == 5000`; `pdf_retrieval_test.go` asserts the first long-doc question returns `retrieval=bm25`, `embedded=0`. README PDF section: a long-doc question is answered first from BM25 (`retrieval: "bm25"`) while its chunks embed in the background and hybrid on later questions, plus the 5000-chunk cap. One sentence added to `skill/SKILL.md`. All api tests pass under `-race -count=3`; make gate ok; given files byte-identical. |
| p5c/01-extract-api | 2026-09-26 | done | 1 | gate: ok | none | `POST /v1/extract` answers a PDF posted in the body like `/v1/fetch` answers the same PDF by URL, nothing fetched. `internal/api/extract.go`: auth via `caller`; `io.ReadAll` of the body (a `*http.MaxBytesError`→413 "too large (>N MB)", empty→400); `clean.Kind` must be "pdf" else 415; query `pages`/`grep`/`question`/`mode` (digest when a question is set, else clean; other→400). Content-addressed cache: `hash="sha256:"+HashBody(body)`, `key=PDFKey("upload:"+hash, callerClass)`; a `GetPDF` hit rebuilds the doc via `pdfFromEntry` with `cached:true` + `PDFCacheHit` and no child (bypasses the TTL/revalidation that `pdfFromCache` does, so identical content is extracted once); a miss builds a synthetic `fetch.Resource{URL:"upload",...}` and runs `extractPDF`+`storePDF`. Bad pages/grep→400 via `writeFetchErr`, the chunk limit→the same 422 as `v1fetch`, extraction errors→`pdfError` via `writeFetchErr`. Envelope mirrors the PDF fetch path (`content`/`mode`/`untrusted`/`warnings`/`sizes`/`timings`/`pdf`/`digest`); `source` is `{"kind":"upload","hash","bytes","cached","fetched_at"}` with no `url` key; no Honcho context for uploads; one log line "extract" with caller/bytes/pdf_pages/mode/cached. `internal/api/api.go` scoped to the rule-1 changes: `DefaultPDFMaxUpload` const (100 MiB), `PDFMaxUpload int64` Server field, the `POST /v1/extract` route in `New`, and `ServeHTTP` (per-path upload cap instead of the 64 KiB JSON limit, and `/v1/extract` added to the `requestDeadline` switch). The `pdfMaxUpload()` field-or-default resolver lives in extract.go. Given test byte-identical; all api tests pass under `-race -count=3`; make gate ok. |
| p5c/02-extract-cli | 2026-09-26 | done | 1 | gate: ok | none | `sift extract <file.pdf>` uploads a local PDF to `/v1/extract` and prints the answer exactly as `sift fetch` does. `cmd/sift/extractcmd.go`: `extractOpts` + `parseExtractOpts` (reuses `splitAroundPositional` with `extractValueFlags` mode/pages/grep/question, one positional file, `--json`), `extractURL` builds `base+"/v1/extract"` with `url.Values` set only for the options that are set and `mode=digest` when a question is given and no mode — values are URL-encoded so a grep like `a b&c` survives round-trip; `extractMain` reuses `loadClient`, `stat`s the file and refuses >100 MiB before uploading (exit 3, matching the server's 413→exitFor), then `http.NewRequest` with the `*os.File` as the streaming body and `ContentLength` set (no second in-memory copy), `Content-Type: application/pdf` + bearer, and the same error/exitFor path as fetch; success prints `content` (or the `--json` envelope). `main.go`: `case "extract"` and one help line. README: extract line in the CLI block plus a sentence; SKILL.md: a PDF-on-disk bullet in the PDFs section. Given test byte-identical; all cmd/sift tests pass under `-race -count=3`; make gate ok; `bin/sift extract` prints the usage line. |

## P5a review (owner, 2026-09-26)

Checked: 8 task commits (`13365a2` … `7e78de6`), each with the `Co-Authored-By: ornith-1.5-35b-a3b`
trailer; every given file byte-identical to its plan copy; `internal/guard`, `internal/auth`,
`go.mod`, `go.sum`, `vendor/` untouched; `nix/module.nix` changed only in `MemoryMax`; `make gate`
ok; `go test -race -count=3 ./...` ok.

End-to-end with the real binary, the real guard, a real cache and dixie's 9B for digests, on
public PDFs: Attention (15 pp, whole text, 1.9 s), GPT-3 (75 pp, map, 2.6 s), NIST SP 800-63B,
the RP2040 datasheet (642 pp, 4.5 s), Karpathy's thesis (14.7 MB, 16 s including download).
`pages` and `grep` from the cache in about 1.5 ms; a `question` digest with correct page
citations (p. 1, 7, 8) in 11 s; `/v2/scrape` shape; `sift_pdf_*` metrics; no title or text in
the logs.

| # | Finding | Severity | Fault | Fix |
|---|---|---|---|---|
| 1 | **No outline for any LaTeX (hyperref) or Acrobat PDF** — every arXiv paper and the NIST PDF showed 0 items (qpdf: 22–120). Named destinations were skipped (task 02 said to skip them), `/Dest`/`/A`/titles were not resolved when indirect, and reader's `Dict.Get` returns `reader.Null{}` for a missing key, so the `/A` branch never ran. | high (feature absent on most papers) | task + model | owner: name-tree and `/Dests` lookup, `resolve` treats Null as absent, indirect titles; `pdftest` `NamedDests`; `TestOutlineNamedDestinations` (fails on the old code) |
| 2 | `pool()` read `PDFPool` outside its `sync.Once` — a data race on concurrent first use with no pool configured (the production default). | medium | model | owner: always through the Once; `TestDefaultPoolConcurrentFirstUse` (race on the old code) |
| 3 | Output over `MaxText` returned only at the deadline (the runner waited for stderr EOF while the child blocked on a full stdout pipe). | low | model | owner: check size first; `TestRunnerTooMuchTextFailsFast` (30 s on the old code) |
| 4 | Stale-cache revalidation ran outside `acquire`, so it was not counted against the per-caller/host limit. | low | task (said "before acquire") | owner |
| 5 | Fetch `Accept` lacked `application/pdf` (P5a §4). | low | task (not in task 01's rules) | owner |

Process: 1 owner test deadlock (task 01, 55 min), 1 oversized task (06, looped 3 h, split),
2 hangs from OpenCode 1.15 waiting on a piped stdin (driver fixed), 1 refusal-ending (task 01),
1 malformed tool call (task 04). Every task that ran to the gate passed it first time.