P6 during the run: split the runner task (02 core, 03 workers); guard.PreCheck as an owner commit; AGENTS.md: write code into files early

Task 02 (the whole runner) ended at 21:08 with no file and no commit: Ornith wrote the
implementation out in its reply (~700 lines), OpenCode compacted the session, and the model
then emitted a malformed tool call. It had also looked for the given test at a wrong path
("_files/…" relative to the plan: my ambiguity).

- 02-runner → 02-runner-core (types, Submit, Status, Touch, Cancel; no goroutines) and
  03-runner-workers; the given test split to match (runner_core_test.go gains three tests:
  queued storage, cancel while queued, Status never moves the lease); later tasks renumbered
  04-09 and every cross-reference checked.
- Copy paths spelled from the repo root.
- guard.PreCheck (+ its test) is committed here by the owner: the old task 05 told the
  implementer to edit internal/guard/, which AGENTS.md forbids. My contradiction.
- AGENTS.md rule 6: write code into files early, in small steps.
Both runner test files compile against a panic-only skeleton (the core file also alone) and
fail there on panic: todo.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/plans/p6/README.md

@@ -39,13 +39,17 @@ Decisions (settled with the owner, 2026-09-26; revised after review the same eve
 | 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` |
+| 02-runner-core | `internal/batch` (types, Submit, Status, Touch, Cancel; no workers) | `batch/runner_core_test.go` |
+| 03-runner-workers | `internal/batch` (workers, retry, cancel in flight, hooks) | `batch/runner_test.go` |
+| 04-metrics | `internal/metrics` | `metrics/batch_test.go` |
+| 05-fetchtarget | `internal/api` (the one refactor of working code) | `api/fetchtarget_test.go` |
+| 06-batch-wiring | `internal/api` | `api/batchrun_test.go` |
+| 07-api-endpoints | `internal/api` | `api/batch_test.go` |
+| 08-serve-config | `internal/config`, `cmd/sift/serve.go` | `config/batch_test.go` |
+| 09-cli-docs | `cmd/sift`, README, skill | `cmd_sift/batch_test.go` |
+
+`guard.PreCheck` and its test are on master (owner commit): `AGENTS.md` forbids the implementer
+to edit `internal/guard/`, the security boundary.
 
 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
@@ -56,3 +60,22 @@ work) on top of the P5 pool (`internal/pdfpool`), cache (`internal/dcache`), and
 (`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.
+
+## Changes during the run
+
+- **Task 02 (runner), first attempt, 20:39–21:08. Model and task size, in about equal parts.**
+  - The session wrote the whole runner out as ~700 lines of reasoning in its reply, never in a
+    file. OpenCode compacted the context, and the model then emitted a malformed tool call
+    (`</tool_call>`) and ended with no commit and no file.
+  - It had also looked for the given test at a wrong path. The task said `_files/…` relative
+    to the plan; that is my ambiguity.
+  - The owner changes:
+    - task 02 split into **02-runner-core** (no goroutines) and **03-runner-workers**, with the
+      given test split to match (`runner_core_test.go` + `runner_test.go`); later tasks
+      renumbered 04–09;
+    - every copy path is spelled from the repo root (`docs/plans/p6/_files/…`);
+    - `AGENTS.md` rule 6: write code into files early, in small steps;
+    - `guard.PreCheck` moved to an owner commit on master. The old task 05 (now 06) told the
+      implementer to edit `internal/guard/`, which `AGENTS.md` forbids: my contradiction, found
+      while fixing the above.
+