diff --git a/.agents/validate.sh b/.agents/validate.sh
new file mode 100755
index 0000000..dfd38c6
--- /dev/null
+++ b/.agents/validate.sh
@@ -0,0 +1,90 @@
+#!/usr/bin/env bash
+# .agents/validate.sh — validation gate for the phased-execution pipeline.
+#
+# A unit is only moved to .agents/phases/complete/ if this script exits 0,
+# and a phase is only COMMITTED if its final pass exits 0 — so this script
+# is the last line of defense for "no phase commits unless 100% passing".
+# It MUST run the project's FULL test suite (every test, not a subset) plus
+# its linter, so a failure anywhere in the project blocks the commit.
+#
+# Adapt the checks below to this project's real test suite, linter, and
+# coverage floor, then commit the result.
+set -uo pipefail
+rc=0
+
+if [[ -f pyproject.toml || -f pytest.ini || -f setup.py ]]; then
+  python3 -m pytest -q || rc=1
+  if command -v ruff >/dev/null 2>&1; then
+    ruff check . || rc=1
+  fi
+fi
+
+if [[ -f package.json ]]; then
+  npm test --silent || rc=1
+fi
+
+# --- project-specific gate: container security headers (Phase 03, audit M-4) --
+# Builds the real nginx image and asserts all four hardening headers on every
+# response class (/, /index.html, a hashed asset). Needs a container runtime;
+# if the host has none the check is skipped loudly instead of failing silently.
+if [[ -x scripts/check-headers.sh ]]; then
+  if command -v podman >/dev/null 2>&1; then RT=podman
+  elif command -v docker >/dev/null 2>&1; then RT=docker
+  else RT=""
+  fi
+  if [[ -n "$RT" ]]; then
+    ./scripts/check-headers.sh || rc=1
+    # check-headers.sh removes its container but not its scratch image tag;
+    # drop it here so repeated gates do not fill container storage.
+    leftovers="$("$RT" images --format '{{.Repository}}:{{.Tag}}' 2>/dev/null | grep 'homepage-headercheck-' || true)"
+    if [[ -n "$leftovers" ]]; then
+      printf '%s\n' "$leftovers" | xargs -r "$RT" rmi -f >/dev/null 2>&1 || true
+    fi
+  else
+    echo "WARN: no podman/docker available — SKIPPING scripts/check-headers.sh (security-header gate not exercised)" >&2
+  fi
+fi
+
+# --- repo hygiene (language-agnostic; runs in every project) ------------------
+# Scoped staging commits everything the phase touched, so a file that is not
+# ignored gets committed — including raw log drops and key material. These
+# gates make the phase fail instead. Fix by untracking, keeping the working
+# copy:  git rm --cached <file>
+if git rev-parse --is-inside-work-tree >/dev/null 2>&1; then
+  # 1. A tracked file that matches a .gitignore rule should never be tracked.
+  junk="$(git ls-files -i -c --exclude-standard 2>/dev/null || true)"
+  if [[ -n "$junk" ]]; then
+    echo "repo hygiene: TRACKED files match .gitignore rules (untrack with 'git rm --cached <file>'):" >&2
+    printf '  %s\n' "$junk" >&2
+    rc=1
+  fi
+
+  # 2. Personal-data / key-material file SHAPES that must never be tracked,
+  #    even in a project with no .gitignore rule for them.
+  DANGEROUS='(^|/)[^/]*\.log$|(^|/)[^/]*\.jsonl$|(^|/)\.env($|\.)|\.(pem|key|crt|cer|p12|pfx|keystore|jks)$|(^|/)(id_rsa|id_ecdsa|id_ed25519)(\.pub)?$|(^|/)(credentials|service-account|client_secret)([-a-z0-9]*)\.json$'
+  bad="$(git ls-files | grep -E "$DANGEROUS" || true)"
+  if [[ -n "$bad" ]]; then
+    echo "repo hygiene: TRACKED files look like log drops / key material (untrack with 'git rm --cached <file>' and add a .gitignore rule):" >&2
+    printf '  %s\n' "$bad" >&2
+    rc=1
+  fi
+
+  # 3. Project-specific content scan for personal data inside tracked files
+  #    (client IPs, account ids, ...). Empty by default — fill it in per
+  #    project, and allow-list documentation ranges (RFC 5737 / 4193 / 3849,
+  #    127.0.0.0/8, RFC1918) so fixtures do not trip it. Format: one ERE.
+  PII_PATTERNS="${PII_PATTERNS:-}"
+  if [[ -n "$PII_PATTERNS" ]]; then
+    hits="$(git ls-files -z | xargs -0 grep -IHnE "$PII_PATTERNS" 2>/dev/null || true)"
+    if [[ -n "$hits" ]]; then
+      echo "personal-data gate: TRACKED files match PII_PATTERNS — redact them:" >&2
+      printf '  %s\n' "$hits" >&2
+      rc=1
+    fi
+  fi
+fi
+
+if [[ $rc -ne 0 ]]; then
+  echo "validation FAILED (see output above)"
+fi
+exit "$rc"
diff --git a/AGENTS.md b/AGENTS.md
index 2271d4d..59f5c3c 100644
--- a/AGENTS.md
+++ b/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