add validate.sh pipeline gate and audit convention notes

.agents/validate.sh is the commit gate: full E2E suite, container
security-header check, and repo-hygiene checks must all pass before a
phase is committed. AGENTS.md now documents the audit-driven
conventions (M-1 innerHTML/terminal input, M-2 simulated curl/wget,
M-4 security-header snippet, L-2 server_tokens) and the test-locked
featured-projects grid.

LLM-Generated: true

AGENTS.md

@@ -17,8 +17,14 @@ Rules for any agent working in this repository.
      deployed artifact — never test `src/` directly).
    - `npm test` — the Playwright E2E suite (pinned `@playwright/test`
      1.63.0; do not bump without re-checking the cached browser revision).
-   - For any nginx/Dockerfile change: `./scripts/check-headers.sh`
-     (Phase 03+).
+   - `.agents/validate.sh` — the pipeline gate: full E2E suite + the container
+     security-header check + repo-hygiene checks; must exit 0 before a phase is
+     committed.
+   - For any `nginx.conf` / `nginx-security-headers.inc` / Dockerfile change:
+     `./scripts/check-headers.sh` (added by Phase 03, run automatically by
+     `.agents/validate.sh` when a container runtime exists). It builds the real
+     image, serves it on `127.0.0.1:18099` and must print
+     `HEADER CHECK PASSED`; don't substitute a hand-rolled `curl` for it.
 
 ## Never
 - Modify `.agents/PLAN.md` except via an explicit user-approved change to the
@@ -37,6 +43,36 @@ Rules for any agent working in this repository.
 - Static site: edits in `src/` → `./build.sh` → `dist/` (hash-cached names).
   New root-level assets are picked up automatically by `build.sh`; nested
   directories are **not** (keep JS files flat in `src/`).
+- Terminal input is untrusted: never render typed input or `commandHistory`
+  with `innerHTML` — route it through `updateDisplay()`/`textContent`
+  (audit M-1, guarded by the markup-payload test in
+  `tests/e2e/02-terminal.spec.js`). The only `innerHTML` uses allowed in
+  `src/terminal.js` are static prompt literals, the `clear`/prank element
+  wipes, and the canned `neofetch` output (the `cmdText === 'neofetch'` branch —
+  every other command output goes through `textContent`). In
+  `terminal-vim.js`/`terminal-achievements.js` `innerHTML` is acceptable only
+  with static markup or `escapeHtml()`-escaped text.
+- The fake terminal does zero network I/O: `curl`/`wget` render canned output
+  from `simulatedCurlOutput()` / `simulatedWgetOutput()` in
+  `src/terminal-commands.js` (pure string builders, no DOM, no network). Keep
+  any browser-side fetch call out of `src/` entirely (audit M-2, Phase 02).
+  Guarded by the curl/wget regression test in `tests/e2e/02-terminal.spec.js`,
+  which records every request whose URL falls outside `baseURL` from
+  `playwright.config.js` and fails the suite if the list is not empty.
+- Security headers live in `nginx-security-headers.inc` (the Dockerfile copies
+  it to `/etc/nginx/snippets/security-headers.inc`) and **every** `location` in
+  `nginx.conf` `include`s it. nginx does not merge `add_header` across
+  configuration levels, so never rely on server-level inheritance and never add
+  inline security `add_header` lines to `nginx.conf` — put them in the snippet
+  (audit M-4, Phase 03). `server_tokens off;` stays in the `server` block
+  (audit L-2). `scripts/check-headers.sh` guards this rule: drop one `include`
+  from a location and the check fails for that path.
+- Featured-projects content is test-locked: the `#projects` grid in
+  `src/index.html` (six cards in a fixed order — Brain of Reese first with its
+  Gitea source link, ServWaf last with no link because it is closed source) is
+  asserted by the `featured projects show the six updated cards in order` test
+  in `tests/e2e/01-page.spec.js`. Edit the cards in `src/index.html` and update
+  that test in the same change (Phase 05).
 - Terminal modules: `terminal-commands.js` (canned data),
   `terminal-achievements.js`, `terminal-vim.js`, `terminal.js` (core) — load
   order is fixed in `index.html` (all `defer`); keep dependencies pointing