Keep gdlc's config schema-valid and in sync automatically

The configure-gdlc agent is a one-time authoring flow. This page covers the two automated checks that keep an already-written .config/gdlc/config.yml from silently drifting afterward (ADR-0009, Story #264) — a CI gate over PR diffs, and a passive session-start hook.

CI gate: schema validation on every PR

.github/workflows/ci.yml’s gdlc-config-validate job runs the same validator write_gdlc_config uses (GDLC_CONFIG_SECTION_SCHEMAS), via the already-built plugins/github-sdlc-planning/mcp-server/dist/validate-gdlc-config.js, against every .config/gdlc/config.yml found in the repo tree. It fails the PR if any file doesn’t validate — including a hand-edited file that never went through the agent at all.

This is the gate that would have caught issue #247/#248 (a prLifecycle field the loader supported but the schema file didn’t declare) before merge, not just after a bug report.

Adopting this in a different repo: copy the job, point validator at wherever your own build of github-sdlc-planning’s MCP server dist lives (or vendor the single bundled file — it has no runtime dependencies once built), and adjust the find scope if your config lives somewhere other than .config/gdlc/config.yml.

Session-start hook: passive drift detection

hooks/config-drift-check.mjs runs on every SessionStart alongside the existing session-start.mjs (hooks/hooks.json). Two checks, both non-blocking (silent when nothing is wrong, matching every other advisory hook in this plugin):

1. Schema validity — re-validates the resolved config the same way the CI gate does. Catches a file that was valid when written but no longer matches the schema after it evolved.
2. Board reachability — a best-effort, 5-second-timeout gh project view check against the configured board.projectOwnerLogin/ projectNumber. Only reports drift on a confirmed “not found”; an auth hiccup, network blip, or missing gh login is treated as inconclusive, never misreported as “the board was deleted.”

Unlike the ticket-hygiene hook trio (register-hygiene-hook-at-project-level.md), this hook is not copyable to a project that doesn’t install github-sdlc-planning — it imports the plugin’s own built MCP-server dist (../mcp-server/dist/validate-gdlc-config.js) by relative path, so it only runs correctly from inside this plugin’s own hooks/ directory. If you want equivalent drift detection in a repo that doesn’t install this plugin, invoke the CI gate’s validate-gdlc-config.js script directly instead (see above), or run configure-gdlc periodically by hand.

Verify it’s working

Write a schema-invalid .config/gdlc/config.yml (e.g. board.projectNumber as a non-numeric string) and start a new session in that directory — hookSpecificOutput.additionalContext should name the file and point at the configure-gdlc skill. A schema-valid file with no board section, or none at all, produces no output — the correct, non-noisy result.