Merge the P6 plan (asynchronous batch fetch), revised after owner review; Kyle to re-review

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-09-26 20:18:24 -07:00
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 # Sift P6 — asynchronous batch fetch
 Drafted 2026-09-26 by straylight (Hermes agent) from the design discussion with Kyle. Reviewer:
 Claude (when it frees up this evening). Implementer: Kyle's call.
 ## 1. Scope
 In: an asynchronous batch fetch endpoint. An agent submits a list of targets (URLs, each with the
 same per-target options as `/v1/fetch`) and gets a job ID back immediately; it polls for per-target
 results later. One job drains **serially** — one target at a time — in the background.
 Out:
 - Parallel fan-out. A batch is deliberately slow; it is the tool for research threads that are
  already expected to take a long time, not for interactive fetches.
 - Crawling, retry-with-backoff at the target level, and anything that requires a headless browser.
 - Firecrawl compatibility. This is a native-only feature; no Hermes plugin.
 The guard, auth and restricted-caller rules do not change: each target is fetched exactly like a
 page, through the same SSRF guard and the same per-caller/host gates.
 ## 2. Why agents need this (2026-09-26)
 `docs/PLAN.md` §13 (Kyle): "an agent that has collected a series of targets and wants them fetched
 without holding a request open per target." Today that means a loop of `sift fetch` calls — one
 request held open per URL, each its own tool call and gate. A batch lets the agent submit the whole
 list, walk away, and collect once. It builds on the P5 infrastructure that already exists: the
 `dcache` SQLite store, the `global`/`per` concurrency gates, and the `doFetch` pipeline.
 ## 3. Endpoints and wire shapes
 | Method | Path | Result |
 |---|---|---|
 | `POST /v1/batch` | submit a list of targets | `202` created/reused, `400` malformed, `422` refused up front or over a cap, `429` caller/jobs busy |
 | `GET /v1/batch/{id}` | status summary; `?results=1` inlines results | `200`, `401`/`404` |
 | `GET /v1/batch/{id}/{idx}` | one target's status and result | `200`, `401`/`404` |
 | `DELETE /v1/batch/{id}` | cancel | `200`, `409` already finished, `401`/`404` |
 With `[batch] disabled = true` every batch endpoint answers `503 batch disabled`.
 `POST /v1/batch` request — each target is the `/v1/fetch` field set minus the outer URL:
 ```json
 {"targets": [{"url": "…", "mode": "clean", "question": "…", "pages": "…", "grep": "…",
              "jq": "…", "context": true, "recover": false}, …]}
 ```
 Response `202`:
 ```json
 {"success": true, "job_id": "…", "status": "queued", "targets": 3, "reused": false}
 ```
 `GET /v1/batch/{id}` (a summary: no results, since 32 inline results can be ~6 MB in one agent
 tool call):
 ```json
 {"job_id": "…", "status": "partial", "targets_total": 3, "targets_done": 3,
 "created_at": "2026-09-27T01:02:03Z", "targets": [
   {"idx": 0, "url": "…", "status": "done"},
   {"idx": 1, "url": "…", "status": "failed", "error": "blocked: private address …", "hint": "browser"}
 ]}
 ```
 `?results=1` adds `"result"` (the `/v1/fetch` envelope) to every `done` target.
 `GET /v1/batch/{id}/{idx}` returns `{"job_id", "idx", "url", "status", "result"?, "error"?,
 "hint"?}`. A `pending` target has `status: "pending"` and no `result`/`error`. A `202` for a new
 job says `"status": "queued"`; a reused one says the job's current status. `DELETE` → `200 {"success": true, "status":
 "cancelled"}`.
 Job status vocabulary: `queued → running → done | partial | failed | cancelled`. Target status:
 `pending → running → done | failed`.
 ## 4. Storage (`dcache`)
 Two tables, added to `internal/dcache` (which owns the single SQLite connection):
 - `batch_job(id, caller, caller_class, idem_key, status, error, targets_total, targets_done,
  created_at, lease, nbytes)`
 - `batch_target(job_id, idx, url, options, status, result, error, hint)` — `result` is the JSON
  envelope, `NULL` until the target finishes.
 Batch storage is a coherent whole: it is bounded by its own lease GC and a byte budget, **not** by
 the content cache's LRU. `EvictBatchOldest` evicts whole jobs oldest-`lease`-first; a
 `queued`/`running` job is never byte-evicted. `MarkInFlightFailed(reason, now)` is the restart hook.
 ## 5. The runner (`internal/batch`)
 A new package with the job lifecycle and the serial state machine. Persistence is the `*dcache.DB`;
 the only injected behavior is a `FetchFunc func(ctx, Target) (Result, error)`.
 - **Idempotency (in v1).** A job has a random opaque `id` plus a derived `idem_key =
  SHA256(caller + "\x00" + canonical target list)`. Resubmitting the same (caller, targets) while
  the job's lease has not expired returns the existing job (`reused: true`) instead of a new one.
  Idempotency is lease-scoped, so it is "reuse within TTL, fresh after".
 - **Caps.** targets/job 32; live jobs/caller 1; live jobs total 8. "Live" is by status
  (`queued`/`running`), not lease. Exceeding a cap is a typed error the API maps to `422`/`429`.
 - **The caller.** `Submit` takes the `*auth.Caller`; the runner keeps it in memory with the job
  and passes it to every `FetchFunc` call (`func(ctx, *auth.Caller, Target)`), so the fetch runs
  under the caller's gates, pool slot, cache class and redaction. Only its name and class are
  stored.
 - **Workers.** `workers` (default 1, at most 2) share one round-robin over the live jobs, one
  target at a time. A job is `queued` until a worker first takes it, then `running`.
 - **Serial.** Targets drain in `idx` order; target `i+1` does not start until `i` is written.
 - **Busy.** A `FetchFunc` error wrapping `ErrRetryLater` (the API maps fetch `429`/`503` to it)
  leaves the target pending; it is tried again after 2 s, for up to 10 min, then failed.
 - **Failure isolation.** One target's error is stored per-target and the job continues; the job
  status is `done` (all ok), `failed` (all failed), or `partial` (mixed).
 - **Cancel.** `DELETE` flips the job `cancelled`, stops before the next target, and lets the
  in-flight target finish and store. Completed targets stay readable until the lease lapses.
 ## 6. Scheduling and fairness
 The workers run in the background, and every target still goes through the normal `acquire` gate
 (8 global, 2 per-host). With 1–2 workers the batch holds at most 1–2 of the 8 global slots, so
 interactive requests always have room. (The first draft let 8 live jobs each run a target at
 once, which could fill the whole gate.) On `429 busy` the worker **waits and retries** instead of
 failing: nobody is holding a socket open.
 Two shared resources get the same treatment:
 - **The PDF pool.** A batch extraction uses the pool caller name `<caller>/batch`, so it never
  takes the caller's own interactive slot. The single-flight key is unchanged, so a batch and an
  interactive request for the same PDF still share one child.
 - **The digest gate.** A batch question queues on it like any other digest. With one worker
  that is at most one batch digest at a time.
 Each batch fetch runs under the same 210 s deadline as a `/v1/fetch` request.
 ## 7. Retention and TTL
 A job carries a single sliding **lease**, bumped on submit, on every target completion, and on
 every read by its owner (the API calls `Touch` after the ownership check; the store's reads
 never write). All targets therefore share one expiry (the last completion's), and a
 slow consumer's reads keep a finished batch alive. GC deletes a job and its targets once the lease
 is older than the TTL (24 h). Completed results survive a restart and stay readable until the lease
 lapses; `queued`/`running` jobs are marked `failed` (`restart`) on startup and never resumed.
 ## 8. Restricted callers
 Compartmentalized-access systems: their usage is redacted as much as possible. The existing
 `logHost`/`logReason`/`logErr` machinery already blanks host, reason and error detail for
 `PermitRestricted` callers, and the digest/embed caches partition by caller class — the batch
 inherits all of it by passing the caller through. Two additions: batch log lines never carry a
 target URL or hostname for **any** caller, and `GET`/`DELETE` enforce job ownership, returning
 `404` (not `403`) for a job owned by another caller so a caller cannot probe for its existence.
 The `idem_key` is stored as a hash and never logged alongside its target list.
 ## 9. Caps and metrics (sized empirically)
 The caps are starting values, instrumented so they can be re-sized from observed data:
 - `sift_batch_jobs_total{outcome}` — `created|reused|done|partial|failed|cancelled|restart`
 - `sift_batch_targets_total{outcome}` — `ok|blocked|timeout|busy|upstream_4xx|upstream_5xx|
  unsupported|too_long|cancel`
 - `sift_batch_queue_depth`, `sift_batch_targets_inflight` (gauges)
 - `sift_batch_job_seconds`, `sift_batch_target_seconds`, `sift_batch_result_bytes` (histograms)
 Both `outcome` counters fold any value outside their known set to `other`, so a raw string never
 becomes a label. `result_bytes` is what sizes the byte budget (64 MiB).
 ## 10. CLI and skill
 - `sift batch submit <targets.json>` (`-` reads stdin; prints `job_id` and `reused`).
 - `sift batch status [--results] <job_id>` (the summary; `--results` inlines every result).
 - `sift batch get <job_id> <idx>` (one result).
 - `sift batch cancel <job_id>`.
 - `skill/SKILL.md`: use `sift batch submit` for a list of targets instead of a loop of
  `sift fetch`; `sift batch status` to collect.
 - `[batch]` config block: `disabled`, `targets_per_job`, `jobs_per_caller`, `jobs_total`,
  `workers`, `ttl`, `max_bytes`.
  The `/v1/batch` body cap (256 KiB, vs the 64 KiB global) is a constant, not config.
 ## 11. Refactor of existing code (explicit)
 `v1fetch` today inlines the whole per-target pipeline (guard → `doFetch` → `recover` →
 render/digest → context → envelope). The batch worker needs the same pipeline for one target. It is
 extracted into one shared method, `func (s *Server) fetchTarget(ctx, *auth.Caller, batch.Target)
 (batch.Result, error)`, that both `v1fetch` and the runner's adapter (`batchFetch`) call. It is its
 own task (04), done before any batch endpoint exists, so the diff is a pure move. `v1fetch` keeps its
 exact response shape and behavior — its existing tests must pass unchanged. This is the one change
 to working code in P6 and is called out for reviewer attention.
 ## 12. Acceptance (contract) tests
 Acceptance-first, as in P5a: given tests compiled against a panic-only skeleton, failing for the
 intended reasons. See `docs/plans/p6/_files/` and the task table in `docs/plans/p6/README.md`.
 1. `dcache`: round trip, idempotency lookup (lease expiry, caller scope, status filter), live
   counts, ordered targets, exactly-once `targets_done` and lease bumps, sweep, byte eviction
   (oldest first, never a live job), `MarkInFlightFailed`, `BatchNbytes`.
 2. `batch` runner:
   - serial order (peak in flight 1), with the caller passed to every fetch;
   - round-robin between jobs, and `queued` → `running`;
   - failure isolation (`partial`, `failed`);
   - idempotent resubmit, including after `done`, but a new job after a cancel;
   - all three caps and `ErrNoTargets`; cancel (the in-flight target stored, later ones `pending`);
   - busy retry and its limit; panic recovery (the panic value not echoed); the hooks.
 3. `metrics`: series names, labels, folding to `other`.
 4. `api` `fetchTarget`: the same content and envelope as `/v1/fetch`; its errors as `*fetch.Error`.
 5. `api` wiring: the runner through `fetchTarget`, a private-resolving name blocked per target,
   metrics through the hooks, outcome classes, busy → `ErrRetryLater`.
 6. `guard.PreCheck`: no resolution; the port, scheme, userinfo and literal rules; the allow list.
 7. `api` endpoints:
   - submit `202` and idempotent resubmit;
   - `400`/`422` refusals (the guard pre-check naming the index, 33 targets);
   - the 256 KiB body; the per-target `blocked` failure giving `partial`;
   - summary, one result, `?results=1`;
   - ownership `404` (GET, one result, DELETE); cancel and `409`;
   - no job id in `/metrics`.
 8. `config`: the `[batch]` block, `ParseSize`. `cmd/sift`: `parseBatchArgs`.
 ## 13. Rollout
 1. Implementer builds P6 on a branch; the reviewer (Claude) checks §11, the `v1fetch` refactor,
   and the caps/lease semantics.
 2. Orion pin bump with the `[batch]` config block; no `MemoryMax` change.
 3. Skill update ships with the pin bump.
 4. Watch `sift_batch_*` and tirith for a week; the success measure is that a research thread's
   one-request-per-URL fetch loop collapses into a single batch submit.
 ## 14. Changes after the plan was written
 **2026-09-26 evening, owner review (Claude), at Kyle's direction ("fold them into the plan").**
 The design stands; these were implementation-blocking or would have hurt agents:
 1. **The caller was lost.** `FetchFunc` had no caller and the runner was built once, so the given
   api test (`batch.New(db, s.fetchTarget, …)`) could not compile against the specified
   `fetchTarget(ctx, *auth.Caller, Target)`. Made to compile, it would have fetched every target
   with no caller: no per-caller gates, pool limit, cache class or redaction. Now `Submit` takes
   the `*auth.Caller` and `FetchFunc` receives it (§5).
 2. **Task 01 rule 1 contradicted its test.** Store reads no longer bump the lease; the API calls
   `Touch` after an owner's read (§7).
 3. **Batch could starve interactive fetches.** 8 live jobs × 1 target filled the 8-slot global
   gate. The busy-retry of §6 was in no task. Now there are 1–2 round-robin workers, busy-retry
   is in the runner, a batch PDF uses its own pool name, and a per-target deadline applies (§5, §6).
 4. **Flaky, networked API tests.** Two tests fetched `https://example.com/`, and the cancel test
   raced the fetch. Every api test is now local, using held `httptest` servers and a fake DNS
   name for the private-address case.
 5. **A resubmit could return a dead job.** A failed or cancelled job was reused for 24 h, and
   polling it kept extending that. Now only `queued`/`running`/`done`/`partial` jobs are reused.
 6. **Reads were too large.** `GET` inlined every result (up to ~6 MB). It is now a summary, with
   `GET …/{idx}` and `?results=1` (§3). The CLI gains `get` and `status --results`.
 7. **Body cap.** The global 64 KiB `MaxBytesReader` runs in `ServeHTTP`, so a handler cannot
   raise it. `ServeHTTP` now picks 256 KiB for `/v1/batch`. Request metrics use a fixed
   `/v1/batch/{id}` label, so a job id never becomes a label value.
 8. **Submit pre-check.** `guard.ParseURL` rejects the test's own loopback port and knows nothing
   of the allow list. New `Guard.PreCheck` is `CheckURL` without resolution (given verbatim in
   task 05). A private IP literal is now refused at submit; a *name* that resolves privately
   still fails per target at fetch time.
 9. **Task shape.** 5 tasks → 8, one package each where possible. The old task 03 (refactor +
   endpoints + main) is now 04 (refactor only), 05 (runner wiring), 06 (endpoints) and 07
   (serve/config). Every task restates the APIs it uses from earlier tasks. Every given test
   compiles against a panic-only skeleton and fails there on `panic: todo`.
 10. **Also fixed:**
    - the `ErrBusy` (jobs total) cap now has a test;
    - the `202` status is `queued`, consistent with the workers;
    - the `restart` outcome is counted by `serve`;
    - `Options.Context` is `*bool`, keeping `/v1/fetch`'s default.
 **Sequencing.** P6 starts after P5c merges. P5b/P5c change `v1fetch` (the digest meta gains
 `retrieval`/`embedded`), which is the code task 04 moves. Recheck the api given tests against
 a skeleton built on post-P5c master before the run.
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 # P6 task 01: batch tables, lease, GC, byte budget in `internal/dcache`
 **Branch:** `p6` (`git switch -c p6 master` if it does not exist, else `git switch p6`; `git status --short` must be empty, otherwise stop)
 **Commit subject:** `dcache: batch job and target tables with a sliding lease, sweep and byte budget`
 Add the batch job store to the existing `internal/dcache` SQLite database. No HTTP, no worker —
 this task is storage only. `dcache` owns the single SQLite connection, so the batch tables and
 their accessors live here; the runner (task 02) and API (task 05) call them.
 ## Context
 `dcache.DB` already opens one SQLite connection (`SetMaxOpenConns(1)`, WAL) in `Open`, owns
 `maxBytes`, `evict()`, `Size()`, and `Stats()`. The batch store is a sibling, not a member of the
 content-addressed cache: a batch job is an atomic unit (a row plus its target rows) and must be
 evicted whole by lease, never row-by-row by the content LRU.
 ## Schema (add to `Open`)
 ```sql
 CREATE TABLE IF NOT EXISTS batch_job (
    id            TEXT PRIMARY KEY,
    caller        TEXT NOT NULL,
    caller_class  TEXT NOT NULL,          -- 'fleet' | 'restricted'
    idem_key      TEXT NOT NULL,
    status        TEXT NOT NULL,          -- queued|running|done|partial|failed|cancelled
    error         TEXT NOT NULL DEFAULT '',
    targets_total INTEGER NOT NULL,
    targets_done  INTEGER NOT NULL DEFAULT 0,
    created_at    INTEGER NOT NULL,       -- unix seconds
    lease         INTEGER NOT NULL,       -- unix seconds; bumped on submit/completion/read
    nbytes        INTEGER NOT NULL DEFAULT 0  -- sum of stored per-target result bytes
 );
 CREATE TABLE IF NOT EXISTS batch_target (
    job_id  TEXT NOT NULL,
    idx     INTEGER NOT NULL,             -- order within the job, 0..n-1
    url     TEXT NOT NULL,
    options TEXT NOT NULL,                -- JSON: the per-target options
    status  TEXT NOT NULL,                -- pending|running|done|failed
    result  TEXT,                         -- JSON result envelope, or NULL
    error   TEXT,                         -- error message, or NULL
    hint    TEXT,                         -- error hint, or NULL
    PRIMARY KEY (job_id, idx)
 );
 CREATE INDEX IF NOT EXISTS batch_job_idem  ON batch_job(caller, idem_key);
 CREATE INDEX IF NOT EXISTS batch_job_lease ON batch_job(lease);
 ```
 `result`/`error`/`hint` are `NULL` until the target finishes. The `result` JSON is the
 `/v1/fetch`-shaped envelope, bounded by the output cap at write time (the render step enforces the cap;
 the store just stores what it is given and counts its bytes into `nbytes`).
 ## Public surface (exact names — the given test compiles against them)
 ```go
 type BatchJob struct {
    ID           string
    Caller       string
    CallerClass  string
    IDemKey      string
    Status       string
    Error        string
    TargetsTotal int
    TargetsDone  int
    CreatedAt    int64
    Lease        int64
    NBytes       int64
 }
 type BatchTarget struct {
    JobID   string
    Idx     int
    URL     string
    Options string
    Status  string
    Result  *string
    Error   *string
    Hint    *string
 }
 func (d *DB) CreateBatchJob(j BatchJob) error
 func (d *DB) BatchJob(id string) (BatchJob, bool)
 func (d *DB) BatchJobByIDem(caller, idemKey string, now int64, ttl time.Duration) (string, bool)
 func (d *DB) LiveBatchJobs(caller string) int
 func (d *DB) LiveBatchJobsTotal() int
 func (d *DB) PutBatchTargets(jobID string, targets []BatchTarget) error
 func (d *DB) BatchTargets(jobID string) ([]BatchTarget, bool)
 func (d *DB) UpdateBatchTarget(jobID string, idx int, now int64, status string, result, errMsg, hint *string) error
 func (d *DB) SetBatchJobStatus(id, status, errMsg string, now int64) error
 func (d *DB) TouchBatchJob(id string, now int64) error
 func (d *DB) SweepBatch(now int64, ttl time.Duration) int
 func (d *DB) EvictBatchOldest(maxBytes int64) int
 func (d *DB) MarkInFlightFailed(reason string, now int64) int
 func (d *DB) BatchNbytes() int64
 ```
 Every method that touches time takes an explicit `now` (unix seconds) — the store is pure and the
 caller decides the clock, so the given test asserts exact lease values.
 ## Rules
 1. **Sliding lease.** `CreateBatchJob` stores the job as given (the caller sets `Lease`/`CreatedAt`).
   `UpdateBatchTarget`, `SetBatchJobStatus`, `TouchBatchJob`, and `MarkInFlightFailed` set the job
   lease to their `now`. **Reads never write:** `BatchJob`, `BatchTargets` and the counts change
   nothing, so the given test can assert exact lease values after reading. A consumer's read keeps
   a job alive because the API calls `TouchBatchJob` after it (task 05), not because the read does.
 2. **No partial-job reads leak a competing caller.** Every accessor is keyed by `job_id` only; the
   caller filter is the API layer's job (task 05). The store stores what it is told and returns
   what is asked.
 3. **Idempotency lookup.** `BatchJobByIDem(caller, idemKey, now, ttl)` returns the id of a job with
   that `(caller, idem_key)` whose `lease + ttl > now` **and whose status is `queued`, `running`,
   `done` or `partial`**. A `failed` job (including one killed by a restart) or a `cancelled` one
   is never returned: resubmitting the same list after either starts a new job. If several match,
   return the newest by `created_at`.
 4. `BatchTargets` returns targets in `idx` order. `UpdateBatchTarget` increments `targets_done`
   exactly once per target that transitions *into* `done`/`failed` (a re-write of the same target
   does not double-count), bumps the job lease to `now`, and adds `len(result)` to `nbytes` when a
   result is written.
 5. `SweepBatch(now, ttl)` deletes every job whose `lease + ttl <= now`, and its target rows, and
   returns the number of jobs deleted. It is the only thing that removes a finished job by time; the runner calls it (task 02).
 6. `EvictBatchOldest(maxBytes)` evicts **whole jobs** (oldest `lease` first) until `BatchNbytes()`
   is `<= maxBytes`, and returns the number evicted. A job in `queued`/`running` is never
   byte-evicted (only lease-GC, cancel, or restart removes an active job). The runner (task 02) calls it
   after each target result is written; it is separate from the content-cache `evict()`.
 7. `MarkInFlightFailed(reason, now)` marks every `queued`/`running` job `failed` with
   `error=reason`, bumps their lease to `now`, and returns the count. This is the restart
   reconciliation hook; `serve` calls it on startup (task 06).
 8. `BatchNbytes()` sums `nbytes` over `batch_job`. Batch bytes are **not** included in `Size()` or
   the content `evict()` union; batch is a coherent unit with its own budget.
 9. Accessors follow the existing `dcache` style: return `(value, bool)` or `error`, never panic,
   count a miss in the appropriate `*M` counter. Reuse the existing `ClassFleet`/`ClassRestricted`
   constants for `caller_class`.
 ## Given
 Copy `_files/dcache/batch_test.go` → `internal/dcache/batch_test.go`. It opens an in-memory `DB`
 and asserts the create/read round trip, `BatchJobByIDem` lease expiry, caller scoping and the
 status filter (rule 3), live-job
 counts, ordered targets, the exactly-once `targets_done`/lease-bump rules, `SweepBatch`,
 `EvictBatchOldest` (oldest-first, never a live job), `MarkInFlightFailed`, and `BatchNbytes`.
 ## Steps
 - [ ] **1.** Branch; copy the given test. **2. See it fail** (`go test ./internal/dcache/` does not compile).
 - [ ] **3.** Schema in `Open`, the types, the methods, in a new `internal/dcache/batch.go`.
 - [ ] **4.** `gofmt -w`; `go test -race -count=3 ./internal/dcache/` → `ok` (every existing test too).
 - [ ] **5.** `make gate`. **6.** Row `p6/01-batchstore` in `docs/implementer-log.md`; commit.
 ```sh
 git add internal/dcache docs/implementer-log.md
 git commit -F .state/commit-msg.txt
 ```
 ## Done when
 - The given and existing dcache tests pass under `-race -count=3`; `make gate` ok; the given file is byte-identical.
@@ -0,0 +1,210 @@
 # P6 task 02: the batch runner in `internal/batch`
 **Branch:** `p6` (`git switch p6`; `git status --short` must be empty, otherwise stop)
 **Commit subject:** `batch: store-backed job runner — serial per job, round-robin workers, caps, idempotency, cancel, retry`
 ## Goal
 A new package `internal/batch`: the job lifecycle. It creates a job, lets a small pool of
 workers drain its targets one at a time, writes each outcome to the store, handles cancellation,
 retries a target whose fetch was only busy, and enforces the caps and idempotency.
 It knows **nothing** about HTTP, the guard, or the real fetch pipeline: the per-target work is an
 injected `FetchFunc`, and persistence is the `*dcache.DB` from task 01.
 ## Files
 - Copy: `_files/batch/runner_test.go` → `internal/batch/runner_test.go`
 - Create: `internal/batch/batch.go` (types, `New`, `Submit`, `Cancel`, `Status`, `Touch`, `Close`),
  `internal/batch/worker.go` (the workers and the drain)
 - Modify: `docs/implementer-log.md`
 ## What already exists (do not re-read these packages; this is their API)
 ```go
 // internal/dcache (task 01). Every time argument is unix seconds.
 type BatchJob struct{ ID, Caller, CallerClass, IDemKey, Status, Error string; TargetsTotal, TargetsDone int; CreatedAt, Lease, NBytes int64 }
 type BatchTarget struct{ JobID string; Idx int; URL, Options, Status string; Result, Error, Hint *string }
 func (d *DB) CreateBatchJob(j BatchJob) error
 func (d *DB) BatchJob(id string) (BatchJob, bool)                          // a pure read
 func (d *DB) BatchJobByIDem(caller, idemKey string, now int64, ttl time.Duration) (string, bool) // queued/running/done/partial only
 func (d *DB) LiveBatchJobs(caller string) int                             // queued + running
 func (d *DB) LiveBatchJobsTotal() int
 func (d *DB) PutBatchTargets(jobID string, targets []BatchTarget) error
 func (d *DB) BatchTargets(jobID string) ([]BatchTarget, bool)             // in idx order
 func (d *DB) UpdateBatchTarget(jobID string, idx int, now int64, status string, result, errMsg, hint *string) error
 func (d *DB) SetBatchJobStatus(id, status, errMsg string, now int64) error
 func (d *DB) TouchBatchJob(id string, now int64) error
 func (d *DB) SweepBatch(now int64, ttl time.Duration) int
 func (d *DB) EvictBatchOldest(maxBytes int64) int
 const ClassFleet, ClassRestricted = "fleet", "restricted"
 // internal/auth
 type Caller struct{ Name, Workspace, KeySHA256 string }
 ```
 ## Interfaces (exact: the given test compiles against them)
 ```go
 package batch
 type Options struct {
 	Mode     string `json:"mode,omitempty"`
 	Question string `json:"question,omitempty"`
 	Pages    string `json:"pages,omitempty"`
 	Grep     string `json:"grep,omitempty"`
 	JQ       string `json:"jq,omitempty"`
 	Context  *bool  `json:"context,omitempty"` // nil = /v1/fetch's default (on when there is a question)
 	Recover  bool   `json:"recover,omitempty"`
 }
 type Target struct {
 	URL     string  `json:"url"`
 	Options Options `json:"options"`
 }
 // Result is a finished target: the /v1/fetch envelope's content, and every other envelope field
 // in Meta. It is stored JSON-encoded in the target's result column.
 type Result struct {
 	Content string         `json:"content"`
 	Meta    map[string]any `json:"meta,omitempty"`
 }
 // TargetError is a failure with an agent-facing hint. Status is the HTTP status the same
 // failure gets from /v1/fetch; the runner ignores it (the metrics hook reads it). Any other
 // error is stored with its Error() text and no hint.
 type TargetError struct {
 	Status    int
 	Msg, Hint string
 }
 func (e *TargetError) Error() string { return e.Msg }
 // FetchFunc does one target for the caller that submitted the job.
 type FetchFunc func(ctx context.Context, c *auth.Caller, t Target) (Result, error)
 type Job struct {
 	ID           string
 	Caller       string
 	Status       string // queued | running | done | partial | failed | cancelled
 	Error        string
 	TargetsTotal int
 	TargetsDone  int
 	CreatedAt    int64 // unix seconds
 }
 type TargetStatus struct {
 	Idx    int
 	URL    string
 	Status string // pending | running | done | failed
 	Result *Result
 	Error  string
 	Hint   string
 }
 // Hooks observe the runner for metrics. Any nil field is skipped.
 type Hooks struct {
 	Job        func(outcome string)                              // created, reused, done, partial, failed, cancelled
 	Target     func(err error, d time.Duration, resultBytes int) // once per stored target; err nil on success
 	JobSeconds func(d time.Duration)                             // submit → terminal, once per job
 	Depth      func(live int)                                    // live jobs, after every change
 	Inflight   func(n int)                                       // targets being fetched, after every change
 }
 type Config struct {
 	TTL           time.Duration // 0 → 24h
 	TargetsPerJob int           // 0 → 32
 	JobsPerCaller int           // 0 → 1
 	JobsTotal     int           // 0 → 8
 	Workers       int           // 0 → 1; values above 2 are clamped to 2
 	MaxBytes      int64         // 0 → 64 MiB
 	RetryWait     time.Duration // 0 → 2s: the pause before a busy target is tried again
 	RetryFor      time.Duration // 0 → 10m: how long one target may keep coming back busy
 	Hooks         Hooks
 }
 var (
 	ErrNoTargets      = errors.New("no targets")
 	ErrTooManyTargets = errors.New("too many targets")
 	ErrCallerBusy     = errors.New("busy")
 	ErrBusy           = errors.New("jobs busy")
 	ErrRetryLater     = errors.New("retry later") // a FetchFunc wraps this when the target was only busy
 )
 func New(db *dcache.DB, fetch FetchFunc, cfg Config, log *slog.Logger) *Runner // starts the workers
 func (r *Runner) Submit(ctx context.Context, c *auth.Caller, callerClass string, targets []Target) (id string, reused bool, err error)
 func (r *Runner) Cancel(id string) bool
 func (r *Runner) Status(id string) (Job, []TargetStatus, bool) // a pure read
 func (r *Runner) Touch(id string)                              // bumps the lease to now
 func (r *Runner) Close()                                       // stops the workers; waits for an in-flight fetch to return
 ```
 ## Rules
 1. **Submit, in this order:**
   - `len(targets) == 0` → `ErrNoTargets`.
   - **Idempotency.** `idem_key` = hex SHA-256 of `c.Name + "\x00" + json.Marshal(targets)`.
     If `BatchJobByIDem(c.Name, key, now, TTL)` finds a job, return its id with `reused = true`:
     no new job, no caps, `Hooks.Job("reused")`.
   - **Caps:** more than `TargetsPerJob` → `ErrTooManyTargets`; `LiveBatchJobs(c.Name) >= JobsPerCaller`
     → `ErrCallerBusy`; `LiveBatchJobsTotal() >= JobsTotal` → `ErrBusy`.
   - Store the job **`queued`** (random 16-byte hex id, `CreatedAt` = `Lease` = now) and its targets
     (`pending`, `Options` = the JSON of `t.Options`), **before returning**. Keep `c` in memory
     for this job: jobs never resume after a restart, so the caller is never persisted.
   - `Hooks.Job("created")`; `SweepBatch(now, TTL)`; wake a worker.
 2. **Workers.** `Workers` goroutines share one rotation of live jobs in submit order. A worker
   takes the next job in the rotation that has a pending target **and no target in flight**. It
   sets the job to `running` on its first target, fetches that one target, stores it, and moves
   on to the next job in the rotation. So:
   - each job is serial: its target `i+1` never starts before `i` is stored;
   - with one worker and two live jobs, their targets alternate (`a1 b1 a2 b2 …`);
   - a job that a worker has not reached yet stays `queued`.
 3. **One target:**
   - Call the `FetchFunc` with the job's caller, under a context that `Close` cancels. Recover
     a panic into the error `internal error` (never echo the panic value).
   - If the error wraps `ErrRetryLater`, the target stays `pending`: the worker goes on with the
     rotation, and the target is tried again after `RetryWait`. A target that has been coming
     back busy for longer than `RetryFor` is stored `failed` with the error's text.
   - Otherwise store it: success → `done` with the JSON of the `Result`; error → `failed`, with
     `TargetError`'s `Msg`/`Hint` or `err.Error()` and no hint.
   - Then call `Hooks.Target(err, time, len(result JSON))`, then `EvictBatchOldest(MaxBytes)`.
 4. **Terminal status.** When a job's last target is stored: all `done` → `done`; all `failed` →
   `failed`; a mix → `partial`. `SetBatchJobStatus`, then `Hooks.Job(status)` and
   `Hooks.JobSeconds(now − created)`, exactly once per job.
 5. **Cancel(id)** returns false for an unknown id or a job already terminal. Otherwise it sets the job
   `cancelled` at once. The in-flight target, if any, finishes and is stored; no further target
   starts; later targets stay `pending`. Storing that last target must not overwrite `cancelled`.
   `Hooks.Job("cancelled")` once.
 6. **Status(id)** maps the store rows; `Result` is decoded from the result column. It writes
   nothing. **Touch(id)** is `TouchBatchJob(id, now)`; the API calls it after an owner's read.
 7. **Hooks.Depth** gets the live-job count and **Hooks.Inflight** the in-flight count whenever
   either changes.
 8. Library code never panics; a store error is logged (`Warn`, with the job id, never a URL) and
   the job goes on. Log lines carry the job id, counts and statuses, **never a URL or host**.
 ## Facts
 - The given test uses an in-memory `dcache` and `FetchFunc`s that hold on channels, fail, return
  `ErrRetryLater`, or panic. It calls `Close` before the store closes.
 - `TestRoundRobin` holds the first target until the second job is submitted, then expects
  `a1 b1 a2 b2 a3 b3` from one worker.
 ## Steps
 - [ ] **1.** `git switch p6`; copy the given test. **2. See it fail** (does not compile).
 - [ ] **3.** `batch.go`, **4.** `worker.go`.
 - [ ] **5.** `gofmt -w`; `go test -race -count=3 ./internal/batch/` → `ok`. **6.** `make gate`.
 - [ ] **7.** Row `p6/02-runner`; commit.
 ```sh
 git add internal/batch docs/implementer-log.md
 git commit -F .state/commit-msg.txt
 ```
 ## Done when
 - The given test passes under `-race -count=3`; `make gate` ok; the given file is byte-identical.
 ## Stop and report if
 - A given test's timing can only be met by sleeping longer than `RetryWait` inside a worker.
@@ -0,0 +1,83 @@
 # P6 task 03: `sift_batch_*` series in `internal/metrics`
 **Branch:** `p6` (`git switch p6`; `git status --short` must be empty, otherwise stop)
 **Commit subject:** `metrics: sift_batch_* series (jobs, targets, depth, in-flight, durations, bytes)`
 Add the batch series to `internal/metrics` so the caps (32 targets, 1 job/caller, 8 jobs total)
 and the byte budget can be re-sized from observed data. **This task touches only
 `internal/metrics`**: task 05 wires these methods to the runner's `batch.Hooks`.
 ## Series (names and label values exact — the given test asserts these)
 | Metric | Type | Labels / meaning |
 |---|---|---|
 | `sift_batch_jobs_total` | counter | `outcome` ∈ `created`, `reused`, `done`, `partial`, `failed`, `cancelled`, `restart` |
 | `sift_batch_targets_total` | counter | `outcome` ∈ `ok`, `blocked`, `timeout`, `busy`, `upstream_4xx`, `upstream_5xx`, `unsupported`, `too_long`, `cancel` |
 | `sift_batch_queue_depth` | gauge | live jobs (`queued`+`running`) |
 | `sift_batch_targets_inflight` | gauge | targets currently being fetched |
 | `sift_batch_job_seconds` | histogram | wall time from submit to terminal status |
 | `sift_batch_target_seconds` | histogram | wall time per target |
 | `sift_batch_result_bytes` | histogram | stored bytes per target result |
 Classifying an error into a target outcome is task 05's job (it has the `*fetch.Error`); this
 package only records the label it is given.
 ## Public surface (exact names — the given test compiles against them)
 ```go
 // fields added to metrics.Set (registered in New)
 BatchJobsTotal       *prometheus.CounterVec // label "outcome"
 BatchTargetsTotal    *prometheus.CounterVec // label "outcome"
 BatchQueueDepth      prometheus.Gauge
 BatchTargetsInflight prometheus.Gauge
 BatchJobSeconds      prometheus.Histogram
 BatchTargetSeconds   prometheus.Histogram
 BatchResultBytes     prometheus.Histogram
 // methods (nil-guarded, like ObservePDF)
 func (s *Set) ObserveBatchJob(outcome string)
 func (s *Set) ObserveBatchTarget(outcome string)
 func (s *Set) SetBatchQueueDepth(n int)
 func (s *Set) SetBatchTargetsInflight(n int)
 func (s *Set) ObserveBatchJobSeconds(d time.Duration)
 func (s *Set) ObserveBatchTargetSeconds(d time.Duration)
 func (s *Set) ObserveBatchResultBytes(n int)
 ```
 Both `outcome` counters fold any value outside their known set to `other` — the same "a raw string
 never becomes a label" guard as `ObservePDF`. Job outcomes: `created, reused, done, partial,
 failed, cancelled, restart`. Target outcomes: `ok, blocked, timeout, busy, upstream_4xx,
 upstream_5xx, unsupported, too_long, cancel`.
 ## Rules
 1. A new file `internal/metrics/batch.go` adds the series to `metrics.Set` (registered in `New`),
   with `Observe…`/`Set…` methods mirroring `ObservePDF`/`ObserveDigest`, nil-receiver safe.
 2. Both `outcome` counters fold any value outside their known set to `other`: a raw string
   never becomes a label.
 3. The series are exposed through the existing `/metrics` and `/metrics.json` paths: no new
   endpoint. `Snapshot`/`writeMetricsJSON` do not need to list them.
 4. Histogram buckets: seconds as the existing request histograms; bytes
   `1K, 4K, 16K, 64K, 256K, 1M`.
 ## Given
 Copy `_files/metrics/batch_test.go` → `internal/metrics/batch_test.go`. It drives the `Observe…`
 methods, serves the `/metrics` handler (as `pdf_test.go` does), and asserts the exact series names,
 label values, gauge values, histogram counts, and that a raw outcome string is folded to `other`.
 ## Steps
 - [ ] **1.** `git switch p6`; copy the given test. **2. See it fail.**
 - [ ] **3.** `internal/metrics/batch.go` and the registration in `New`.
 - [ ] **4.** `gofmt -w`; `go test -race -count=3 ./internal/metrics/` → `ok`. **5.** `make gate`.
 - [ ] **6.** Row `p6/03-metrics`; commit.
 ```sh
 git add internal/metrics docs/implementer-log.md
 git commit -F .state/commit-msg.txt
 ```
 ## Done when
 - The given and existing metrics tests pass under `-race -count=3`; `make gate` ok; the given file is byte-identical.
@@ -0,0 +1,86 @@
 # P6 task 04: extract `v1fetch`'s pipeline into `fetchTarget`
 **Branch:** `p6` (`git switch p6`; `git status --short` must be empty, otherwise stop)
 **Commit subject:** `api: v1fetch's per-target pipeline becomes fetchTarget (no behaviour change)`
 > This is the one task in P6 that edits working code. It is a **move, not a rewrite**: the
 > reviewer will diff the old `v1fetch` body against `fetchTarget` line by line.
 ## Goal
 `v1fetch` today inlines the whole per-target pipeline: fetch → recover → PDF render or clean →
 question limit → digest → context → log line → envelope. The batch worker (task 05) needs the
 same pipeline for one target. Move it into one method that both call:
 ```go
 // internal/api/target.go
 func (s *Server) fetchTarget(ctx context.Context, c *auth.Caller, t batch.Target) (batch.Result, error)
 ```
 `v1fetch` keeps its exact responses. **Every existing api test must pass unchanged.**
 ## Files
 - Copy: `_files/api/fetchtarget_test.go` → `internal/api/fetchtarget_test.go`
 - Create: `internal/api/target.go` (`fetchTarget`)
 - Modify: `internal/api/api.go` (`v1fetch` shrinks; `doFetch` takes a `context.Context` in place of
  the `*http.Request`, and its call sites pass `r.Context()`), `docs/implementer-log.md`
 ## What already exists
 ```go
 // internal/batch (task 02)
 type Options struct{ Mode, Question, Pages, Grep, JQ string; Context *bool; Recover bool }
 type Target struct{ URL string; Options Options }
 type Result struct{ Content string; Meta map[string]any }
 ```
 `fetch.Error{Status int; Msg, Hint string; RetryAfter int}` is the error type `writeFetchErr`
 already turns into a response.
 ## Rules
 1. **What stays in `v1fetch`:** `s.reqN.Add(1)`, the caller check, decoding `v1Req`, and the
   `400 invalid url` for a bad body or an empty URL. Then it builds a `batch.Target` from the
   request (`URL`, and `Mode`, `Question`, `Pages`, `Grep`, `JQ`, `Context`, `Recover` into
   `Options`), calls `s.fetchTarget(r.Context(), c, t)`, and:
   - on an error, `s.writeFetchErr(w, c, req.URL, err)`;
   - on success, `writeJSON(w, 200, env)` where `env` is `res.Meta` plus `"content": res.Content`.
 2. **What moves into `fetchTarget`, in the same order and unchanged:** the question truncation
   to 500 runes, the mode default and check, `wantCtx`, `doFetch`, the recover path
   (`recover.Try(ctx, …)`), the PDF branch (render, `pages`/`grep` errors, the question-chunk
   limit), the clean/raw branch, the digest, the context search, the `fetch` log line, and the
   envelope.
 3. **Errors that `v1fetch` wrote directly with `writeErr` become `*fetch.Error` values with the same
   status, message and hint:** `400 invalid url` for a bad mode, `400 raw mode does not apply to
   PDFs`. `writeFetchErr` then writes them exactly as before. The only visible difference is its
   `fetch failed` log line, which is fine.
 4. **The envelope:** `fetchTarget` returns `Result{Content: content, Meta: m}` where `m` holds every
   other key of today's `out` map (`mode`, `untrusted`, `source`, `warnings`, `sizes`, `timings`,
   and `pdf`, `digest`, `context` when present). Never put `content` in `Meta`.
 5. **`doFetch(ctx, c, rawURL, jq, onlyMain)`:** `r.Context()` becomes `ctx`. That is the only change
   in `doFetch`. `scrape` (the other caller) passes `r.Context()`.
 6. No new behaviour, no new log fields, no renamed JSON keys. If something cannot move without
   changing behaviour, stop and report it.
 ## Steps
 - [ ] **1.** `git switch p6`; copy the given test. **2. See it fail** (`fetchTarget` undefined).
 - [ ] **3.** `doFetch(ctx, …)` and its call sites. **4.** `target.go`. **5.** Shrink `v1fetch`.
 - [ ] **6.** `gofmt -w`; `go test -race -count=3 ./internal/api/` → `ok`, every existing test
  included. **7.** `make gate`.
 - [ ] **8.** Row `p6/04-fetchtarget`; commit.
 ```sh
 git add internal/api docs/implementer-log.md
 git commit -F .state/commit-msg.txt
 ```
 ## Done when
 - The two given tests and **every existing api test** pass under `-race -count=3`, with no
  existing test file modified; `make gate` ok; the given file is byte-identical.
 ## Stop and report if
 - An existing api test fails and fixing it would need a change to that test.
@@ -0,0 +1,149 @@
 # P6 task 05: the runner wired to `fetchTarget` and the metrics
 **Branch:** `p6` (`git switch p6`; `git status --short` must be empty, otherwise stop)
 **Commit subject:** `api: NewBatchRunner — the batch fetch adapter, retry on busy, outcome metrics; guard.PreCheck`
 ## Goal
 Build the production runner: its `FetchFunc` is an adapter over `fetchTarget` (task 04), and its
 hooks feed the `sift_batch_*` metrics (task 03). **No HTTP endpoints yet** (task 06). Also add
 `guard.PreCheck`, which task 06 uses to refuse a target at submit time.
 ## Files
 - Copy: `_files/api/batchrun_test.go` → `internal/api/batchrun_test.go`, and
  `_files/guard/precheck_test.go` → `internal/guard/precheck_test.go`
 - Create: `internal/api/batch.go` (`NewBatchRunner`, `batchFetch`, `batchOutcome`)
 - Modify:
  - `internal/api/api.go`: only the `Batch` field.
  - `internal/api/pdf.go`: only the pool caller name (rule 3).
  - `internal/guard/guard.go`: add **exactly** this method, verbatim. It is the only change allowed
    in the guard package.
  - `docs/implementer-log.md`
 ```go
 // PreCheck is CheckURL without name resolution: scheme, userinfo, host and port, and an IP
 // literal checked against the address rules. A hostname is not resolved here; the fetch-time
 // CheckURL and the dial-time Control still apply to it.
 func (g *Guard) PreCheck(raw string) error {
 	_, literal, err := ParseURL(raw)
 	if err != nil && !(literal.IsValid() && g.allows(literal)) {
 		return err
 	}
 	if literal.IsValid() {
 		return g.CheckAddr(literal)
 	}
 	return nil
 }
 ```
 ## What already exists
 ```go
 // internal/batch (task 02)
 type Options struct{ Mode, Question, Pages, Grep, JQ string; Context *bool; Recover bool }
 type Target struct{ URL string; Options Options }
 type Result struct{ Content string; Meta map[string]any }
 type TargetError struct{ Status int; Msg, Hint string }
 type FetchFunc func(ctx context.Context, c *auth.Caller, t Target) (Result, error)
 type Job struct{ ID, Caller, Status, Error string; TargetsTotal, TargetsDone int; CreatedAt int64 }
 type TargetStatus struct{ Idx int; URL, Status string; Result *Result; Error, Hint string }
 type Hooks struct {
 	Job        func(outcome string)
 	Target     func(err error, d time.Duration, resultBytes int)
 	JobSeconds func(d time.Duration)
 	Depth      func(live int)
 	Inflight   func(n int)
 }
 type Config struct{ TTL time.Duration; TargetsPerJob, JobsPerCaller, JobsTotal, Workers int; MaxBytes int64; RetryWait, RetryFor time.Duration; Hooks Hooks }
 var ErrNoTargets, ErrTooManyTargets, ErrCallerBusy, ErrBusy, ErrRetryLater error
 func New(db *dcache.DB, fetch FetchFunc, cfg Config, log *slog.Logger) *Runner
 func (r *Runner) Submit(ctx context.Context, c *auth.Caller, callerClass string, targets []Target) (string, bool, error)
 func (r *Runner) Cancel(id string) bool
 func (r *Runner) Status(id string) (Job, []TargetStatus, bool)
 func (r *Runner) Touch(id string)
 func (r *Runner) Close()
 // internal/metrics (task 03), on s.Prom
 ObserveBatchJob(outcome string); ObserveBatchTarget(outcome string)
 SetBatchQueueDepth(n int); SetBatchTargetsInflight(n int)
 ObserveBatchJobSeconds(d time.Duration); ObserveBatchTargetSeconds(d time.Duration); ObserveBatchResultBytes(n int)
 // internal/api (task 04 and before)
 func (s *Server) fetchTarget(ctx context.Context, c *auth.Caller, t batch.Target) (batch.Result, error)
 func (s *Server) caller(w http.ResponseWriter, r *http.Request) *auth.Caller // nil after writing 401/403
 func (s *Server) callerClass(c *auth.Caller) string
 func (s *Server) logErr(c *auth.Caller, err error) any
 // requestDeadline (210 s), maxReqBody (64 KiB), writeErr, writeJSON
 ```
 ## Interfaces added here
 ```go
 // in Server (after pdfPoolOnce):
 	Batch *batch.Runner // nil: the /v1/batch endpoints (task 06) answer 503 "batch disabled"
 // NewBatchRunner builds the runner that serve (task 07) and the tests use: its FetchFunc is
 // batchFetch and its Hooks feed s.Prom. cfg.Hooks is overwritten.
 func (s *Server) NewBatchRunner(db *dcache.DB, cfg batch.Config) *batch.Runner
 func (s *Server) batchFetch(ctx context.Context, c *auth.Caller, t batch.Target) (batch.Result, error)
 func batchOutcome(err error) string
 ```
 ## Rules
 1. **`batchFetch`**, the runner's `FetchFunc`:
   - `context.WithTimeout(ctx, requestDeadline)`, mark the context as a batch fetch (an unexported
     context key), and call `s.fetchTarget`.
   - Map its error:
     - a `*fetch.Error` with status `429` or `503` → `fmt.Errorf("%s: %w", fe.Msg, batch.ErrRetryLater)`,
       so the runner retries it;
     - any other `*fetch.Error` → `&batch.TargetError{Status, Msg, Hint}`, with `502` rewritten to
       `500 internal error` as `writeFetchErr` does, and `s.blockN.Add(1)` for a `403`;
     - anything else → `&batch.TargetError{Status: 500, Msg: "internal error"}`, logged `Error`
       with `s.logErr(c, err)`.
 2. **Hooks** (in `NewBatchRunner`):
   - `Job` → `ObserveBatchJob`;
   - `Target(err, d, n)` → `ObserveBatchTarget(batchOutcome(err))`, `ObserveBatchTargetSeconds(d)`, and
     `ObserveBatchResultBytes(n)` when `err == nil`;
   - `JobSeconds`, `Depth`, `Inflight` → the matching `s.Prom` methods.
   - `batchOutcome(err)` is:
     - `ok` for nil;
     - `busy` for an error wrapping `ErrRetryLater` (the runner gave up retrying);
     - otherwise, by `TargetError.Status`: `403` `blocked`, `429` `busy`, `504` `timeout`,
       `415` `unsupported`, `422` whose message starts `document too long` `too_long`, other
       4xx `upstream_4xx`, 5xx `upstream_5xx`; any other error `upstream_5xx`.
 3. **The PDF pool under a batch:** in `extractPDF`, the pool's caller argument is `c.Name+"/batch"`
   when the context carries the batch mark, else `c.Name` as today. A batch extraction then
   never takes the caller's own interactive slot. The single-flight key is unchanged, so a batch
   and an interactive extraction of the same PDF still share one child.
 4. Log lines added here carry the caller and the job id, **never a target URL or hostname**. The
   per-target `fetch` line inside `fetchTarget` is unchanged.
 ## Facts
 - The given api test builds the server through `s.NewBatchRunner` over an in-memory `dcache`
  (`newBatchServer`). Targets are local `httptest` servers, or `internal.test`, which the test's
  `LookupIP` resolves to `10.0.0.5`.
 - `TestBatchFetchErrors` fills the 8-slot global gate with `s.acquire` so the next fetch is
  refused busy after `acquire`'s 5 s wait.
 - `batchrun_test.go` also holds the helpers task 06's test uses; it is a given file like the others.
 ## Steps
 - [ ] **1.** `git switch p6`; copy the two given tests. **2. See them fail.**
 - [ ] **3.** `PreCheck` (verbatim). **4.** `batch.go`. **5.** The `Batch` field and the pool name.
 - [ ] **6.** `gofmt -w`; `go test -race -count=3 ./internal/api/ ./internal/guard/` → `ok`.
  **7.** `make gate`.
 - [ ] **8.** Row `p6/05-batch-wiring`; commit.
 ```sh
 git add internal/api internal/guard/guard.go internal/guard/precheck_test.go docs/implementer-log.md
 git commit -F .state/commit-msg.txt
 ```
 ## Done when
 - The given tests and every existing api and guard test pass under `-race -count=3`; `make gate`
  ok; the given files are byte-identical.
@@ -0,0 +1,112 @@
 # P6 task 06: the `/v1/batch` endpoints
 **Branch:** `p6` (`git switch p6`; `git status --short` must be empty, otherwise stop)
 **Commit subject:** `api: /v1/batch — submit, status summary, one result, cancel`
 ## Goal
 The HTTP surface over `s.Batch` (task 05): submit, a status summary, one target's result, and
 cancel, with the submit-time guard pre-check, the caps as HTTP statuses, and ownership.
 ## Files
 - Copy: `_files/api/batch_test.go` → `internal/api/batch_test.go`
 - Modify: `internal/api/batch.go` (the four handlers), `internal/api/api.go` (only the routes in
  `New` and `ServeHTTP`, rule 2), `docs/implementer-log.md`
 ## What already exists
 ```go
 // internal/batch (task 02)
 type Target struct{ URL string; Options Options }
 type Options struct{ Mode, Question, Pages, Grep, JQ string; Context *bool; Recover bool }
 type Result struct{ Content string; Meta map[string]any }
 type Job struct{ ID, Caller, Status, Error string; TargetsTotal, TargetsDone int; CreatedAt int64 }
 type TargetStatus struct{ Idx int; URL, Status string; Result *Result; Error, Hint string }
 var ErrNoTargets, ErrTooManyTargets, ErrCallerBusy, ErrBusy error
 func (r *Runner) Submit(ctx context.Context, c *auth.Caller, callerClass string, targets []Target) (string, bool, error)
 func (r *Runner) Cancel(id string) bool
 func (r *Runner) Status(id string) (Job, []TargetStatus, bool) // a pure read
 func (r *Runner) Touch(id string)                              // bumps the lease to now
 // internal/guard (task 05)
 func (g *Guard) PreCheck(raw string) error // "blocked: …" errors
 // internal/api
 	Batch *batch.Runner // in Server (task 05); nil → 503 "batch disabled"
 func (s *Server) caller(w http.ResponseWriter, r *http.Request) *auth.Caller // nil after writing 401/403
 func (s *Server) callerClass(c *auth.Caller) string
 // maxReqBody (64 KiB), writeErr(w, status, msg, hint), writeJSON(w, status, v), s.Prom.Observe(path, d, code)
 ```
 Add `const batchMaxBody = 256 << 10`.
 ## Rules
 1. **Routes** (in `New`): `POST /v1/batch`, `GET /v1/batch/{id}`, `GET /v1/batch/{id}/{idx}`,
   `DELETE /v1/batch/{id}`. Each starts with `s.caller(w, r)`.
 2. **`ServeHTTP`:**
   - The body cap is `batchMaxBody` for `/v1/batch` and `maxReqBody` for every other path. The cap
     is applied once, here: a handler cannot raise a cap already set.
   - Batch paths are observed with a fixed label: `/v1/batch` or `/v1/batch/{id}`. A job id must
     never become a label value.
 3. **Submit** (`POST /v1/batch`), checked in this order:
   - The body is `{"targets": [{"url", "mode", "question", "pages", "grep", "jq", "context",
     "recover"}, …]}`, each target flat with `/v1/fetch`'s field names. Bad JSON, a missing or
     empty list, an empty `url`, or a `mode` other than empty, `clean`, `raw` or `digest` →
     `400 invalid batch: …`.
   - `s.Guard.PreCheck(url)` for every target. The first failure → `422` with the message
     `blocked: target <idx>: <reason>`, and no job is created.
   - `s.Batch.Submit(r.Context(), c, s.callerClass(c), targets)`:
     - `ErrTooManyTargets` → `422 too many targets (max 32)` (the configured cap);
     - `ErrCallerBusy` → `429 busy: a batch of yours is still running`, `Retry-After: 30`;
     - `ErrBusy` → `429 batch jobs busy`, `Retry-After: 60`;
     - `ErrNoTargets` → `400`.
   - `202 {"success": true, "job_id", "status", "targets": n, "reused"}`. `status` is `"queued"`
     for a new job, and the job's current status for a reused one.
 4. **Ownership:** a job whose `Caller` is not `c.Name`, or an unknown id, is `404 not found` for
   every GET and DELETE. It is never `403`: a caller cannot probe for another caller's jobs.
 5. **Status** (`GET /v1/batch/{id}`): after the ownership check, `s.Batch.Touch(id)`, then
   `200 {"job_id", "status", "error" (only when set), "targets_total", "targets_done",
   "created_at" (RFC 3339, UTC), "targets": [{"idx", "url", "status", "error"?, "hint"?}]}`.
   - This is a summary: **no results**, because 32 inline results can be 6 MB, too much for one
     agent tool call.
   - With `?results=1`, each `done` target also carries `"result"`: the envelope, i.e. `Meta`
     plus `"content"`.
 6. **One result** (`GET /v1/batch/{id}/{idx}`): after ownership and `Touch`, `200 {"job_id", "idx",
   "url", "status", "result"?, "error"?, "hint"?}`. An `idx` that is not a number in
   `0..targets_total-1` → `404`. **Cancel** (`DELETE`): after ownership, a terminal job →
   `409 job already finished`; otherwise `Cancel` → `200 {"success": true, "status": "cancelled"}`.
 7. **Logging:** each batch handler logs one line: `batch` with `caller`, `job_id`, `targets` and
   `status` (or `reused`). **Never a target URL or hostname, for any caller**, and never the
   `idem_key`. The per-target `fetch` line inside `fetchTarget` is unchanged: it is redacted
   for restricted callers exactly as for `/v1/fetch`.
 ## Facts
 - `newBatchServer`, `pageServer` and `fakeDNS` come from `batchrun_test.go` (task 05). Targets
  are local `httptest` servers, some held on a channel, or `internal.test` (resolves to `10.0.0.5`).
 - `TestBatchBodyCap` posts 32 targets with questions, about 66 KiB: over `maxReqBody`, under
  `batchMaxBody`.
 ## Steps
 - [ ] **1.** `git switch p6`; copy the given test. **2. See it fail.**
 - [ ] **3.** The handlers. **4.** Routes and `ServeHTTP`.
 - [ ] **5.** `gofmt -w`; `go test -race -count=3 ./internal/api/` → `ok`. **6.** `make gate`.
 - [ ] **7.** Row `p6/06-api-endpoints`; commit.
 ```sh
 git add internal/api docs/implementer-log.md
 git commit -F .state/commit-msg.txt
 ```
 ## Done when
 - The given test and every existing api test pass under `-race -count=3`; `make gate` ok; the
  given file is byte-identical.
 ## Stop and report if
 - Any given test needs a URL that is not local, or a change to an existing test.
@@ -0,0 +1,101 @@
 # P6 task 07: the `[batch]` config and `serve` wiring
 **Branch:** `p6` (`git switch p6`; `git status --short` must be empty, otherwise stop)
 **Commit subject:** `serve: [batch] config; open the store, reap jobs killed by a restart, start the runner`
 ## Goal
 `sift serve` runs the batch runner from `[batch]` config. On startup it marks jobs that a restart
 killed as failed (they are never resumed). On shutdown it stops the runner before closing the store.
 ## Files
 - Copy: `_files/config/batch_test.go` → `internal/config/batch_test.go`
 - Modify: `internal/config/config.go` (the `Batch` type and field, `ParseSize`),
  `cmd/sift/serve.go` (rule 3), `dist/sift.toml.example` (rule 4), `docs/implementer-log.md`
 ## What already exists
 ```go
 // internal/batch (task 02)
 type Config struct{ TTL time.Duration; TargetsPerJob, JobsPerCaller, JobsTotal, Workers int; MaxBytes int64; RetryWait, RetryFor time.Duration; Hooks Hooks }
 func (r *Runner) Close()
 // internal/api (task 05)
 func (s *Server) NewBatchRunner(db *dcache.DB, cfg batch.Config) *batch.Runner
 	Batch *batch.Runner // in Server
 // s.Prom.ObserveBatchJob(outcome string) (task 03)
 // internal/dcache (task 01)
 func (d *DB) MarkInFlightFailed(reason string, now int64) int
 // internal/config
 func ParseDuration(s string, def time.Duration) time.Duration
 ```
 ## Interfaces added here
 ```go
 package config
 type Batch struct {
 	Disabled      bool   `toml:"disabled"`
 	TargetsPerJob int    `toml:"targets_per_job"`
 	JobsPerCaller int    `toml:"jobs_per_caller"`
 	JobsTotal     int    `toml:"jobs_total"`
 	Workers       int    `toml:"workers"`
 	TTL           string `toml:"ttl"`
 	MaxBytes      string `toml:"max_bytes"`
 }
 // in File, after Search:
 	Batch Batch `toml:"batch"`
 // ParseSize parses a positive byte count: a plain integer, or one with KiB, MiB or GiB.
 // Anything else, zero or negative returns def.
 func ParseSize(s string, def int64) int64
 ```
 ## Rules
 1. Batch is **on by default**: no `[batch]` block means the runner with its own defaults.
   `disabled = true` turns it off, and the endpoints then answer 503.
 2. `ParseSize` trims spaces and accepts only the binary suffixes `KiB`, `MiB`, `GiB`, or none (bytes).
 3. **`serve.go`:**
   - Open the `dcache` store when batch is on, as well as in today's cases: same path, same call.
     If the store cannot be opened, log `Warn` and run without batch.
   - Then, **before** building the runner: `n := cache.MarkInFlightFailed("restart", now)`, and call
     `srv.Prom.ObserveBatchJob("restart")` `n` times. Log `batch reaped` with `n` if `n > 0`.
   - `srv.Batch = srv.NewBatchRunner(cache, batch.Config{...})`, with the config fields: `TTL` via
     `ParseDuration(…, 0)` and `MaxBytes` via `ParseSize(…, 0)`. The runner's defaults fill the zeros.
   - On shutdown (both branches of the final `select`), `srv.Batch.Close()` before the process
     exits, when it is non-nil.
 4. **`dist/sift.toml.example`:** a commented `[batch]` block with the defaults, in the style of the
   file:
   ```toml
   # [batch]
   # disabled = false
   # targets_per_job = 32
   # jobs_per_caller = 1
   # jobs_total = 8
   # workers = 1          # at most 2: each worker fetches one target at a time
   # ttl = "24h"          # a job's results live this long after its last read or write
   # max_bytes = "64MiB"  # stored results; the oldest finished jobs go first
   ```
 ## Steps
 - [ ] **1.** `git switch p6`; copy the given test. **2. See it fail.**
 - [ ] **3.** `config.go`. **4.** `serve.go`. **5.** The example config.
 - [ ] **6.** `gofmt -w`; `go test -race -count=3 ./internal/config/ ./cmd/sift/` → `ok`. **7.** `make gate`.
 - [ ] **8.** Row `p6/07-serve-config`; commit.
 ```sh
 git add internal/config cmd/sift/serve.go dist/sift.toml.example docs/implementer-log.md
 git commit -F .state/commit-msg.txt
 ```
 ## Done when
 - The given test and every existing config and cmd test pass under `-race -count=3`; `make gate`
  ok; the given file is byte-identical.
@@ -0,0 +1,89 @@
 # P6 task 08: `sift batch`, README and skill
 **Branch:** `p6` (`git switch p6`; `git status --short` must be empty, otherwise stop)
 **Commit subject:** `cli: sift batch submit|status|get|cancel; README and skill`
 ## Goal
 Agents reach the batch endpoint through the CLI, as they do `fetch` and `search`. There is no
 Hermes plugin.
 ## Files
 - Copy: `_files/cmd_sift/batch_test.go` → `cmd/sift/batch_test.go`
 - Create: `cmd/sift/batchcmd.go` (`batchMain`, `parseBatchArgs`, one small function per verb)
 - Modify: `cmd/sift/main.go` (one `case "batch":` line and the usage text), `README.md`,
  `skill/SKILL.md`, `docs/implementer-log.md`
 ## What already exists
 - `cmd/sift`: `loadClient() (base, key string, err error)` reads `client.toml`; `searchcmd.go` is the
  pattern for a verb (build the request with the bearer header, decode the JSON envelope, exit
  non-zero on a non-2xx). Never put a key on the command line.
 - The endpoints (task 06):
  - `POST /v1/batch` `{"targets":[…]}` → `202 {"success","job_id","status","targets","reused"}`;
  - `GET /v1/batch/{id}` (summary; `?results=1` inlines results);
  - `GET /v1/batch/{id}/{idx}` (one result);
  - `DELETE /v1/batch/{id}`.
 ## Interfaces added here
 ```go
 // parseBatchArgs validates a `sift batch` command line (without "batch").
 func parseBatchArgs(args []string) (verb string, rest []string, err error)
 ```
 ```
 sift batch submit <targets.json|->     # prints {"job_id", "status", "reused"}
 sift batch status [--results] <job_id> # prints the status body (a summary unless --results)
 sift batch get <job_id> <idx>          # prints one target's result, as `sift fetch --json` would
 sift batch cancel <job_id>             # prints {"success", "status"}
 ```
 ## Rules
 1. `parseBatchArgs` accepts exactly the forms above:
   - `submit` with one argument (`-` means stdin);
   - `status` with a job id, optionally preceded by `--results`;
   - `get` with a job id and an `idx` that is a non-negative integer;
   - `cancel` with a job id.
   Anything else (no verb, a missing or extra argument, an unknown verb, a bad `idx`) is an
   error. `rest` is the arguments after the verb, unchanged.
 2. `submit` reads the file and checks it locally before calling the server: it must be a JSON
   object with a non-empty `targets` array. It may also be a bare array of targets or of URL
   strings; wrap either into `{"targets": […]}`, turning each string into `{"url": s}`.
 3. Every verb prints the server's JSON on stdout, and on a non-2xx prints the error envelope to
   stderr and exits with `exitFor(status, msg)`, as `fetch` does.
 4. **`README.md`**, a short "Batch" section:
   - the four endpoints;
   - the model: serial per job, one worker by default, round-robin across jobs;
   - the caps (32 targets, 1 live job per caller, 8 in all) and the 256 KiB body;
   - idempotency: the same list from the same caller returns the same job while it is live or
     has results;
   - the lease/TTL and restart semantics;
   - the summary-vs-results reads;
   - restricted-caller redaction;
   - the `sift_batch_*` metrics.
 5. **`skill/SKILL.md`**, a short section:
   - for several URLs you will read later, `sift batch submit` them once, rather than a loop of
     `sift fetch`;
   - poll with `sift batch status`, and read each result with `sift batch get <job> <idx>`;
   - don't use `--results` unless you need every result at once (it can be large);
   - a batch is slow on purpose: for one URL you need now, use `sift fetch`.
 ## Steps
 - [ ] **1.** `git switch p6`; copy the given test. **2. See it fail.**
 - [ ] **3.** `batchcmd.go`. **4.** `main.go`. **5.** README and skill.
 - [ ] **6.** `gofmt -w`; `go test -race -count=3 ./cmd/sift/` → `ok`. **7.** `make gate`.
 - [ ] **8.** Row `p6/08-cli-docs`; commit.
 ```sh
 git add cmd/sift README.md skill/SKILL.md docs/implementer-log.md
 git commit -F .state/commit-msg.txt
 ```
 ## Done when
 - The given test and every existing cmd test pass under `-race -count=3`; `make gate` ok; the
  given file is byte-identical.
@@ -0,0 +1,58 @@
 # P6 implementation plan: asynchronous batch fetch
 > **For the implementing model:** do not work from this file. The owner gives you one task file
 > at a time. This file is the index for the owner and the reviewer.
 **Goal:** an agent that has collected a series of targets (URLs) and wants them fetched without
 holding a request open per target submits them as one batch, gets a job ID back immediately, and
 polls for per-target results later. A batch is **deliberate and slow** — serial, one target at a
 time — so it is the tool for research threads, not for interactive fetches.
 Decisions (settled with the owner, 2026-09-26; revised after review the same evening, see
 `docs/P6.md` §14):
 - **Serial per job, few workers.** One worker by default (at most 2) drains all live jobs,
  round-robin, one target at a time. The batch therefore holds at most 1–2 of the 8 global fetch
  slots, so interactive requests are never starved. A target refused busy (fetch gate or PDF
  pool) is retried after a pause, for up to 10 minutes, then failed.
 - **The caller travels with the job.** The runner keeps each job's `*auth.Caller` in memory and
  hands it to every fetch, so per-caller gates, the PDF pool, the digest cache class and
  restricted-caller redaction all apply. Nothing about the caller is persisted beyond its name
  and class: jobs never resume after a restart.
 - **Caps.** targets/job 32; live jobs/caller 1; live jobs total 8; body 256 KiB. All instrumented
  (`sift_batch_*`).
 - **Idempotency in v1.** The same (caller, target list) returns the existing job while it is live or
  has results (`queued`/`running`/`done`/`partial`) and its lease holds. A failed or cancelled job
  is not reused.
 - **Storage.** `batch_job` + `batch_target` tables in the existing `dcache` SQLite, with its own
  byte budget (64 MiB), outside the content cache's LRU.
 - **Retention / TTL.** One sliding lease per job, bumped on submit, on every target write, and on
  every owner read (the API calls `Touch`; store reads never write). GC deletes a job when its
  lease is older than the TTL (24 h).
 - **Reads.** `GET /v1/batch/{id}` is a summary (statuses, errors). A result is read one at a time
  (`GET /v1/batch/{id}/{idx}`), or all at once with `?results=1`. 32 inline results can be 6 MB.
 - **Restart.** `queued`/`running` jobs are marked `failed` (`restart`) on startup; never resumed.
 - **Restricted callers.** Their fetches go through the same `fetchTarget` with the real caller,
  so the existing redaction applies. No caller can see another's job (404, never 403). Batch
  log lines never carry a target URL or hostname.
 | Task | Package | Given |
 |---|---|---|
 | 01-batchstore | `internal/dcache` | `dcache/batch_test.go` |
 | 02-runner | `internal/batch` | `batch/runner_test.go` |
 | 03-metrics | `internal/metrics` | `metrics/batch_test.go` |
 | 04-fetchtarget | `internal/api` (the one refactor of working code) | `api/fetchtarget_test.go` |
 | 05-batch-wiring | `internal/api` (+ `guard.PreCheck`, given verbatim) | `api/batchrun_test.go`, `guard/precheck_test.go` |
 | 06-api-endpoints | `internal/api` | `api/batch_test.go` |
 | 07-serve-config | `internal/config`, `cmd/sift/serve.go` | `config/batch_test.go` |
 | 08-cli-docs | `cmd/sift`, README, skill | `cmd_sift/batch_test.go` |
 Given files live under `_files/<package>/` (`cmd_sift` is `cmd/sift`); each task says where to
 copy its file. Every given test was compiled against a panic-only skeleton of the whole plan and
 fails there on `panic: todo`, not on a compile error.
 **How this plan was made:** design worked through with the owner from `docs/PLAN.md` §13 (future
 work) on top of the P5 pool (`internal/pdfpool`), cache (`internal/dcache`), and gate
 (`global`/`per` in `internal/api`) infrastructure. Acceptance tests first: the given tests are
 authored against this spec and compiled against a panic-only skeleton so they fail for the
 intended reasons before each task is implemented.
@@ -0,0 +1,280 @@
 package api
 import (
 	"encoding/json"
 	"fmt"
 	"io"
 	"net/http"
 	"net/http/httptest"
 	"strings"
 	"testing"
 	"time"
 )
 // Every test fetches only from local httptest servers or internal.test (fake DNS): no test
 // touches the network. newBatchServer, pageServer and fakeDNS come from batchrun_test.go.
 func batchReq(t *testing.T, s *Server, method, path, key string, body any) *httptest.ResponseRecorder {
 	t.Helper()
 	var rd io.Reader
 	if body != nil {
 		b, err := json.Marshal(body)
 		if err != nil {
 			t.Fatal(err)
 		}
 		rd = strings.NewReader(string(b))
 	}
 	req := httptest.NewRequest(method, path, rd)
 	req.Header.Set("Authorization", "Bearer "+key)
 	if body != nil {
 		req.Header.Set("Content-Type", "application/json")
 	}
 	rec := httptest.NewRecorder()
 	s.ServeHTTP(rec, req)
 	return rec
 }
 func batchDecode(t *testing.T, rec *httptest.ResponseRecorder) map[string]any {
 	t.Helper()
 	var m map[string]any
 	if err := json.Unmarshal(rec.Body.Bytes(), &m); err != nil {
 		t.Fatalf("decode: %v (%d %s)", err, rec.Code, rec.Body.String())
 	}
 	return m
 }
 func submit(t *testing.T, s *Server, key string, targets ...map[string]any) map[string]any {
 	t.Helper()
 	rec := batchReq(t, s, http.MethodPost, "/v1/batch", key, map[string]any{"targets": targets})
 	if rec.Code != 202 {
 		t.Fatalf("submit: %d %s", rec.Code, rec.Body.String())
 	}
 	return batchDecode(t, rec)
 }
 func waitTerminal(t *testing.T, s *Server, key, id string) map[string]any {
 	t.Helper()
 	deadline := time.Now().Add(10 * time.Second)
 	for time.Now().Before(deadline) {
 		env := batchDecode(t, batchReq(t, s, http.MethodGet, "/v1/batch/"+id, key, nil))
 		switch env["status"] {
 		case "done", "partial", "failed", "cancelled":
 			return env
 		}
 		time.Sleep(5 * time.Millisecond)
 	}
 	t.Fatal("batch never reached a terminal status")
 	return nil
 }
 func TestBatchSubmitAndCollect(t *testing.T) {
 	ts := pageServer(t, nil)
 	s, keys := newBatchServer(t, "test")
 	sub := submit(t, s, keys["test"], map[string]any{"url": ts.URL + "/one"}, map[string]any{"url": ts.URL + "/two"})
 	id, _ := sub["job_id"].(string)
 	if sub["success"] != true || id == "" || sub["reused"] != false || sub["targets"] != float64(2) || sub["status"] != "queued" {
 		t.Fatalf("submit body %v", sub)
 	}
 	// The status body is a summary: statuses, no results.
 	env := waitTerminal(t, s, keys["test"], id)
 	if env["status"] != "done" || env["targets_total"] != float64(2) || env["targets_done"] != float64(2) {
 		t.Fatalf("status %v", env)
 	}
 	if _, err := time.Parse(time.RFC3339, fmt.Sprint(env["created_at"])); err != nil {
 		t.Fatalf("created_at %v is not RFC 3339", env["created_at"])
 	}
 	targets := env["targets"].([]any)
 	if len(targets) != 2 {
 		t.Fatalf("targets %d", len(targets))
 	}
 	for i, x := range targets {
 		tg := x.(map[string]any)
 		if tg["idx"] != float64(i) || tg["status"] != "done" {
 			t.Fatalf("target %d: %v", i, tg)
 		}
 		if _, has := tg["result"]; has {
 			t.Fatalf("summary must not carry results: target %d has one", i)
 		}
 	}
 	// One target's result: the /v1/fetch envelope.
 	rec := batchReq(t, s, http.MethodGet, "/v1/batch/"+id+"/1", keys["test"], nil)
 	if rec.Code != 200 {
 		t.Fatalf("GET idx: %d %s", rec.Code, rec.Body.String())
 	}
 	one := batchDecode(t, rec)
 	res, _ := one["result"].(map[string]any)
 	if one["idx"] != float64(1) || one["status"] != "done" || res == nil {
 		t.Fatalf("GET idx body %v", one)
 	}
 	if c, _ := res["content"].(string); !strings.Contains(c, "hello batch /two") {
 		t.Fatalf("result content %q", c)
 	}
 	if res["untrusted"] != true || res["mode"] != "clean" {
 		t.Fatalf("result is not the /v1/fetch envelope: %v", res)
 	}
 	if src, _ := res["source"].(map[string]any); src == nil || src["final_url"] != ts.URL+"/two" {
 		t.Fatalf("result source %v", res["source"])
 	}
 	// ?results=1 inlines every result.
 	full := batchDecode(t, batchReq(t, s, http.MethodGet, "/v1/batch/"+id+"?results=1", keys["test"], nil))
 	for i, x := range full["targets"].([]any) {
 		if _, has := x.(map[string]any)["result"]; !has {
 			t.Fatalf("results=1: target %d has no result", i)
 		}
 	}
 	if got := batchReq(t, s, http.MethodGet, "/v1/batch/"+id+"/2", keys["test"], nil).Code; got != 404 {
 		t.Fatalf("GET idx out of range: %d, want 404", got)
 	}
 	if got := batchReq(t, s, http.MethodGet, "/v1/batch/"+id+"/x", keys["test"], nil).Code; got != 404 {
 		t.Fatalf("GET idx not a number: %d, want 404", got)
 	}
 }
 func TestBatchIdempotentResubmit(t *testing.T) {
 	ts := pageServer(t, nil)
 	s, keys := newBatchServer(t, "test")
 	tg := map[string]any{"url": ts.URL, "mode": "clean"}
 	a := submit(t, s, keys["test"], tg)
 	b := submit(t, s, keys["test"], tg)
 	if a["job_id"] != b["job_id"] || b["reused"] != true {
 		t.Fatalf("resubmit: %v then %v", a, b)
 	}
 }
 func TestBatchRefusedUpFront(t *testing.T) {
 	s, keys := newBatchServer(t, "test")
 	cases := []struct {
 		name string
 		body any
 		code int
 		want string
 	}{
 		{"guard pre-check (port)", map[string]any{"targets": []any{map[string]any{"url": "http://127.0.0.1/"}, map[string]any{"url": "http://example.com:8080/"}}}, 422, "blocked"},
 		{"guard pre-check (private literal)", map[string]any{"targets": []any{map[string]any{"url": "http://10.0.0.5/"}}}, 422, "blocked"},
 		{"no targets", map[string]any{"targets": []any{}}, 400, ""},
 		{"not json", "nope", 400, ""},
 		{"empty url", map[string]any{"targets": []any{map[string]any{"url": ""}}}, 400, ""},
 		{"bad mode", map[string]any{"targets": []any{map[string]any{"url": "http://127.0.0.1/", "mode": "shout"}}}, 400, ""},
 	}
 	for _, c := range cases {
 		rec := batchReq(t, s, http.MethodPost, "/v1/batch", keys["test"], c.body)
 		if rec.Code != c.code || !strings.Contains(rec.Body.String(), c.want) {
 			t.Errorf("%s: %d %s, want %d containing %q", c.name, rec.Code, rec.Body.String(), c.code, c.want)
 		}
 	}
 	// The guard refusal names the offending index.
 	rec := batchReq(t, s, http.MethodPost, "/v1/batch", keys["test"], cases[0].body)
 	if !strings.Contains(rec.Body.String(), "1") {
 		t.Errorf("guard refusal does not name target 1: %s", rec.Body.String())
 	}
 	var many []any
 	for i := 0; i < 33; i++ {
 		many = append(many, map[string]any{"url": fmt.Sprintf("http://127.0.0.1/%d", i)})
 	}
 	if rec := batchReq(t, s, http.MethodPost, "/v1/batch", keys["test"], map[string]any{"targets": many}); rec.Code != 422 {
 		t.Errorf("33 targets: %d, want 422", rec.Code)
 	}
 }
 // 32 targets, each with a 500-rune question, fit the batch body cap even though they are well
 // over the 64 KiB cap of the other endpoints.
 func TestBatchBodyCap(t *testing.T) {
 	hold := make(chan struct{})
 	defer close(hold)
 	ts := pageServer(t, hold)
 	s, keys := newBatchServer(t, "test")
 	q := strings.Repeat("q", 500)
 	var many []any
 	for i := 0; i < 32; i++ {
 		many = append(many, map[string]any{"url": fmt.Sprintf("%s/%d?pad=%s", ts.URL, i, strings.Repeat("p", 1500)), "question": q})
 	}
 	if rec := batchReq(t, s, http.MethodPost, "/v1/batch", keys["test"], map[string]any{"targets": many}); rec.Code != 202 {
 		t.Fatalf("32 targets with questions (~%d KiB): %d %s", 32*2100/1024, rec.Code, rec.Body.String())
 	}
 }
 func TestBatchPartialFailure(t *testing.T) {
 	ts := pageServer(t, nil)
 	s, keys := newBatchServer(t, "test")
 	// Target 1 is a name that resolves to a private address. Names are not resolved at submit,
 	// so it passes the pre-check; the fetch-time guard blocks it: a per-target failure.
 	sub := submit(t, s, keys["test"], map[string]any{"url": ts.URL}, map[string]any{"url": "http://internal.test/"})
 	env := waitTerminal(t, s, keys["test"], sub["job_id"].(string))
 	if env["status"] != "partial" {
 		t.Fatalf("status %v", env["status"])
 	}
 	second := env["targets"].([]any)[1].(map[string]any)
 	if second["status"] != "failed" {
 		t.Fatalf("target 1: %v", second)
 	}
 	if e, _ := second["error"].(string); !strings.Contains(e, "blocked") {
 		t.Fatalf("target 1 error %q", e)
 	}
 }
 func TestBatchOwnership404(t *testing.T) {
 	hold := make(chan struct{})
 	defer close(hold)
 	ts := pageServer(t, hold)
 	s, keys := newBatchServer(t, "test", "other")
 	id := submit(t, s, keys["test"], map[string]any{"url": ts.URL})["job_id"].(string)
 	for _, p := range []string{"/v1/batch/" + id, "/v1/batch/" + id + "/0"} {
 		if got := batchReq(t, s, http.MethodGet, p, keys["other"], nil).Code; got != 404 {
 			t.Fatalf("other caller GET %s: %d (must not reveal the job)", p, got)
 		}
 	}
 	if got := batchReq(t, s, http.MethodDelete, "/v1/batch/"+id, keys["other"], nil).Code; got != 404 {
 		t.Fatalf("other caller DELETE: %d", got)
 	}
 	if got := batchReq(t, s, http.MethodGet, "/v1/batch/"+id, keys["test"], nil).Code; got != 200 {
 		t.Fatalf("owner GET: %d", got)
 	}
 	if got := batchReq(t, s, http.MethodGet, "/v1/batch/no-such-job", keys["test"], nil).Code; got != 404 {
 		t.Fatalf("unknown job: %d", got)
 	}
 	if got := batchReq(t, s, http.MethodGet, "/v1/batch/"+id, "not-a-key", nil).Code; got != 401 {
 		t.Fatalf("bad key: %d", got)
 	}
 }
 func TestBatchCancel(t *testing.T) {
 	hold := make(chan struct{})
 	ts := pageServer(t, hold)
 	s, keys := newBatchServer(t, "test")
 	id := submit(t, s, keys["test"], map[string]any{"url": ts.URL + "/a"}, map[string]any{"url": ts.URL + "/b"})["job_id"].(string)
 	rec := batchReq(t, s, http.MethodDelete, "/v1/batch/"+id, keys["test"], nil)
 	if rec.Code != 200 {
 		t.Fatalf("cancel: %d %s", rec.Code, rec.Body.String())
 	}
 	if b := batchDecode(t, rec); b["success"] != true || b["status"] != "cancelled" {
 		t.Fatalf("cancel body %v", b)
 	}
 	close(hold)
 	env := waitTerminal(t, s, keys["test"], id)
 	if env["status"] != "cancelled" {
 		t.Fatalf("status %v", env["status"])
 	}
 	if tg := env["targets"].([]any)[1].(map[string]any); tg["status"] != "pending" {
 		t.Fatalf("target 1 after cancel: %v", tg)
 	}
 	if got := batchReq(t, s, http.MethodDelete, "/v1/batch/"+id, keys["test"], nil).Code; got != 409 {
 		t.Fatalf("cancelling a finished job: %d, want 409", got)
 	}
 }
 // The request metrics never get a job id as a label value.
 func TestBatchMetricsPathLabel(t *testing.T) {
 	ts := pageServer(t, nil)
 	s, keys := newBatchServer(t, "test")
 	id := submit(t, s, keys["test"], map[string]any{"url": ts.URL})["job_id"].(string)
 	waitTerminal(t, s, keys["test"], id)
 	batchReq(t, s, http.MethodGet, "/v1/batch/"+id+"/0", keys["test"], nil)
 	if strings.Contains(promText(t, s), id) {
 		t.Fatal("a job id appears in /metrics")
 	}
 }
@@ -0,0 +1,202 @@
 package api
 // P6 task 05: the runner wired to fetchTarget and the metrics, with no HTTP yet. The helpers
 // here (newBatchServer, pageServer, fakeDNS) are shared with task 06's batch_test.go.
 import (
 	"context"
 	"errors"
 	"fmt"
 	"io"
 	"log/slog"
 	"net/http"
 	"net/http/httptest"
 	"net/netip"
 	"os"
 	"path/filepath"
 	"strings"
 	"testing"
 	"time"
 	"git.wntrmute.dev/kyle/sift/internal/auth"
 	"git.wntrmute.dev/kyle/sift/internal/batch"
 	"git.wntrmute.dev/kyle/sift/internal/dcache"
 	"git.wntrmute.dev/kyle/sift/internal/fetch"
 	"git.wntrmute.dev/kyle/sift/internal/guard"
 )
 var loopback = []netip.Prefix{netip.MustParsePrefix("127.0.0.0/8")}
 // fakeDNS resolves internal.test to a private address; every other name fails to resolve.
 func fakeDNS(_ context.Context, host string) ([]netip.Addr, error) {
 	if host == "internal.test" {
 		return []netip.Addr{netip.MustParseAddr("10.0.0.5")}, nil
 	}
 	return nil, fmt.Errorf("no such host %s", host)
 }
 // newBatchServer builds a Server with the batch runner wired over an in-memory dcache through
 // s.NewBatchRunner, exactly as serve does. callers are the names to provision (each gets a key).
 func newBatchServer(t *testing.T, callers ...string) (*Server, map[string]string) {
 	t.Helper()
 	dir := t.TempDir()
 	keysPath := filepath.Join(dir, "keys.toml")
 	keys := map[string]string{}
 	for _, name := range callers {
 		out := filepath.Join(dir, name)
 		if err := auth.Add(keysPath, name, "hermes-fleet", out); err != nil {
 			t.Fatal(err)
 		}
 		b, err := os.ReadFile(out)
 		if err != nil {
 			t.Fatal(err)
 		}
 		keys[name] = strings.TrimSpace(string(b))
 	}
 	store, err := auth.Load(keysPath)
 	if err != nil {
 		t.Fatal(err)
 	}
 	g := &guard.Guard{AllowPrefixes: loopback, LookupIP: fakeDNS}
 	f := &fetch.Fetcher{Guard: g, UA: "sift-test"}
 	log := slog.New(slog.NewTextHandler(io.Discard, nil))
 	s := New("test", g, f, store, log)
 	db, err := dcache.Open("", 1<<20, log)
 	if err != nil {
 		t.Fatal(err)
 	}
 	t.Cleanup(func() { _ = db.Close() })
 	s.Batch = s.NewBatchRunner(db, batch.Config{})
 	t.Cleanup(s.Batch.Close) // before db.Close
 	return s, keys
 }
 // pageServer serves a small HTML page at every path; hold, when non-nil, blocks each request
 // until it is closed.
 func pageServer(t *testing.T, hold chan struct{}) *httptest.Server {
 	t.Helper()
 	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		if hold != nil {
 			select {
 			case <-hold:
 			case <-r.Context().Done():
 				return
 			}
 		}
 		w.Header().Set("Content-Type", "text/html; charset=utf-8")
 		fmt.Fprintf(w, `<html><head><title>T</title></head><body><article><p>hello batch %s</p></article></body></html>`, r.URL.Path)
 	}))
 	t.Cleanup(ts.Close)
 	return ts
 }
 func waitJob(t *testing.T, r *batch.Runner, id string) batch.Job {
 	t.Helper()
 	deadline := time.Now().Add(10 * time.Second)
 	for time.Now().Before(deadline) {
 		j, _, ok := r.Status(id)
 		if ok && (j.Status == "done" || j.Status == "partial" || j.Status == "failed" || j.Status == "cancelled") {
 			return j
 		}
 		time.Sleep(5 * time.Millisecond)
 	}
 	t.Fatal("job never finished")
 	return batch.Job{}
 }
 func promText(t *testing.T, s *Server) string {
 	t.Helper()
 	req := httptest.NewRequest(http.MethodGet, "/metrics", nil)
 	req.RemoteAddr, req.Host = "127.0.0.1:9", "127.0.0.1:8890"
 	rec := httptest.NewRecorder()
 	s.ServeHTTP(rec, req)
 	return rec.Body.String()
 }
 // The runner fetches through fetchTarget as the submitting caller; a name that resolves to a
 // private address is a per-target "blocked" failure; the hooks reach the metrics.
 func TestBatchRunnerWired(t *testing.T) {
 	ts := pageServer(t, nil)
 	s, _ := newBatchServer(t, "test")
 	c := &auth.Caller{Name: "test", Workspace: "hermes-fleet"}
 	id, reused, err := s.Batch.Submit(context.Background(), c, dcache.ClassFleet, []batch.Target{
 		{URL: ts.URL + "/one"}, {URL: "http://internal.test/"},
 	})
 	if err != nil || reused {
 		t.Fatalf("submit: %v %v", err, reused)
 	}
 	if j := waitJob(t, s.Batch, id); j.Status != "partial" {
 		t.Fatalf("job %+v", j)
 	}
 	_, ts2, _ := s.Batch.Status(id)
 	if ts2[0].Status != "done" || ts2[0].Result == nil || !strings.Contains(ts2[0].Result.Content, "hello batch /one") {
 		t.Fatalf("target 0: %+v", ts2[0])
 	}
 	if ts2[0].Result.Meta["mode"] != "clean" || ts2[0].Result.Meta["untrusted"] != true {
 		t.Fatalf("target 0 meta %v: not the fetchTarget envelope", ts2[0].Result.Meta)
 	}
 	if ts2[1].Status != "failed" || !strings.Contains(ts2[1].Error, "blocked") {
 		t.Fatalf("target 1: %+v", ts2[1])
 	}
 	out := promText(t, s)
 	for _, want := range []string{
 		`sift_batch_jobs_total{outcome="created"} 1`,
 		`sift_batch_jobs_total{outcome="partial"} 1`,
 		`sift_batch_targets_total{outcome="ok"} 1`,
 		`sift_batch_targets_total{outcome="blocked"} 1`,
 		`sift_batch_result_bytes_count 1`,
 		`sift_batch_queue_depth 0`,
 	} {
 		if !strings.Contains(out, want) {
 			t.Errorf("metrics lack %q", want)
 		}
 	}
 }
 // The adapter turns fetch errors into what the runner and the metrics need.
 func TestBatchOutcomeClasses(t *testing.T) {
 	cases := []struct {
 		err  error
 		want string
 	}{
 		{nil, "ok"},
 		{fmt.Errorf("busy: %w", batch.ErrRetryLater), "busy"},
 		{&batch.TargetError{Status: 403, Msg: "blocked: private address"}, "blocked"},
 		{&batch.TargetError{Status: 429, Msg: "busy"}, "busy"},
 		{&batch.TargetError{Status: 504, Msg: "timeout"}, "timeout"},
 		{&batch.TargetError{Status: 415, Msg: "unsupported content type"}, "unsupported"},
 		{&batch.TargetError{Status: 422, Msg: "document too long for question (6001 chunks); use grep or pages"}, "too_long"},
 		{&batch.TargetError{Status: 422, Msg: "unreadable PDF"}, "upstream_4xx"},
 		{&batch.TargetError{Status: 404, Msg: "not found"}, "upstream_4xx"},
 		{&batch.TargetError{Status: 500, Msg: "internal error"}, "upstream_5xx"},
 		{errors.New("something else"), "upstream_5xx"},
 	}
 	for _, c := range cases {
 		if got := batchOutcome(c.err); got != c.want {
 			t.Errorf("batchOutcome(%v) = %q, want %q", c.err, got, c.want)
 		}
 	}
 }
 // batchFetch maps a busy fetch to ErrRetryLater (the runner retries it) and every other
 // failure to a TargetError with the /v1/fetch status.
 func TestBatchFetchErrors(t *testing.T) {
 	s, _ := newBatchServer(t, "test")
 	c := &auth.Caller{Name: "test", Workspace: "hermes-fleet"}
 	_, err := s.batchFetch(context.Background(), c, batch.Target{URL: "http://internal.test/"})
 	var te *batch.TargetError
 	if !errors.As(err, &te) || te.Status != 403 || !strings.Contains(te.Msg, "blocked") {
 		t.Fatalf("private name: %v, want a TargetError 403 blocked", err)
 	}
 	// Fill the global fetch gate so the next fetch is refused busy.
 	for i := 0; i < 8; i++ {
 		if err := s.acquire(fmt.Sprintf("filler%d", i), "http://filler.test/"); err != nil {
 			t.Fatal(err)
 		}
 	}
 	ts := pageServer(t, nil)
 	_, err = s.batchFetch(context.Background(), c, batch.Target{URL: ts.URL})
 	if !errors.Is(err, batch.ErrRetryLater) {
 		t.Fatalf("busy gate: %v, want an error wrapping batch.ErrRetryLater", err)
 	}
 }
@@ -0,0 +1,94 @@
 package api
 // P6 task 04: v1fetch's per-target pipeline is extracted into s.fetchTarget, which the batch
 // runner also calls. These tests pin that the two agree; every existing v1fetch test must also
 // pass unchanged.
 import (
 	"context"
 	"encoding/json"
 	"errors"
 	"net/http"
 	"net/http/httptest"
 	"net/netip"
 	"strings"
 	"testing"
 	"git.wntrmute.dev/kyle/sift/internal/auth"
 	"git.wntrmute.dev/kyle/sift/internal/batch"
 	"git.wntrmute.dev/kyle/sift/internal/fetch"
 	"git.wntrmute.dev/kyle/sift/internal/guard"
 )
 // newTargetServer is setupAPI with loopback allowed; its key belongs to caller "test".
 func newTargetServer(t *testing.T) (*Server, string) {
 	t.Helper()
 	return setupAPI(t, &guard.Guard{AllowPrefixes: []netip.Prefix{netip.MustParsePrefix("127.0.0.0/8")}})
 }
 func TestFetchTargetMatchesV1Fetch(t *testing.T) {
 	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
 		w.Header().Set("Content-Type", "text/html; charset=utf-8")
 		_, _ = w.Write([]byte(`<html><head><title>Same</title></head><body><article><h1>Same</h1><p>one pipeline, two callers</p></article></body></html>`))
 	}))
 	defer ts.Close()
 	s, key := newTargetServer(t)
 	c := &auth.Caller{Name: "test", Workspace: "hermes-fleet"}
 	res, err := s.fetchTarget(context.Background(), c, batch.Target{URL: ts.URL})
 	if err != nil {
 		t.Fatal(err)
 	}
 	if !strings.Contains(res.Content, "one pipeline, two callers") {
 		t.Fatalf("content %q", res.Content)
 	}
 	if _, has := res.Meta["content"]; has {
 		t.Fatal("Meta must not repeat the content")
 	}
 	for _, k := range []string{"mode", "untrusted", "source", "warnings", "sizes", "timings"} {
 		if _, has := res.Meta[k]; !has {
 			t.Errorf("Meta lacks %q (it carries every envelope field except content)", k)
 		}
 	}
 	if res.Meta["mode"] != "clean" || res.Meta["untrusted"] != true {
 		t.Fatalf("meta %v", res.Meta)
 	}
 	// The same URL through /v1/fetch: identical content and mode, and the envelope has exactly
 	// the fields of Meta plus content.
 	rec := postJSON(t, s, "/v1/fetch", key, map[string]any{"url": ts.URL})
 	if rec.Code != 200 {
 		t.Fatalf("v1fetch %d %s", rec.Code, rec.Body.String())
 	}
 	var env map[string]any
 	if err := json.Unmarshal(rec.Body.Bytes(), &env); err != nil {
 		t.Fatal(err)
 	}
 	if env["content"] != res.Content || env["mode"] != res.Meta["mode"] {
 		t.Fatalf("v1fetch and fetchTarget disagree:\n%v\n%+v", env, res)
 	}
 	if len(env) != len(res.Meta)+1 {
 		t.Fatalf("envelope keys %d, Meta keys %d: want Meta + content", len(env), len(res.Meta))
 	}
 }
 func TestFetchTargetErrors(t *testing.T) {
 	s, _ := newTargetServer(t)
 	c := &auth.Caller{Name: "test", Workspace: "hermes-fleet"}
 	cases := []struct {
 		name   string
 		target batch.Target
 		status int
 		msg    string
 	}{
 		{"blocked", batch.Target{URL: "http://10.0.0.5/"}, 403, "blocked"},
 		{"bad mode", batch.Target{URL: "http://127.0.0.1/", Options: batch.Options{Mode: "shout"}}, 400, ""},
 	}
 	for _, tc := range cases {
 		_, err := s.fetchTarget(context.Background(), c, tc.target)
 		var fe *fetch.Error
 		if !errors.As(err, &fe) || fe.Status != tc.status || !strings.Contains(fe.Msg, tc.msg) {
 			t.Errorf("%s: err %v, want a *fetch.Error %d containing %q", tc.name, err, tc.status, tc.msg)
 		}
 	}
 }
@@ -0,0 +1,452 @@
 package batch
 import (
 	"context"
 	"errors"
 	"fmt"
 	"io"
 	"log/slog"
 	"strings"
 	"sync"
 	"testing"
 	"time"
 	"git.wntrmute.dev/kyle/sift/internal/auth"
 	"git.wntrmute.dev/kyle/sift/internal/dcache"
 )
 var (
 	alice = &auth.Caller{Name: "alice", Workspace: "hermes-fleet"}
 	bob   = &auth.Caller{Name: "bob", Workspace: "hermes-fleet"}
 	carol = &auth.Caller{Name: "carol", Workspace: "hermes-fleet"}
 )
 func newRunner(t *testing.T, fetch FetchFunc, cfg Config) *Runner {
 	t.Helper()
 	db, err := dcache.Open("", 1<<20, slog.New(slog.NewTextHandler(io.Discard, nil)))
 	if err != nil {
 		t.Fatal(err)
 	}
 	t.Cleanup(func() { _ = db.Close() })
 	r := New(db, fetch, cfg, slog.New(slog.NewTextHandler(io.Discard, nil)))
 	t.Cleanup(r.Close) // runs before db.Close (cleanups are LIFO)
 	return r
 }
 func waitStatus(t *testing.T, r *Runner, id, want string) {
 	t.Helper()
 	deadline := time.Now().Add(5 * time.Second)
 	for time.Now().Before(deadline) {
 		j, _, ok := r.Status(id)
 		if ok && j.Status == want {
 			return
 		}
 		time.Sleep(2 * time.Millisecond)
 	}
 	j, _, _ := r.Status(id)
 	t.Fatalf("job %s never reached %q (now %q)", id, want, j.Status)
 }
 func urls(ss ...string) []Target {
 	var out []Target
 	for _, s := range ss {
 		out = append(out, Target{URL: "https://" + s + ".example/"})
 	}
 	return out
 }
 // Targets run one at a time, in order, and each fetch is given the submitting caller.
 func TestSerialOrderAndCaller(t *testing.T) {
 	var mu sync.Mutex
 	var calls, names []string
 	inflight, peak := 0, 0
 	fetch := func(_ context.Context, c *auth.Caller, tgt Target) (Result, error) {
 		mu.Lock()
 		inflight++
 		if inflight > peak {
 			peak = inflight
 		}
 		calls = append(calls, tgt.URL)
 		names = append(names, c.Name)
 		mu.Unlock()
 		time.Sleep(time.Millisecond)
 		mu.Lock()
 		inflight--
 		mu.Unlock()
 		return Result{Content: "ok " + tgt.URL}, nil
 	}
 	r := newRunner(t, fetch, Config{})
 	id, reused, err := r.Submit(context.Background(), alice, dcache.ClassFleet, urls("a", "b", "c"))
 	if err != nil || reused {
 		t.Fatalf("submit err=%v reused=%v", err, reused)
 	}
 	waitStatus(t, r, id, "done")
 	mu.Lock()
 	defer mu.Unlock()
 	if strings.Join(calls, " ") != "https://a.example/ https://b.example/ https://c.example/" {
 		t.Fatalf("order %v", calls)
 	}
 	if peak != 1 {
 		t.Fatalf("peak inflight %d, want 1 (serial)", peak)
 	}
 	for _, n := range names {
 		if n != "alice" {
 			t.Fatalf("fetch saw caller %q, want alice", n)
 		}
 	}
 	j, _, _ := r.Status(id)
 	if j.Caller != "alice" || j.TargetsTotal != 3 || j.TargetsDone != 3 || j.CreatedAt == 0 {
 		t.Fatalf("job %+v", j)
 	}
 }
 // With one worker, two live jobs take turns target by target.
 func TestRoundRobin(t *testing.T) {
 	first := make(chan struct{})
 	release := make(chan struct{})
 	var once sync.Once
 	var mu sync.Mutex
 	var calls []string
 	fetch := func(_ context.Context, _ *auth.Caller, tgt Target) (Result, error) {
 		mu.Lock()
 		calls = append(calls, strings.TrimSuffix(strings.TrimPrefix(tgt.URL, "https://"), ".example/"))
 		mu.Unlock()
 		once.Do(func() { close(first); <-release })
 		return Result{Content: "ok"}, nil
 	}
 	r := newRunner(t, fetch, Config{Workers: 1})
 	a, _, err := r.Submit(context.Background(), alice, dcache.ClassFleet, urls("a1", "a2", "a3"))
 	if err != nil {
 		t.Fatal(err)
 	}
 	<-first // a1 is in flight
 	b, _, err := r.Submit(context.Background(), bob, dcache.ClassFleet, urls("b1", "b2", "b3"))
 	if err != nil {
 		t.Fatal(err)
 	}
 	close(release)
 	waitStatus(t, r, a, "done")
 	waitStatus(t, r, b, "done")
 	mu.Lock()
 	defer mu.Unlock()
 	if got := strings.Join(calls, " "); got != "a1 b1 a2 b2 a3 b3" {
 		t.Fatalf("order %q, want round-robin a1 b1 a2 b2 a3 b3", got)
 	}
 }
 func TestFailureIsolation(t *testing.T) {
 	fetch := func(_ context.Context, _ *auth.Caller, tgt Target) (Result, error) {
 		if tgt.URL == "https://b.example/" {
 			return Result{}, &TargetError{Msg: "upstream 500", Hint: "browser"}
 		}
 		return Result{Content: "ok " + tgt.URL}, nil
 	}
 	r := newRunner(t, fetch, Config{})
 	id, _, err := r.Submit(context.Background(), alice, dcache.ClassFleet, urls("a", "b", "c"))
 	if err != nil {
 		t.Fatal(err)
 	}
 	waitStatus(t, r, id, "partial")
 	j, ts, ok := r.Status(id)
 	if !ok || j.TargetsDone != 3 {
 		t.Fatalf("job %+v ok=%v", j, ok)
 	}
 	if ts[0].Status != "done" || ts[1].Status != "failed" || ts[2].Status != "done" {
 		t.Fatalf("statuses %+v", ts)
 	}
 	if ts[1].Error != "upstream 500" || ts[1].Hint != "browser" {
 		t.Fatalf("failed target error=%q hint=%q", ts[1].Error, ts[1].Hint)
 	}
 	if ts[0].Result == nil || ts[0].Result.Content != "ok https://a.example/" {
 		t.Fatalf("result %+v", ts[0].Result)
 	}
 }
 func TestAllFailedIsFailed(t *testing.T) {
 	fetch := func(context.Context, *auth.Caller, Target) (Result, error) { return Result{}, errors.New("nope") }
 	r := newRunner(t, fetch, Config{})
 	id, _, err := r.Submit(context.Background(), alice, dcache.ClassFleet, urls("a", "b"))
 	if err != nil {
 		t.Fatal(err)
 	}
 	waitStatus(t, r, id, "failed")
 	_, ts, _ := r.Status(id)
 	if ts[0].Error != "nope" || ts[0].Hint != "" {
 		t.Fatalf("plain error stored as error=%q hint=%q", ts[0].Error, ts[0].Hint)
 	}
 }
 func TestIdempotentResubmit(t *testing.T) {
 	var mu sync.Mutex
 	n := 0
 	fetch := func(context.Context, *auth.Caller, Target) (Result, error) {
 		mu.Lock()
 		n++
 		mu.Unlock()
 		return Result{Content: "ok"}, nil
 	}
 	r := newRunner(t, fetch, Config{})
 	id1, reused1, err := r.Submit(context.Background(), alice, dcache.ClassFleet, urls("a", "b"))
 	if err != nil || reused1 {
 		t.Fatalf("first submit err=%v reused=%v", err, reused1)
 	}
 	id2, reused2, err := r.Submit(context.Background(), alice, dcache.ClassFleet, urls("a", "b"))
 	if err != nil || !reused2 || id2 != id1 {
 		t.Fatalf("resubmit id=%q reused=%v err=%v", id2, reused2, err)
 	}
 	waitStatus(t, r, id1, "done")
 	// Still reused once done (within the lease), and never re-fetched.
 	if id3, reused3, err := r.Submit(context.Background(), alice, dcache.ClassFleet, urls("a", "b")); err != nil || !reused3 || id3 != id1 {
 		t.Fatalf("resubmit after done id=%q reused=%v err=%v", id3, reused3, err)
 	}
 	// Another caller with the same list gets its own job.
 	if id4, reused4, err := r.Submit(context.Background(), bob, dcache.ClassFleet, urls("a", "b")); err != nil || reused4 || id4 == id1 {
 		t.Fatalf("other caller id=%q reused=%v err=%v", id4, reused4, err)
 	}
 	time.Sleep(50 * time.Millisecond)
 	mu.Lock()
 	defer mu.Unlock()
 	if n != 4 {
 		t.Fatalf("fetched %d times, want 4 (2 for alice's one job, 2 for bob's)", n)
 	}
 }
 // A cancelled job is not handed back to a resubmit: the same list starts a new job.
 func TestResubmitAfterCancelIsNew(t *testing.T) {
 	release := make(chan struct{})
 	fetch := func(context.Context, *auth.Caller, Target) (Result, error) {
 		<-release
 		return Result{Content: "ok"}, nil
 	}
 	r := newRunner(t, fetch, Config{})
 	id1, _, err := r.Submit(context.Background(), alice, dcache.ClassFleet, urls("a", "b"))
 	if err != nil {
 		t.Fatal(err)
 	}
 	waitStatus(t, r, id1, "running")
 	if !r.Cancel(id1) {
 		t.Fatal("cancel returned false")
 	}
 	close(release)
 	waitStatus(t, r, id1, "cancelled")
 	id2, reused, err := r.Submit(context.Background(), alice, dcache.ClassFleet, urls("a", "b"))
 	if err != nil || reused || id2 == id1 {
 		t.Fatalf("resubmit after cancel id=%q reused=%v err=%v", id2, reused, err)
 	}
 }
 func TestCaps(t *testing.T) {
 	release := make(chan struct{})
 	fetch := func(context.Context, *auth.Caller, Target) (Result, error) {
 		<-release
 		return Result{Content: "ok"}, nil
 	}
 	r := newRunner(t, fetch, Config{TargetsPerJob: 2, JobsTotal: 2})
 	defer close(release)
 	if _, _, err := r.Submit(context.Background(), alice, dcache.ClassFleet, urls("a", "b", "c")); !errors.Is(err, ErrTooManyTargets) {
 		t.Fatalf("3 targets over a cap of 2: want ErrTooManyTargets, got %v", err)
 	}
 	if _, _, err := r.Submit(context.Background(), alice, dcache.ClassFleet, nil); !errors.Is(err, ErrNoTargets) {
 		t.Fatalf("no targets: want ErrNoTargets, got %v", err)
 	}
 	if _, _, err := r.Submit(context.Background(), alice, dcache.ClassFleet, urls("a")); err != nil {
 		t.Fatal(err)
 	}
 	// alice's job is live (queued or running): a second, different list is refused.
 	if _, _, err := r.Submit(context.Background(), alice, dcache.ClassFleet, urls("z")); !errors.Is(err, ErrCallerBusy) {
 		t.Fatalf("want ErrCallerBusy, got %v", err)
 	}
 	if _, _, err := r.Submit(context.Background(), bob, dcache.ClassFleet, urls("b")); err != nil {
 		t.Fatal(err)
 	}
 	// Two live jobs in total: a third caller is refused.
 	if _, _, err := r.Submit(context.Background(), carol, dcache.ClassFleet, urls("c")); !errors.Is(err, ErrBusy) {
 		t.Fatalf("want ErrBusy, got %v", err)
 	}
 }
 // Submit returns with the job stored "queued"; it becomes "running" when a worker takes it.
 func TestQueuedThenRunning(t *testing.T) {
 	release := make(chan struct{})
 	fetch := func(context.Context, *auth.Caller, Target) (Result, error) {
 		<-release
 		return Result{Content: "ok"}, nil
 	}
 	r := newRunner(t, fetch, Config{Workers: 1})
 	defer close(release)
 	a, _, _ := r.Submit(context.Background(), alice, dcache.ClassFleet, urls("a"))
 	waitStatus(t, r, a, "running")
 	b, _, err := r.Submit(context.Background(), bob, dcache.ClassFleet, urls("b"))
 	if err != nil {
 		t.Fatal(err)
 	}
 	// The only worker is busy with alice's target, so bob's job waits in the queue.
 	time.Sleep(20 * time.Millisecond)
 	if j, _, _ := r.Status(b); j.Status != "queued" {
 		t.Fatalf("bob's job is %q while the only worker is busy, want queued", j.Status)
 	}
 }
 func TestCancel(t *testing.T) {
 	started := make(chan struct{}, 1)
 	release := make(chan struct{})
 	var mu sync.Mutex
 	var calls []string
 	fetch := func(_ context.Context, _ *auth.Caller, tgt Target) (Result, error) {
 		mu.Lock()
 		calls = append(calls, tgt.URL)
 		mu.Unlock()
 		select {
 		case started <- struct{}{}:
 		default:
 		}
 		<-release
 		return Result{Content: "ok"}, nil
 	}
 	r := newRunner(t, fetch, Config{})
 	id, _, err := r.Submit(context.Background(), alice, dcache.ClassFleet, urls("a", "b", "c"))
 	if err != nil {
 		t.Fatal(err)
 	}
 	<-started // the first target is in flight
 	if !r.Cancel(id) {
 		t.Fatal("cancel returned false")
 	}
 	close(release) // let the in-flight target finish
 	waitStatus(t, r, id, "cancelled")
 	time.Sleep(20 * time.Millisecond)
 	mu.Lock()
 	n := len(calls)
 	mu.Unlock()
 	if n != 1 {
 		t.Fatalf("cancelled after %d fetches, want 1", n)
 	}
 	j, ts, ok := r.Status(id)
 	if !ok || j.Status != "cancelled" {
 		t.Fatalf("job %+v: the in-flight target's write must not overwrite cancelled", j)
 	}
 	if ts[0].Status != "done" {
 		t.Fatalf("in-flight target should be stored done: %+v", ts[0])
 	}
 	if ts[1].Status != "pending" || ts[2].Status != "pending" {
 		t.Fatalf("later targets must stay pending: %+v", ts[1:])
 	}
 	if r.Cancel(id) {
 		t.Fatal("cancelling a terminal job must return false")
 	}
 	if r.Cancel("no-such-job") {
 		t.Fatal("cancelling an unknown job must return false")
 	}
 }
 // A target that reports ErrRetryLater (the fetch gate was busy) is retried, not failed.
 func TestBusyIsRetried(t *testing.T) {
 	var mu sync.Mutex
 	n := 0
 	fetch := func(context.Context, *auth.Caller, Target) (Result, error) {
 		mu.Lock()
 		defer mu.Unlock()
 		n++
 		if n <= 2 {
 			return Result{}, fmt.Errorf("busy: %w", ErrRetryLater)
 		}
 		return Result{Content: "ok"}, nil
 	}
 	r := newRunner(t, fetch, Config{RetryWait: time.Millisecond})
 	id, _, err := r.Submit(context.Background(), alice, dcache.ClassFleet, urls("a"))
 	if err != nil {
 		t.Fatal(err)
 	}
 	waitStatus(t, r, id, "done")
 	mu.Lock()
 	defer mu.Unlock()
 	if n != 3 {
 		t.Fatalf("fetched %d times, want 3 (two busy, then ok)", n)
 	}
 }
 // Retrying is bounded: a target busy for longer than RetryFor fails with a busy error.
 func TestBusyGivesUp(t *testing.T) {
 	fetch := func(context.Context, *auth.Caller, Target) (Result, error) {
 		return Result{}, fmt.Errorf("busy: %w", ErrRetryLater)
 	}
 	r := newRunner(t, fetch, Config{RetryWait: time.Millisecond, RetryFor: 30 * time.Millisecond})
 	id, _, err := r.Submit(context.Background(), alice, dcache.ClassFleet, urls("a"))
 	if err != nil {
 		t.Fatal(err)
 	}
 	waitStatus(t, r, id, "failed")
 	_, ts, _ := r.Status(id)
 	if ts[0].Status != "failed" || !strings.Contains(ts[0].Error, "busy") {
 		t.Fatalf("target %+v, want failed with a busy error", ts[0])
 	}
 }
 func TestPanicRecovered(t *testing.T) {
 	fetch := func(_ context.Context, _ *auth.Caller, tgt Target) (Result, error) {
 		if tgt.URL == "https://b.example/" {
 			panic("boom")
 		}
 		return Result{Content: "ok"}, nil
 	}
 	r := newRunner(t, fetch, Config{})
 	id, _, err := r.Submit(context.Background(), alice, dcache.ClassFleet, urls("a", "b", "c"))
 	if err != nil {
 		t.Fatal(err)
 	}
 	waitStatus(t, r, id, "partial")
 	_, ts, _ := r.Status(id)
 	if ts[0].Status != "done" || ts[1].Status != "failed" || ts[2].Status != "done" {
 		t.Fatalf("statuses %+v", ts)
 	}
 	if ts[1].Error == "" || strings.Contains(ts[1].Error, "boom") {
 		t.Fatalf("panic target error %q: must be set, and must not echo the panic value", ts[1].Error)
 	}
 }
 // The hooks see every job outcome once and every stored target once.
 func TestHooks(t *testing.T) {
 	var mu sync.Mutex
 	jobs := map[string]int{}
 	var targets, jobSecs int
 	var bytes int
 	h := Hooks{
 		Job: func(o string) { mu.Lock(); jobs[o]++; mu.Unlock() },
 		Target: func(err error, _ time.Duration, n int) {
 			mu.Lock()
 			targets++
 			bytes += n
 			mu.Unlock()
 		},
 		JobSeconds: func(time.Duration) { mu.Lock(); jobSecs++; mu.Unlock() },
 	}
 	fetch := func(_ context.Context, _ *auth.Caller, tgt Target) (Result, error) {
 		if tgt.URL == "https://b.example/" {
 			return Result{}, errors.New("nope")
 		}
 		return Result{Content: "ok"}, nil
 	}
 	r := newRunner(t, fetch, Config{Hooks: h})
 	id, _, _ := r.Submit(context.Background(), alice, dcache.ClassFleet, urls("a", "b"))
 	waitStatus(t, r, id, "partial")
 	_, _, _ = r.Submit(context.Background(), alice, dcache.ClassFleet, urls("a", "b")) // reused
 	time.Sleep(20 * time.Millisecond)
 	mu.Lock()
 	defer mu.Unlock()
 	if jobs["created"] != 1 || jobs["partial"] != 1 || jobs["reused"] != 1 || len(jobs) != 3 {
 		t.Fatalf("job outcomes %v", jobs)
 	}
 	if targets != 2 || jobSecs != 1 {
 		t.Fatalf("targets=%d jobSeconds=%d, want 2 and 1", targets, jobSecs)
 	}
 	if bytes <= 0 {
 		t.Fatalf("stored result bytes %d, want > 0 for the done target", bytes)
 	}
 }
 func TestStatusUnknown(t *testing.T) {
 	r := newRunner(t, func(context.Context, *auth.Caller, Target) (Result, error) { return Result{}, nil }, Config{})
 	if _, _, ok := r.Status("no-such-job"); ok {
 		t.Fatal("unknown id must be ok=false")
 	}
 }
@@ -0,0 +1,46 @@
 package main
 import (
 	"slices"
 	"testing"
 )
 func TestParseBatchArgs(t *testing.T) {
 	cases := []struct {
 		args []string
 		verb string
 		rest []string
 		ok   bool
 	}{
 		{[]string{"submit", "targets.json"}, "submit", []string{"targets.json"}, true},
 		{[]string{"submit", "-"}, "submit", []string{"-"}, true},
 		{[]string{"status", "job-123"}, "status", []string{"job-123"}, true},
 		{[]string{"status", "--results", "job-123"}, "status", []string{"--results", "job-123"}, true},
 		{[]string{"get", "job-123", "4"}, "get", []string{"job-123", "4"}, true},
 		{[]string{"cancel", "job-123"}, "cancel", []string{"job-123"}, true},
 		{[]string{}, "", nil, false},
 		{[]string{"submit"}, "", nil, false},
 		{[]string{"status"}, "", nil, false},
 		{[]string{"status", "a", "b"}, "", nil, false},
 		{[]string{"status", "--results"}, "", nil, false},
 		{[]string{"get", "job-123"}, "", nil, false},
 		{[]string{"get", "job-123", "x"}, "", nil, false},
 		{[]string{"get", "job-123", "-1"}, "", nil, false},
 		{[]string{"cancel"}, "", nil, false},
 		{[]string{"bogus", "x"}, "", nil, false},
 	}
 	for _, c := range cases {
 		verb, rest, err := parseBatchArgs(c.args)
 		if c.ok {
 			if err != nil {
 				t.Errorf("%v: unexpected error %v", c.args, err)
 				continue
 			}
 			if verb != c.verb || !slices.Equal(rest, c.rest) {
 				t.Errorf("%v: got verb=%q rest=%q", c.args, verb, rest)
 			}
 		} else if err == nil {
 			t.Errorf("%v: want an error", c.args)
 		}
 	}
 }
@@ -0,0 +1,56 @@
 package config
 // P6 task 07: the [batch] block and ParseSize.
 import (
 	"os"
 	"path/filepath"
 	"testing"
 )
 func TestBatchBlock(t *testing.T) {
 	p := filepath.Join(t.TempDir(), "sift.toml")
 	body := "[batch]\ndisabled = false\ntargets_per_job = 16\njobs_per_caller = 2\njobs_total = 4\nworkers = 2\nttl = \"12h\"\nmax_bytes = \"32MiB\"\n"
 	if err := os.WriteFile(p, []byte(body), 0o600); err != nil {
 		t.Fatal(err)
 	}
 	f, err := Load(p)
 	if err != nil {
 		t.Fatal(err)
 	}
 	b := f.Batch
 	if b.Disabled || b.TargetsPerJob != 16 || b.JobsPerCaller != 2 || b.JobsTotal != 4 || b.Workers != 2 || b.TTL != "12h" || b.MaxBytes != "32MiB" {
 		t.Fatalf("batch block %+v", b)
 	}
 	// No block: zero values, and batch is on (the runner applies its own defaults).
 	empty := filepath.Join(t.TempDir(), "empty.toml")
 	if err := os.WriteFile(empty, []byte("listen = \":8443\"\n"), 0o600); err != nil {
 		t.Fatal(err)
 	}
 	if f, err := Load(empty); err != nil || f.Batch != (Batch{}) {
 		t.Fatalf("no [batch] block: %+v %v", f.Batch, err)
 	}
 }
 func TestParseSize(t *testing.T) {
 	const def = 7
 	for _, c := range []struct {
 		in   string
 		want int64
 	}{
 		{"64MiB", 64 << 20},
 		{"512KiB", 512 << 10},
 		{"1GiB", 1 << 30},
 		{"1000", 1000},
 		{" 2MiB ", 2 << 20},
 		{"", def},
 		{"junk", def},
 		{"-1MiB", def},
 		{"0", def},
 		{"12MB", def}, // decimal units are not accepted: say MiB
 	} {
 		if got := ParseSize(c.in, def); got != c.want {
 			t.Errorf("ParseSize(%q) = %d, want %d", c.in, got, c.want)
 		}
 	}
 }
@@ -0,0 +1,254 @@
 package dcache
 import (
 	"io"
 	"log/slog"
 	"strings"
 	"testing"
 	"time"
 )
 func newBatchDB(t *testing.T) *DB {
 	t.Helper()
 	db, err := Open("", 1<<20, slog.New(slog.NewTextHandler(io.Discard, nil)))
 	if err != nil {
 		t.Fatal(err)
 	}
 	t.Cleanup(func() { _ = db.Close() })
 	return db
 }
 func strp(s string) *string { return &s }
 func TestBatchJobRoundTrip(t *testing.T) {
 	db := newBatchDB(t)
 	j := BatchJob{
 		ID: "j1", Caller: "alice", CallerClass: ClassFleet, IDemKey: "k1",
 		Status: "queued", TargetsTotal: 3, CreatedAt: 100, Lease: 100,
 	}
 	if err := db.CreateBatchJob(j); err != nil {
 		t.Fatal(err)
 	}
 	got, ok := db.BatchJob("j1")
 	if !ok {
 		t.Fatal("missing job")
 	}
 	if got.ID != j.ID || got.Caller != "alice" || got.CallerClass != ClassFleet ||
 		got.Status != "queued" || got.TargetsTotal != 3 || got.Lease != 100 || got.CreatedAt != 100 {
 		t.Fatalf("round trip mismatch: %+v", got)
 	}
 	if _, ok := db.BatchJob("nope"); ok {
 		t.Fatal("unknown id must be ok=false")
 	}
 }
 func TestBatchIDemLookup(t *testing.T) {
 	db := newBatchDB(t)
 	if err := db.CreateBatchJob(BatchJob{ID: "j1", Caller: "a", CallerClass: ClassFleet, IDemKey: "k", Status: "running", TargetsTotal: 1, CreatedAt: 100, Lease: 1000}); err != nil {
 		t.Fatal(err)
 	}
 	if id, ok := db.BatchJobByIDem("a", "k", 2000, time.Hour); !ok || id != "j1" {
 		t.Fatalf("live idem: %q %v", id, ok)
 	}
 	if _, ok := db.BatchJobByIDem("a", "k", 5000, time.Hour); ok {
 		t.Fatal("lease-expired job must not match")
 	}
 	if _, ok := db.BatchJobByIDem("b", "k", 2000, time.Hour); ok {
 		t.Fatal("other caller must not match")
 	}
 	// Only a job that is live or has results is reused. A failed (e.g. killed by a restart)
 	// or cancelled job must not be handed back to a resubmit for the rest of its lease.
 	for _, c := range []struct {
 		status string
 		reuse  bool
 	}{{"queued", true}, {"done", true}, {"partial", true}, {"failed", false}, {"cancelled", false}} {
 		key := "k-" + c.status
 		if err := db.CreateBatchJob(BatchJob{ID: "j-" + c.status, Caller: "a", CallerClass: ClassFleet, IDemKey: key, Status: c.status, TargetsTotal: 1, CreatedAt: 100, Lease: 1000}); err != nil {
 			t.Fatal(err)
 		}
 		if _, ok := db.BatchJobByIDem("a", key, 2000, time.Hour); ok != c.reuse {
 			t.Errorf("status %s: reused=%v, want %v", c.status, ok, c.reuse)
 		}
 	}
 }
 func TestBatchLiveCounts(t *testing.T) {
 	db := newBatchDB(t)
 	mk := func(id, caller, status string) {
 		if err := db.CreateBatchJob(BatchJob{ID: id, Caller: caller, CallerClass: ClassFleet, IDemKey: id, Status: status, TargetsTotal: 1, CreatedAt: 1, Lease: 1}); err != nil {
 			t.Fatal(err)
 		}
 	}
 	mk("j1", "a", "queued")
 	mk("j2", "a", "running")
 	mk("j3", "a", "done")
 	mk("j4", "b", "running")
 	if n := db.LiveBatchJobs("a"); n != 2 {
 		t.Fatalf("caller a live=%d want 2", n)
 	}
 	if n := db.LiveBatchJobsTotal(); n != 3 {
 		t.Fatalf("total live=%d want 3", n)
 	}
 }
 func TestBatchTargetsOrderedAndUpdate(t *testing.T) {
 	db := newBatchDB(t)
 	must := func(err error) {
 		t.Helper()
 		if err != nil {
 			t.Fatal(err)
 		}
 	}
 	must(db.CreateBatchJob(BatchJob{ID: "j1", Caller: "a", CallerClass: ClassFleet, IDemKey: "k", Status: "running", TargetsTotal: 3, CreatedAt: 100, Lease: 100}))
 	must(db.PutBatchTargets("j1", []BatchTarget{
 		{JobID: "j1", Idx: 0, URL: "https://a.example/", Options: `{"mode":"clean"}`, Status: "pending"},
 		{JobID: "j1", Idx: 1, URL: "https://b.example/", Status: "pending"},
 		{JobID: "j1", Idx: 2, URL: "https://c.example/", Status: "pending"},
 	}))
 	got, ok := db.BatchTargets("j1")
 	if !ok || len(got) != 3 {
 		t.Fatalf("targets len=%d ok=%v", len(got), ok)
 	}
 	for i := range got {
 		if got[i].Idx != i {
 			t.Fatalf("order broken: got[%d].Idx=%d", i, got[i].Idx)
 		}
 	}
 	// A done write bumps the lease to now and counts the target once.
 	res := strp(`{"content":"ok"}`)
 	must(db.UpdateBatchTarget("j1", 0, 200, "done", res, nil, nil))
 	j, _ := db.BatchJob("j1")
 	if j.Lease != 200 || j.TargetsDone != 1 {
 		t.Fatalf("after first write lease=%d done=%d", j.Lease, j.TargetsDone)
 	}
 	// Re-writing the same target (still a done transition) must not double-count.
 	must(db.UpdateBatchTarget("j1", 0, 201, "done", res, nil, nil))
 	j, _ = db.BatchJob("j1")
 	if j.TargetsDone != 1 {
 		t.Fatalf("double-counted: done=%d", j.TargetsDone)
 	}
 	// A failed write counts too.
 	must(db.UpdateBatchTarget("j1", 1, 202, "failed", nil, strp("upstream 500"), strp("browser")))
 	j, _ = db.BatchJob("j1")
 	if j.TargetsDone != 2 || j.Lease != 202 {
 		t.Fatalf("after failed write lease=%d done=%d", j.Lease, j.TargetsDone)
 	}
 }
 func TestBatchTouchAndStatus(t *testing.T) {
 	db := newBatchDB(t)
 	if err := db.CreateBatchJob(BatchJob{ID: "j1", Caller: "a", CallerClass: ClassFleet, IDemKey: "k", Status: "running", TargetsTotal: 1, CreatedAt: 100, Lease: 100}); err != nil {
 		t.Fatal(err)
 	}
 	if err := db.TouchBatchJob("j1", 500); err != nil {
 		t.Fatal(err)
 	}
 	if j, _ := db.BatchJob("j1"); j.Lease != 500 {
 		t.Fatalf("touch lease=%d want 500", j.Lease)
 	}
 	if err := db.SetBatchJobStatus("j1", "cancelled", "", 600); err != nil {
 		t.Fatal(err)
 	}
 	if j, _ := db.BatchJob("j1"); j.Status != "cancelled" || j.Lease != 600 {
 		t.Fatalf("status=%q lease=%d", j.Status, j.Lease)
 	}
 }
 func TestSweepBatch(t *testing.T) {
 	db := newBatchDB(t)
 	mk := func(id string, lease int64) {
 		if err := db.CreateBatchJob(BatchJob{ID: id, Caller: "a", CallerClass: ClassFleet, IDemKey: id, Status: "done", TargetsTotal: 1, CreatedAt: 1, Lease: lease}); err != nil {
 			t.Fatal(err)
 		}
 		if err := db.PutBatchTargets(id, []BatchTarget{{JobID: id, Idx: 0, URL: "https://x.example/", Status: "done", Result: strp("x")}}); err != nil {
 			t.Fatal(err)
 		}
 	}
 	mk("old", 100)
 	mk("new", 1000)
 	n := db.SweepBatch(300, 100*time.Second) // old: 100+100=200<=300 expired; new: 1100>300 kept
 	if n != 1 {
 		t.Fatalf("swept %d want 1", n)
 	}
 	if _, ok := db.BatchJob("old"); ok {
 		t.Fatal("old job must be gone")
 	}
 	if _, ok := db.BatchJob("new"); !ok {
 		t.Fatal("new job must remain")
 	}
 	if _, ok := db.BatchTargets("old"); ok {
 		t.Fatal("old targets must be gone")
 	}
 }
 func TestEvictBatchOldest(t *testing.T) {
 	db := newBatchDB(t)
 	done := func(id string, lease int64, size int) {
 		if err := db.CreateBatchJob(BatchJob{ID: id, Caller: "a", CallerClass: ClassFleet, IDemKey: id, Status: "done", TargetsTotal: 1, CreatedAt: 1, Lease: lease}); err != nil {
 			t.Fatal(err)
 		}
 		if err := db.PutBatchTargets(id, []BatchTarget{{JobID: id, Idx: 0, URL: "https://x.example/", Status: "pending"}}); err != nil {
 			t.Fatal(err)
 		}
 		if err := db.UpdateBatchTarget(id, 0, lease, "done", strp(strings.Repeat("x", size)), nil, nil); err != nil {
 			t.Fatal(err)
 		}
 	}
 	done("old1", 100, 100)
 	done("old2", 200, 200)
 	done("new", 300, 300)
 	// A running job with one completed target must never be byte-evicted.
 	if err := db.CreateBatchJob(BatchJob{ID: "run", Caller: "a", CallerClass: ClassFleet, IDemKey: "run", Status: "running", TargetsTotal: 2, TargetsDone: 1, CreatedAt: 1, Lease: 400}); err != nil {
 		t.Fatal(err)
 	}
 	if err := db.PutBatchTargets("run", []BatchTarget{
 		{JobID: "run", Idx: 0, URL: "https://x.example/", Status: "pending"},
 		{JobID: "run", Idx: 1, URL: "https://y.example/", Status: "pending"},
 	}); err != nil {
 		t.Fatal(err)
 	}
 	if err := db.UpdateBatchTarget("run", 0, 400, "done", strp(strings.Repeat("x", 500)), nil, nil); err != nil {
 		t.Fatal(err)
 	}
 	// total nbytes = 100+200+300+500 = 1100. Evict oldest done until <= 250:
 	// old1(100), old2(200), new(300) all evicted (oldest first); run stays (live).
 	db.EvictBatchOldest(250)
 	for _, id := range []string{"old1", "old2", "new"} {
 		if _, ok := db.BatchJob(id); ok {
 			t.Fatalf("%s should be byte-evicted", id)
 		}
 	}
 	if _, ok := db.BatchJob("run"); !ok {
 		t.Fatal("running job must not be byte-evicted")
 	}
 	if n := db.BatchNbytes(); n != 500 {
 		t.Fatalf("BatchNbytes=%d want 500", n)
 	}
 }
 func TestMarkInFlightFailed(t *testing.T) {
 	db := newBatchDB(t)
 	mk := func(id, status string) {
 		if err := db.CreateBatchJob(BatchJob{ID: id, Caller: "a", CallerClass: ClassFleet, IDemKey: id, Status: status, TargetsTotal: 1, CreatedAt: 1, Lease: 1}); err != nil {
 			t.Fatal(err)
 		}
 	}
 	mk("q", "queued")
 	mk("r", "running")
 	mk("d", "done")
 	if n := db.MarkInFlightFailed("restart", 999); n != 2 {
 		t.Fatalf("marked %d want 2", n)
 	}
 	if j, _ := db.BatchJob("q"); j.Status != "failed" || j.Error != "restart" || j.Lease != 999 {
 		t.Fatalf("q %+v", j)
 	}
 	if j, _ := db.BatchJob("r"); j.Status != "failed" || j.Error != "restart" {
 		t.Fatalf("r %+v", j)
 	}
 	if j, _ := db.BatchJob("d"); j.Status != "done" {
 		t.Fatalf("done job changed: %+v", j)
 	}
 }
@@ -0,0 +1,53 @@
 package guard
 // P6 task 05: PreCheck is CheckURL without name resolution, for refusing a batch target at
 // submit time.
 import (
 	"context"
 	"net/netip"
 	"strings"
 	"testing"
 )
 func TestPreCheck(t *testing.T) {
 	g := &Guard{
 		AllowPrefixes: []netip.Prefix{netip.MustParsePrefix("127.0.0.0/8")},
 		LookupIP: func(context.Context, string) ([]netip.Addr, error) {
 			t.Fatal("PreCheck resolved a name")
 			return nil, nil
 		},
 	}
 	for _, u := range []string{
 		"https://example.com/",
 		"http://example.com/path?q=1",
 		"https://internal.test/",  // a name: not resolved here, so not refused here
 		"http://127.0.0.1:8080/",  // an allowed literal is exempt from the port rule, as in CheckURL
 		"http://93.184.215.14/",   // a public literal
 		"http://0x7f000001:8080/", // inet_aton form of 127.0.0.1: an allowed literal
 	} {
 		if err := g.PreCheck(u); err != nil {
 			t.Errorf("PreCheck(%q) = %v, want nil", u, err)
 		}
 	}
 	for _, u := range []string{
 		"",
 		"ftp://example.com/",
 		"http://user@example.com/",
 		"http://example.com:8080/",
 		"http://10.0.0.5/",
 		"http://169.254.169.254/latest/meta-data/",
 		"http://[::1]/",
 		"http://0x0a000005/", // inet_aton form of 10.0.0.5
 	} {
 		err := g.PreCheck(u)
 		if err == nil || !strings.HasPrefix(err.Error(), "blocked") {
 			t.Errorf("PreCheck(%q) = %v, want a blocked error", u, err)
 		}
 	}
 	// With no allow list, loopback is refused like any other private literal.
 	var zero Guard
 	if err := zero.PreCheck("http://127.0.0.1/"); err == nil {
 		t.Error("a zero Guard allowed loopback")
 	}
 }
@@ -0,0 +1,61 @@
 package metrics
 import (
 	"io"
 	"net/http/httptest"
 	"strings"
 	"testing"
 	"time"
 )
 type batchSrc struct{}
 func (batchSrc) Snapshot() Snapshot { return Snapshot{} }
 func TestBatchSeries(t *testing.T) {
 	s := New(batchSrc{})
 	s.ObserveBatchJob("created")
 	s.ObserveBatchJob("done")
 	s.ObserveBatchJob("done")
 	s.ObserveBatchJob("reused")
 	s.ObserveBatchJob("some raw string") // folded to "other", never a label
 	s.ObserveBatchTarget("ok")
 	s.ObserveBatchTarget("ok")
 	s.ObserveBatchTarget("blocked")
 	s.ObserveBatchTarget("upstream_5xx")
 	s.ObserveBatchTarget("leak me") // folded to "other"
 	s.SetBatchQueueDepth(3)
 	s.SetBatchTargetsInflight(1)
 	s.ObserveBatchJobSeconds(4 * time.Second)
 	s.ObserveBatchTargetSeconds(1500 * time.Millisecond)
 	s.ObserveBatchResultBytes(4096)
 	req := httptest.NewRequest("GET", "/metrics", nil)
 	req.RemoteAddr, req.Host = "127.0.0.1:9", "127.0.0.1:8890"
 	rec := httptest.NewRecorder()
 	s.Handler().ServeHTTP(rec, req)
 	body, _ := io.ReadAll(rec.Body)
 	out := string(body)
 	for _, want := range []string{
 		`sift_batch_jobs_total{outcome="created"} 1`,
 		`sift_batch_jobs_total{outcome="done"} 2`,
 		`sift_batch_jobs_total{outcome="reused"} 1`,
 		`sift_batch_jobs_total{outcome="other"} 1`,
 		`sift_batch_targets_total{outcome="ok"} 2`,
 		`sift_batch_targets_total{outcome="blocked"} 1`,
 		`sift_batch_targets_total{outcome="upstream_5xx"} 1`,
 		`sift_batch_targets_total{outcome="other"} 1`,
 		`sift_batch_queue_depth 3`,
 		`sift_batch_targets_inflight 1`,
 		`sift_batch_job_seconds_count 1`,
 		`sift_batch_target_seconds_count 1`,
 		`sift_batch_result_bytes_count 1`,
 	} {
 		if !strings.Contains(out, want) {
 			t.Errorf("metrics lack %q", want)
 		}
 	}
 	if strings.Contains(out, "raw") || strings.Contains(out, "leak") {
 		t.Error("a raw outcome string leaked into a label")
 	}
 }