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
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
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
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.

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.