2026-05-14: Upgrade GitHub Actions to Node.js 24 + consolidate agent instructions

Context

GitHub will force all JavaScript actions to run on Node.js 24 by default starting June 2, 2026, and will remove Node.js 20 from runners on September 16, 2026. Three CI jobs (Documentation, Backend, Frontend) emitted deprecation warnings on every run.

Root Cause

Three actions use runs.using: node20 internally:

Action	Old	Runtime	Replacement	Runtime
actions/checkout	@v4	node20	@v5	node24
actions/setup-node	@v4	node20	@v5	node24
codecov/codecov-action	@v4	node20	@v5	composite

Verified by reading each action’s action.yml directly from GitHub.

Additionally, desktop-build.yml was using node-version: 20 for the installed Node version, inconsistent with the rest of the project which uses Node 24.

Agent Instructions Restructure

Discovered two gaps while working on this plan:

1. AGENTS.md was missing Conventions 10 and 11 (they only existed in the instructions file).
2. Both files were injected into AI context, duplicating prose redundantly.

New structure:

• AGENTS.md = complete prose for all 14 conventions (authoritative law)
• agents-plan-checklist.instructions.md = compact actionable checklist (no prose duplication)

New Convention 14 (Semver Release Rule): every completed plan must trigger a semver release via npm run release -- X.Y.Z.

Changes

• .github/workflows/ci.yml — 8 action version bumps
• .github/workflows/desktop-build.yml — 2 action bumps + node-version: 20 → "24"
• AGENTS.md — add C10, C11, C14; fix Summary
• .github/instructions/agents-plan-checklist.instructions.md — compact checklist, add C14

Execution Summary

Commit: d419233

Actual changes

• Updated .github/workflows/ci.yml: all 3 jobs now use actions/checkout@v5, actions/setup-node@v5, and codecov/codecov-action@v5
• Updated .github/workflows/desktop-build.yml: actions/checkout@v5, actions/setup-node@v5 with node-version: "24"
• Rewrote AGENTS.md: added prose for C10, C11, C14; updated Summary to 14 conventions
• Rewrote agents-plan-checklist.instructions.md: stripped prose duplication, compact table, added C14

Deviations from plan

None.

Test results

Gate	Result
Backend unit	⏭ not affected
Backend e2e	⏭ not affected
Frontend unit	⏭ not affected
Frontend e2e	⏭ not affected
CI infra	✅ verified by CI run after push

Key discoveries

• actions/checkout@v4 tag points to a commit labeled “v6 auth style cleanup” — the v4 tag itself still uses node20. Must use @v5 for node24.
• codecov/codecov-action@v5 is a composite action (shell scripts), so node runtime deprecation does not apply to it.
• AGENTS.md had a numbering gap (10, 11 missing) — these were silently living only in the instructions checklist file.