Epic flow: full CI before the epic merges, and sync PRs judged on their deltas #455

Problem

Three small gaps in the epic flow, found by its first two real runs and approved by the owner on 2026-10-13 ("agree with your recommendations, go ahead"):

1. An epic's PR CI runs only the specs the diff selects, so an epic can reach main without a full spec run.
2. A sync PR (main merged into the epic branch) carries main's already-merged files, so merge-check can HOLD or fail owner, harness and contract on content proven on main. Its head cannot be main when there is a conflict to resolve.
3. relay's ci.yml has no workflow_dispatch trigger, so a full run cannot be dispatched on a relay epic head.
4. eve's tests-only guard counts test/e2e/relay-pin.json as a test file, so a re-pin PR fails it without a label that has been forgotten twice.

Root cause

The epic model assumed the PR CI was the full CI and that a sync PR is an ordinary child. Neither holds. Seen on eve#446 and eve#453.

Fix

• merge-check: a full-ci condition for an epic-to-main PR (head epic/<N>-...): a successful workflow_dispatch ci run on the head commit. NA for every other PR.
• merge-check: a sync PR (base epic/<N>-slug, head sync/<N>-...) is judged on the files that differ from main's head, not on its whole file list.
• Flow rules: close-child line 2 adds the dispatched full run; line 4 names the sync/<N>-main branch and says conflicts are resolved on it.
• relay ci.yml: add workflow_dispatch.
• eve scripts/ci-guards.sh: count exactly test/e2e/relay-pin.json as code for the tests-only guard (eve PR fix: relay-pin.json is a pin, not a test, for the tests-only guard (#455) #469). relay's copy of the script is not changed: it has no such file; the header's "same file in every repo" now differs by one line, accepted and logged.

Contract

Ownership: the owner's merge-check (merge-check, CONTRACT.md, test_merge_check.py), the owner's flow rules file and the remote-coord/fanout wording, and relay's .github/workflows/ci.yml (own child PR). Not in a repo except the last. Gate change (#2), approved by the owner in this conversation.
Proof: the merge-check suite (existing 101 stay green, new tests from the criteria, one break-and-restore each), then one rehearsal epic across both repos on the real tools, reverted afterwards.

Ownership for the guard carve-out PR (eve#469), recorded 2026-10-14: scripts/ci-guards.sh, test/static/ci-guards-selftest.js. Two files, about 150 lines.