chore(ci): consolidate the workflow directory

[thecodedrift]

Eight workflow files become six. Two OpenSpec checks are deleted outright, the changeset gate stops failing, and ci.yml gets a name that matches the check it publishes.

ci.yml → validate.yml. File and workflow name only. The job is still Validate, which is the required status check on main, so branch protection needs no change.

Both OpenSpec checks are replaced by one step on main. pr-check-openspec.yml and openspec-rot.yml are gone. Neither could ask its question cleanly: an unarchived change directory is the normal state of a pull request, since a change is archived exactly once on the last slice of the work — so the PR gate had to infer stack position to avoid firing on work still in flight, and the nightly sweep had to date directories from git history to guess whether a stack was abandoned. Both guessed, and a check that is expected-red across most of a stack is one people learn to route around.

validate.yml now carries a step, gated on push events to main, that fails while main holds anything under openspec/changes/ other than archive/. On main the question has an unambiguous answer: once the work has landed, what is left is debris.

The tradeoff worth reviewing: a stack that merges forward lands its change directory on main and archives it only on the final slice, so main runs red for as long as that stack is draining. That red blocks nothing — branch protection reads each PR's own Validate run, not main's — and the alternative is the staleness heuristic this replaces. A stack that merges down keeps main clean throughout. If you would rather main never sit red, that is the knob to turn, and it belongs in this PR rather than after it.

require-changeset.yml → changeset.yml, advisory. It emits a warning and a step summary instead of failing, and it looks for a changeset added or modified anywhere between main and the PR head rather than in the PR's own diff. That range covers every branch below in a stack, so one changeset on the bottom branch satisfies every PR above it and the stack question answers itself — no base-ref guard, no branches: filter. skip-changeset survives only to silence the warning, which is what it had degenerated into: a way to clear a red check rather than a record that a change ships no release note.

claude-code-review-on-demand.yml and vale-binaries.yml are untouched.

Docs move with the code — the CLAUDE.md stacking section, the iterate-pr skill's two structural-failure sections, and openspec/specs/infrastructure/spec.md, which gains requirements for the main-only archive check and for the changeset check being advisory. The branches: filter lesson is kept and re-anchored; it was true independently of the guard it was documenting.

This change ships no release note, so it adds no changeset. Under the new workflow that produces a warning rather than a failure, which is the first thing it demonstrates.

[Copilot]

Pull request overview

Consolidates and simplifies GitHub Actions workflows by renaming the primary CI workflow to match the required check name, removing PR-time OpenSpec archive gating in favor of a main-only cleanliness check, and converting the changeset requirement into a stack-aware advisory warning. Documentation is updated to reflect the new workflow model and stacked-PR guidance.

Changes:

• Rename ci.yml → validate.yml (workflow file/name alignment) and add a push-to-main-only step that fails if openspec/changes/ contains unarchived directories.
• Replace the failing require-changeset gate with a new changeset.yml workflow that warns (and is stack-aware by diffing against main).
• Remove the previous OpenSpec PR archive check and the nightly rot sweep; update docs/specs/skill guidance accordingly.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
openspec/specs/infrastructure/spec.md	Updates CI/changeset requirements and documents the new main-only OpenSpec archive check behavior.
CLAUDE.md	Refreshes stacked-PR guidance to match the new archive + advisory changeset behavior.
.github/workflows/validate.yml	New primary Validate workflow; adds main-only unarchived OpenSpec change detection step.
.github/workflows/changeset.yml	New advisory, stack-aware changeset warning workflow.
.github/workflows/ci.yml	Removed in favor of validate.yml.
.github/workflows/require-changeset.yml	Removed in favor of advisory changeset.yml.
.github/workflows/pr-check-openspec.yml	Removed (PR-time OpenSpec archive gate eliminated).
.github/workflows/openspec-rot.yml	Removed (nightly rot sweep eliminated).
.agents/skills/iterate-pr/SKILL.md	Updates iterate-pr operational guidance to reflect the new CI checks model.

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