api: /v1/batch — submit, status summary, one result, cancel

The HTTP surface over s.Batch. New internal/api/batch.go: batchSubmit (POST)
decodes {"targets":[{url,mode,question,pages,grep,jq,context,recover}]} flat as
/v1/fetch does, 400 "invalid batch" on bad json / empty list / empty url / bad
mode, then PreCheck per target -> 422 "blocked: target <idx>: <reason>" with no
job, then Submit mapping ErrTooManyTargets->422, ErrCallerBusy->429 Retry-After
30, ErrBusy->429 Retry-After 60, ErrNoTargets->400, and 202
{success,job_id,status,targets,reused}. batchStatus (GET), batchResult
(GET {id}/{idx}) and batchCancel (DELETE) share ownership: unknown or not
c.Name -> 404, never 403; status is a summary (no inline results unless
?results=1), idx validated 0..targets_total-1 else 404, cancel of a terminal
job -> 409 else 200 {success,status:cancelled}. api.go scoped to rule 2:
batchMaxBody (256 KiB), the four routes in New, and ServeHTTP applying the
per-path cap once and collapsing every batch path to a fixed metrics label so a
job id never becomes a label. Each handler logs one batch line, never a URL,
hostname or idem_key.

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

docs/implementer-log.md

@@ -23,6 +23,7 @@ One row per task session that ends in a commit. Newest last.
 | p6/04-metrics | 2026-09-26 | done | 1 | gate: ok | none | Batch series in new internal/metrics/batch.go, registered in New: `BatchJobsTotal`/`BatchTargetsTotal` CounterVecs (label "outcome", any value outside the known set folded to "other" via `batchJobOutcomes`/`batchTargetOutcomes` maps so a raw string never becomes a label), `BatchQueueDepth`/`BatchTargetsInflight` gauges, and `BatchJobSeconds`/`BatchTargetSeconds` histograms (durationBuckets) plus `BatchResultBytes` (1K,4K,16K,64K,256K,1M). Nil-receiver-safe `Observe…`/`Set…` methods mirroring ObservePDF/ObserveDigest. Series served through the existing /metrics handler; no new endpoint, no Snapshot change. Given test byte-identical; metrics tests pass under -race -count=3; make gate ok. |
 | p6/05-fetchtarget | 2026-09-26 | done | 1 | gate: ok | none | Extracted v1fetch's per-target pipeline into new `internal/api/target.go`: `fetchTarget(ctx, c, t batch.Target) (batch.Result, error)`. Body moved unchanged in order — question truncation to 500 runes, mode default/check, wantCtx, doFetch, recover path, PDF branch (render, pages/grep errors, question-chunk limit), clean/raw branch, digest, context search, the fetch log line, and the envelope. `content` is returned as `Result.Content`; every other envelope key (`mode`,`untrusted`,`source`,`warnings`,`sizes`,`timings`, and `pdf`/`digest`/`context` when present) goes in `Result.Meta`, never content. `v1fetch` keeps reqN/caller/decode/400, builds a `batch.Target` (`URL` + `Mode`/`Question`/`Pages`/`Grep`/`JQ`/`Context`/`Recover` into `Options`), calls `fetchTarget`, `writeFetchErr` on error and `writeJSON(w,200,env)` on success where `env` is a fresh copy of `Meta` plus `"content"` (a copy, so `len(env)==len(Meta)+1` holds and Meta is not mutated). The two `writeErr` failures become `*fetch.Error` with the same status/msg/hint: 400 "invalid url" (bad mode), 400 "raw mode does not apply to PDFs". `doFetch` takes `context.Context` instead of `*http.Request` (its three `r.Context()` → `ctx`); `scrape` passes `r.Context()`. Removed now-unused `fmt`/`unicode/utf8`/`recover` imports, added `batch`. All api tests pass under -race -count=3; make gate ok; given test byte-identical. |
 | p6/06-batch-wiring | 2026-09-26 | done | 1 | gate: ok | none | New `internal/api/batch.go`: `NewBatchRunner` overwrites `cfg.Hooks` so Job→ObserveBatchJob, Target→ObserveBatchTarget(batchOutcome)+ObserveBatchTargetSeconds (+ObserveBatchResultBytes only when err==nil), and JobSeconds/Depth/Inflight→the matching `s.Prom` methods; the runner's FetchFunc is `batchFetch`, which tags ctx with an unexported `batchCtxKey`, runs under `requestDeadline`, and maps fetchTarget's errors (a *fetch.Error 429/503 → `fmt.Errorf("%s: %w", fe.Msg, batch.ErrRetryLater)` so the runner retries; any other *fetch.Error → TargetError with 502 rewritten to 500 "internal error" and `s.blockN.Add(1)` for 403; anything else → TargetError 500 logged Error with `s.logErr`). `batchOutcome` classifies nil→ok, ErrRetryLater-wrapped→busy, then by TargetError.Status (403 blocked, 429 busy, 504 timeout, 415 unsupported, 422 whose Msg starts "document too long"→too_long, other 4xx→upstream_4xx, 5xx→upstream_5xx, any other error→upstream_5xx). Added `Batch *batch.Runner` Server field (nil → the /v1/batch endpoints answer 503 "batch disabled"). `pdf.go` extractPDF charges the PDF pool to `c.Name+"/batch"` when the ctx carries the batch mark, single-flight key unchanged so a batch and an interactive extract of the same PDF still share one child; the only new log line carries caller and host="-" (never a URL/host). All api tests pass under -race -count=3; make gate ok; given file byte-identical. |
+| p6/07-api-endpoints | 2026-09-26 | done | 1 | gate: ok | none | The four /v1/batch handlers in new `internal/api/batch.go`: `batchSubmit` (POST) decodes `{"targets":[{url,mode,question,pages,grep,jq,context,recover}]}` flat like `/v1/fetch`, 400 "invalid batch" on bad json/empty list/empty url/bad mode (only empty,clean,raw,digest), then `PreCheck` per target → 422 "blocked: target <idx>: <reason>" with no job, then `Submit` mapping ErrTooManyTargets→422 "too many targets (max 32)", ErrCallerBusy→429+Retry-After 30, ErrBusy→429+Retry-After 60, ErrNoTargets→400, and 202 {success,job_id,status,targets,reused} (status "queued" new, current status reused). `batchStatus` (GET) and `batchResult` (GET {id}/{idx}) and `batchCancel` (DELETE) share `ownership` (unknown or not `c.Name` → 404, never 403; nil batch → 503); status is a summary with no results unless `?results=1` inlines the envelope (Meta+content) on done targets, idx validated 0..targets_total-1 else 404, cancel of a terminal job → 409 "job already finished" else 200 {success,status:cancelled}. `api.go` scoped to the rule-2 changes: `batchMaxBody` (256 KiB) const, the four routes in `New`, and `ServeHTTP` applying the per-path cap once (`/v1/batch`→256 KiB, `/v1/extract`→pdfMaxUpload, else 64 KiB) and collapsing every batch path to a fixed metrics label via `batchObservePath` (`/v1/batch` or `/v1/batch/{id}`, never a job id). Each handler logs one `batch` line with caller/job_id/targets/status-or-reused and never a URL/hostname/idem_key. Given test byte-identical; all api tests pass under -race -count=3; make gate ok. |
 
 ## P5a review (owner, 2026-09-26)