dcache: batch job and target tables with a sliding lease, sweep and byte budget

Add the batch job store to internal/dcache (storage only; no HTTP, no worker).
New internal/dcache/batch.go holds the BatchJob/BatchTarget types and all
accessors; Open gains the batch_job/batch_target tables and indices, and DB
gains BatchH/BatchM counters.

Sliding lease: writes (UpdateBatchTarget, SetBatchJobStatus, TouchBatchJob,
MarkInFlightFailed) bump the job lease to now; reads never write. BatchJobByIDem
returns the newest (caller, idem_key) job with lease+ttl>now and status
queued/running/done/partial. UpdateBatchTarget counts targets_done exactly once
per target entering done/failed and adds len(result) to nbytes. SweepBatch
removes by lease; EvictBatchOldest evicts whole non-live jobs oldest-lease-first;
MarkInFlightFailed reconciles in-flight jobs on restart. Batch nbytes are kept out
of Size() and the content evict union.

Co-Authored-By: ornith-1.5-35b-a3b <ornith-1.5-35b-a3b@llama.cpp.invalid>

docs/implementer-log.md

@@ -17,6 +17,7 @@ One row per task session that ends in a commit. Newest last.
 | 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. |
+| p6/01-batchstore | 2026-09-26 | done | 1 | gate: ok | none | Storage-only batch store in `internal/dcache` (new `batch.go`; schema added to `Open`; `BatchH`/`BatchM` counters added to `DB`). `CreateBatchJob` stores as given. Reads never write the lease: `BatchJob`, `BatchTargets` and the counts are pure, so exact lease values hold after a read. `BatchJobByIDem` returns the newest `(caller,idemKey)` job with `lease+ttl>now` and status queued/running/done/partial; failed/cancelled never reused. `PutBatchTargets` inserts in order; `BatchTargets` returns idx order with NULLs as nil pointers. `UpdateBatchTarget` bumps lease to `now`, increments `targets_done` exactly once per target entering done/failed (previous-status check prevents re-write double-count), and adds `len(result)` to `nbytes` when a result is written — all in one tx. `SetBatchJobStatus`/`TouchBatchJob` set lease; `SweepBatch` deletes by `lease+ttl<=now` with its targets and returns the job count; `EvictBatchOldest` evicts whole non-live jobs oldest-lease-first (never a queued/running one) until `BatchNbytes()<=maxBytes`; `MarkInFlightFailed` fails queued/running on restart; `BatchNbytes` sums job nbytes, kept out of `Size()`. Accessors return `(v,bool)`/`error`, count misses in `BatchM`, reuse `ClassFleet`/`ClassRestricted`. A first pass failed `TestBatchIDemLookup` because I forgot `.Scan(&id)` on the `QueryRow` (the un-scanned `*sql.Row` was always non-nil, so the method always missed); fixed and verified. All dcache tests pass under `-race -count=3`; make gate ok; given file byte-identical. |
 
 ## P5a review (owner, 2026-09-26)