[gregoryfoster]

Refs #57 (the Watcher notice below is still to post, with approval).

Plan: docs/plans/2026-10-21-57-dispatch-essence-notice.md.

What changes

• The contract loses resolve_dispatch_essence at all four rule sites: AGENTS.md (the contract list only), docs/DEPLOYMENT.md "Bumping co-core" step 4, spec D5, and spec §5's bump list. The contract is now the content.process / content.derived models and canonical_text semantics.
• §5 says why, once. The issuer resolves on its own pin, and Processor never re-resolves. So a change is notice, carrying the either-order reasoning and the moved digests. It becomes coordination again only if Processor starts resolving essences itself.
• Spec amendment 2026-10-21. Take co-core's XML and feed extractors in step with Watcher, and re-run parity with a feed fixture #29's coordination on watcher#366 was more than the rule needed; JSON: take co-core's JsonExtractor (cannobserv#354) and add a jsonpath parity fixture #37's notice was what it needed. The 2026-10-12 and 2026-10-20 entries, and §5's per-bump notes, are unchanged.
• Unchanged: notice on every processor_version move; EXTRACTOR_BY_ESSENCE.

The guard test (tests/test_pin.py)

test_processor_never_resolves_a_dispatch_essence walks every src/processor/**/*.py AST. It fails on an import of, or a Name / Attribute use of, resolve_dispatch_essence or extension_media_type, and its message points back to §5. It checks code, not text, so a docstring may quote them. test_the_guard_catches_code_not_text holds the walker to that: it catches four code forms and passes a docstring, a comment and extractor_for_essence.

Red, on a scratch copy of src/ + tests/ with from co_core.pure.extract import resolve_dispatch_essence planted in processors/extract.py:

E       AssertionError: Processor resolves a dispatch essence itself: {'src/processor/processors/extract.py': ['line 16: resolve_dispatch_essence']}. A change to essence resolution is then a contract change, coordinated with Watcher, not notice: restore it to the contract (spec §5, D5; AGENTS.md; DEPLOYMENT.md step 4; processor#57).
FAILED tests/test_pin.py::test_processor_never_resolves_a_dispatch_essence - ...
1 failed, 18 deselected in 0.50s

Green here: tests/test_pin.py 19 passed; the full suite 696 passed, 14 skipped (environmental: no .env in the worktree, /etc/processor unreadable as exedev); ruff clean.

Premise checked on co-core 0.38.0: extractor_for_essence and extraction_overrides_for_essence, which Processor does call, don't call either resolver.

Known limit: a string-keyed lookup (getattr(m, "resolve_dispatch_essence")) isn't caught. That would be deliberate evasion, not drift.

No deploy: nothing under src/, deploy/, scripts/deploy.sh, pyproject.toml or uv.lock changes.

Draft: the Watcher notice (CannObserv/watcher#368, after the merge, needs approval)

Notice from Processor: #57 narrows D5's coordination rule. No action is needed from Watcher.

• A change to essence resolution is now notice, not coordination. resolve_dispatch_essence and extension_media_type leave D5's contract, which is now the content.process / content.derived models and canonical_text semantics. Watcher resolves the essence on its own pin. Processor dispatches whatever essence arrives and never re-resolves it. So either adoption order is safe:
  • an old Watcher keeps sending the essence it sent, which reaches the same extractor as before;
  • a new Watcher's essence reaches the old extractor on an old Processor, and the new one on a new Processor.
• Every bump still gives notice here, with the new processor_version and the moved digests. A dispatch change for an essence Watcher sends today shows up in those digests.
• A test keeps the premise true. tests/test_pin.py fails if anything under src/processor/ imports or uses either function. If Processor ever resolves essences itself, the test fails, and the coordination rule comes back with it.
• This is what JSON: take co-core's JsonExtractor (cannobserv#354) and add a jsonpath parity fixture #37's notice above already did. Take co-core's XML and feed extractors in step with Watcher, and re-run parity with a feed fixture #29's coordination on #366 was more than the rule needed. Spec: D5 and §5, amended 2026-10-21 ().

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