diff --git a/docs/preflight.md b/docs/preflight.md
new file mode 100644
index 0000000..ee012f5
--- /dev/null
+++ b/docs/preflight.md
@@ -0,0 +1,83 @@
+# Pre-flight gate for `gx branch finish`
+
+`gx branch finish` runs a **pre-flight verification script** in the
+agent's worktree **before** any push happens. If the script fails, the
+push is refused and the PR is never created — the broken commit never
+reaches CI, the merge funnel, or the review surface.
+
+This is the cheapest gate in the agent workflow:
+
+| Gate | Cost | Catches |
+| --- | --- | --- |
+| Local pre-flight (this) | free, runs on agent's CPU | most regressions before they reach CI |
+| Draft PR (gx finish opens it) | $0 — draft skips CI | nothing extra; the gate is the next step |
+| `ready_for_review` flip (auto-promote) | first CI run | regressions pre-flight missed |
+| Branch protection on `main` | required CI must be green | merge-time defense in depth |
+
+Pre-flight is enabled by default. Disable per-call with `--no-preflight`,
+or globally with `GUARDEX_FINISH_PREFLIGHT=0`.
+
+## Convention
+
+`gx branch finish` looks for `scripts/agent-preflight.sh` inside the
+target repo's working tree. If it is executable, it runs from the repo
+root. Non-zero exit refuses the push.
+
+For gitguardex-managed projects, `gx setup` scaffolds a default
+`scripts/agent-preflight.sh` that auto-detects the project stack and
+runs conventional verification:
+
+- **Node + pnpm** (lockfile present): `pnpm typecheck && pnpm lint && pnpm test`, each only if the package.json script exists.
+- **Node + npm** (lockfile present): `npm test` if defined.
+- **Rust** (`Cargo.toml`): `cargo check --quiet`.
+- **Python** (`pyproject.toml`): `ruff check .` if `ruff` is installed.
+
+If none of these match, pre-flight passes with a warn-only message —
+the script doesn't refuse pushes for repos it can't classify.
+
+## Override per-project
+
+Replace the symlinked default with a custom script:
+
+```bash
+rm scripts/agent-preflight.sh                # remove the symlink
+# write your own script that exits non-zero on failure
+chmod +x scripts/agent-preflight.sh
+```
+
+The custom script receives no arguments and runs with the worktree as
+its working directory. It MUST return non-zero to block a push.
+
+## Auto-promote on pass
+
+After pre-flight passes, `gx branch finish` creates the PR. If the PR
+is in draft state (manually opened earlier, or via a future `--draft`
+option here), the finish script automatically marks it
+ready-for-review by calling `gh pr ready`. With the budget-friendly
+CI defaults (draft PRs skip CI), this is the moment CI is allowed to
+fire — once, on a known-passing commit.
+
+Disable per-call with `--no-auto-promote`, or globally with
+`GUARDEX_FINISH_AUTO_PROMOTE=0`.
+
+## Flags + env vars
+
+| CLI flag | Env var | Default | Effect |
+| --- | --- | --- | --- |
+| `--preflight` / `--no-preflight` | `GUARDEX_FINISH_PREFLIGHT` | `true` | Run/skip the pre-flight gate. |
+| `--preflight-script <path>` | `GUARDEX_FINISH_PREFLIGHT_SCRIPT` | `scripts/agent-preflight.sh` | Override the script path (relative to worktree, or absolute). |
+| `--auto-promote` / `--no-auto-promote` | `GUARDEX_FINISH_AUTO_PROMOTE` | `true` | Promote a draft PR to ready-for-review after pre-flight passes. |
+
+## When to bypass
+
+Only `--no-preflight` if:
+
+- the pre-flight script itself is broken and you need to ship the fix,
+- you are landing an emergency rollback and CI/branch protection will
+  catch any remaining issue, or
+- your repo has no `scripts/agent-preflight.sh` and you've decided not
+  to write one.
+
+For ordinary "the tests are slow" cases, write a faster pre-flight
+that only runs the targeted suite for changed paths, instead of
+disabling the gate entirely.
diff --git a/openspec/changes/agent-claude-gx-finish-preflight-and-auto-promote-2026-05-14-01-09/.openspec.yaml b/openspec/changes/agent-claude-gx-finish-preflight-and-auto-promote-2026-05-14-01-09/.openspec.yaml
new file mode 100644
index 0000000..93831bd
--- /dev/null
+++ b/openspec/changes/agent-claude-gx-finish-preflight-and-auto-promote-2026-05-14-01-09/.openspec.yaml
@@ -0,0 +1,2 @@
+schema: spec-driven
+created: 2026-05-13
diff --git a/openspec/changes/agent-claude-gx-finish-preflight-and-auto-promote-2026-05-14-01-09/notes.md b/openspec/changes/agent-claude-gx-finish-preflight-and-auto-promote-2026-05-14-01-09/notes.md
new file mode 100644
index 0000000..3970b8c
--- /dev/null
+++ b/openspec/changes/agent-claude-gx-finish-preflight-and-auto-promote-2026-05-14-01-09/notes.md
@@ -0,0 +1,26 @@
+# agent-claude-gx-finish-preflight-and-auto-promote-2026-05-14-01-09 (T1)
+
+Branch: `agent/claude/gx-finish-preflight-and-auto-promote-2026-05-14-01-09`
+
+Shifts agent verification from billable cloud Actions minutes to free local CPU. `gx branch finish` now runs a `scripts/agent-preflight.sh` gate in the worktree BEFORE pushing; non-zero refuses the push. On pass, any draft PR is promoted to ready-for-review so the budget-friendly CI defaults can fire once on a known-passing commit.
+
+## Files
+
+- `templates/scripts/agent-preflight.sh` (new) — auto-detects Node/pnpm, Node/npm, Rust, Python and runs conventional verification.
+- `scripts/agent-preflight.sh` (new symlink) — points at the template per the existing paired-script convention.
+- `templates/scripts/agent-branch-finish.sh` — adds `--no-preflight` / `--preflight` / `--preflight-script <path>` / `--no-auto-promote` / `--auto-promote` flags + matching `GUARDEX_FINISH_PREFLIGHT*` / `GUARDEX_FINISH_AUTO_PROMOTE` env vars; calls `run_preflight` before any push; calls `maybe_auto_promote_pr` after the PR exists.
+- `scripts/check-script-symlinks.sh` — adds `scripts/agent-preflight.sh` to the required-symlinks list.
+- `src/context.js` — adds `scripts/agent-preflight.sh` to `TEMPLATE_FILES` so `gx setup` scaffolds it into downstream projects.
+- `docs/preflight.md` (new) — documents the convention.
+
+## Acceptance
+
+- Pre-flight runs before push; non-zero refuses push (verified via shell syntax + `--no-preflight` override path exists).
+- Symlink check passes (`scripts/check-script-symlinks.sh` now expects 11 paired files).
+- gitguardex own `npm test` green after symlink + finish-script edits.
+
+## Cleanup
+
+- [ ] Run: `gx branch finish --branch agent/claude/gx-finish-preflight-and-auto-promote-2026-05-14-01-09 --base main --via-pr --wait-for-merge --cleanup`
+- [ ] Record PR URL + `MERGED` state.
+- [ ] Confirm sandbox worktree is gone.
diff --git a/scripts/agent-preflight.sh b/scripts/agent-preflight.sh
new file mode 120000
index 0000000..b611e44
--- /dev/null
+++ b/scripts/agent-preflight.sh
@@ -0,0 +1 @@
+../templates/scripts/agent-preflight.sh
\ No newline at end of file
diff --git a/scripts/check-script-symlinks.sh b/scripts/check-script-symlinks.sh
index a2e9fc2..33a736f 100755
--- a/scripts/check-script-symlinks.sh
+++ b/scripts/check-script-symlinks.sh
@@ -18,6 +18,7 @@ required_symlinks=(
   scripts/agent-branch-finish.sh
   scripts/agent-branch-merge.sh
   scripts/agent-file-locks.py
+  scripts/agent-preflight.sh
   scripts/agent-worktree-prune.sh
   scripts/codex-agent.sh
   scripts/install-agent-git-hooks.sh
diff --git a/src/context.js b/src/context.js
index b9d0d38..6a83402 100644
--- a/src/context.js
+++ b/src/context.js
@@ -166,6 +166,7 @@ function toDestinationPath(relativeTemplatePath) {
 // safety block (auto-managed by syncManagedGitignoreLines below).
 const TEMPLATE_FILES = [
   'scripts/agent-session-state.js',
+  'scripts/agent-preflight.sh',
   'scripts/guardex-docker-loader.sh',
   'scripts/guardex-env.sh',
   'scripts/install-vscode-active-agents-extension.js',
diff --git a/templates/scripts/agent-branch-finish.sh b/templates/scripts/agent-branch-finish.sh
index 0af6475..8f5325f 100755
--- a/templates/scripts/agent-branch-finish.sh
+++ b/templates/scripts/agent-branch-finish.sh
@@ -19,6 +19,9 @@ PARENT_GITLINK_AUTO_COMMIT_RAW="${GUARDEX_FINISH_PARENT_GITLINK_AUTO_COMMIT:-tru
 AUTO_RESOLVE_MODE_RAW="${GUARDEX_FINISH_AUTO_RESOLVE:-none}"
 AUTO_RESOLVE_SAFE_GLOBS_DEFAULT='.omc/**:.omx/state/**:.dev-ports.json:apps/logs/**:.agents/settings.local.json:.codex/state/**:.claude/state/**'
 AUTO_RESOLVE_SAFE_GLOBS_RAW="${GUARDEX_FINISH_AUTO_RESOLVE_SAFE_GLOBS-$AUTO_RESOLVE_SAFE_GLOBS_DEFAULT}"
+PREFLIGHT_ENABLED_RAW="${GUARDEX_FINISH_PREFLIGHT:-true}"
+PREFLIGHT_SCRIPT_RAW="${GUARDEX_FINISH_PREFLIGHT_SCRIPT:-scripts/agent-preflight.sh}"
+AUTO_PROMOTE_DRAFT_RAW="${GUARDEX_FINISH_AUTO_PROMOTE:-true}"
 
 run_guardex_cli() {
   if [[ -n "$CLI_ENTRY" ]]; then
@@ -67,11 +70,83 @@ normalize_int() {
   printf '%s' "$value"
 }
 
+# Resolve the pre-flight script path against the source worktree. The
+# caller passes either the configured path (which may be relative) or
+# an empty string; we return the absolute path if it exists and is
+# executable, otherwise return empty.
+resolve_preflight_script() {
+  local worktree="$1"
+  local configured="$2"
+  if [[ -z "$configured" ]]; then
+    configured="scripts/agent-preflight.sh"
+  fi
+  if [[ "$configured" = /* ]]; then
+    if [[ -x "$configured" ]]; then
+      printf '%s' "$configured"
+    fi
+    return 0
+  fi
+  local candidate="${worktree}/${configured}"
+  if [[ -x "$candidate" ]]; then
+    printf '%s' "$candidate"
+  fi
+}
+
+# Run the pre-flight verification gate in the agent worktree before
+# any push happens. Returns 0 on success or when no gate is
+# configured; returns non-zero (and prints a hint) on failure, which
+# the caller propagates so the push is refused.
+run_preflight() {
+  local worktree="$1"
+  if [[ "$PREFLIGHT_ENABLED" -ne 1 ]]; then
+    return 0
+  fi
+  local script_path
+  script_path="$(resolve_preflight_script "$worktree" "$PREFLIGHT_SCRIPT_RAW")"
+  if [[ -z "$script_path" ]]; then
+    echo "[agent-branch-finish] No executable pre-flight script at ${PREFLIGHT_SCRIPT_RAW} (in ${worktree}); skipping pre-flight." >&2
+    return 0
+  fi
+  echo "[agent-branch-finish] Running pre-flight: ${script_path}" >&2
+  if ( cd "$worktree" && "$script_path" ); then
+    echo "[agent-branch-finish] Pre-flight passed." >&2
+    return 0
+  fi
+  echo "[agent-branch-finish] Pre-flight FAILED; refusing push. Override with --no-preflight if you really mean it." >&2
+  return 1
+}
+
+# After a PR exists, if it is in draft and auto-promote is enabled,
+# mark it ready-for-review. With the budget-friendly CI defaults
+# (draft PRs skip CI), this is the moment when CI is allowed to fire.
+maybe_auto_promote_pr() {
+  local pr_url="$1"
+  if [[ -z "$pr_url" ]] || [[ "$AUTO_PROMOTE_DRAFT" -ne 1 ]]; then
+    return 0
+  fi
+  if ! command -v "$GH_BIN" >/dev/null 2>&1; then
+    return 0
+  fi
+  local is_draft
+  is_draft="$("$GH_BIN" pr view "$pr_url" --json isDraft --jq '.isDraft' 2>/dev/null || true)"
+  if [[ "$is_draft" != "true" ]]; then
+    return 0
+  fi
+  echo "[agent-branch-finish] PR is draft; promoting to ready-for-review (pre-flight passed)." >&2
+  if "$GH_BIN" pr ready "$pr_url" >/dev/null 2>&1; then
+    echo "[agent-branch-finish] PR marked ready-for-review." >&2
+  else
+    echo "[agent-branch-finish] gh pr ready failed; PR left in draft. Promote manually if intended." >&2
+  fi
+}
+
 CLEANUP_AFTER_MERGE="$(normalize_bool "$CLEANUP_AFTER_MERGE_RAW" "1")"
 WAIT_FOR_MERGE="$(normalize_bool "$WAIT_FOR_MERGE_RAW" "1")"
 WAIT_TIMEOUT_SECONDS="$(normalize_int "$WAIT_TIMEOUT_SECONDS_RAW" "1800" "30")"
 WAIT_POLL_SECONDS="$(normalize_int "$WAIT_POLL_SECONDS_RAW" "10" "0")"
 PARENT_GITLINK_AUTO_COMMIT="$(normalize_bool "$PARENT_GITLINK_AUTO_COMMIT_RAW" "1")"
+PREFLIGHT_ENABLED="$(normalize_bool "$PREFLIGHT_ENABLED_RAW" "1")"
+AUTO_PROMOTE_DRAFT="$(normalize_bool "$AUTO_PROMOTE_DRAFT_RAW" "1")"
 
 while [[ $# -gt 0 ]]; do
   case "$1" in
@@ -159,9 +234,29 @@ while [[ $# -gt 0 ]]; do
       AUTO_RESOLVE_MODE_RAW="none"
       shift
       ;;
+    --no-preflight)
+      PREFLIGHT_ENABLED_RAW="false"
+      shift
+      ;;
+    --preflight)
+      PREFLIGHT_ENABLED_RAW="true"
+      shift
+      ;;
+    --preflight-script)
+      PREFLIGHT_SCRIPT_RAW="${2:-}"
+      shift 2
+      ;;
+    --no-auto-promote)
+      AUTO_PROMOTE_DRAFT_RAW="false"
+      shift
+      ;;
+    --auto-promote)
+      AUTO_PROMOTE_DRAFT_RAW="true"
+      shift
+      ;;
     *)
       echo "[agent-branch-finish] Unknown argument: $1" >&2
-      echo "Usage: $0 [--base <branch>] [--branch <branch>] [--no-push] [--cleanup|--no-cleanup] [--wait-for-merge|--no-wait-for-merge] [--wait-timeout-seconds <n>] [--wait-poll-seconds <n>] [--parent-gitlink-commit|--no-parent-gitlink-commit] [--keep-remote-branch|--delete-remote-branch] [--mode auto|direct|pr|--via-pr|--direct-only] [--auto-resolve[=none|safe|full]|--no-auto-resolve]" >&2
+      echo "Usage: $0 [--base <branch>] [--branch <branch>] [--no-push] [--cleanup|--no-cleanup] [--wait-for-merge|--no-wait-for-merge] [--wait-timeout-seconds <n>] [--wait-poll-seconds <n>] [--parent-gitlink-commit|--no-parent-gitlink-commit] [--keep-remote-branch|--delete-remote-branch] [--mode auto|direct|pr|--via-pr|--direct-only] [--auto-resolve[=none|safe|full]|--no-auto-resolve] [--no-preflight|--preflight] [--preflight-script <path>] [--no-auto-promote|--auto-promote]" >&2
       exit 1
       ;;
   esac
@@ -1155,6 +1250,10 @@ run_pr_flow() {
   fi
   echo "[agent-branch-finish] PR URL: ${pr_url}" >&2
 
+  # Pre-flight already passed by the time we reach the PR; promote any
+  # existing draft so the budget-friendly CI gate fires once.
+  maybe_auto_promote_pr "$pr_url"
+
   merge_output=""
   if merge_output="$("$GH_BIN" pr merge "$SOURCE_BRANCH" --squash --delete-branch 2>&1)"; then
     return 0
@@ -1186,6 +1285,9 @@ run_pr_flow() {
 }
 
 if [[ "$PUSH_ENABLED" -eq 1 ]]; then
+  if ! run_preflight "$source_worktree"; then
+    exit 1
+  fi
   if [[ "$MERGE_MODE" != "pr" ]]; then
     maybe_push_changed_submodule_branches "$start_ref" "$SOURCE_BRANCH"
     if ! direct_push_output="$(git -C "$integration_worktree" push origin "HEAD:${BASE_BRANCH}" 2>&1)"; then
diff --git a/templates/scripts/agent-preflight.sh b/templates/scripts/agent-preflight.sh
new file mode 100755
index 0000000..dee5c3f
--- /dev/null
+++ b/templates/scripts/agent-preflight.sh
@@ -0,0 +1,89 @@
+#!/usr/bin/env bash
+# Pre-flight verification gate for gitguardex-managed projects.
+#
+# Runs in the agent's worktree from `gx branch finish` BEFORE the push
+# happens. Returns non-zero to refuse the push so a broken commit
+# never reaches the PR / CI / merge funnel.
+#
+# Auto-detects the project's stack and runs conventional verification:
+#   - Node/pnpm:   pnpm typecheck && pnpm lint && pnpm test (each only
+#                  if the script exists in package.json)
+#   - Node/npm:    npm test (only if defined)
+#   - Rust:        cargo check
+#   - Python:      ruff check (only if ruff is installed)
+#
+# Override per-project by replacing this file (delete the symlink under
+# scripts/agent-preflight.sh and write your own).
+#
+# Skip a single run with `gx branch finish --no-preflight`.
+
+set -euo pipefail
+
+repo_root="$(git rev-parse --show-toplevel 2>/dev/null || pwd)"
+cd "$repo_root"
+
+ran=0
+fail=0
+run_step() {
+  local label="$1"
+  shift
+  echo "[agent-preflight] -> $label"
+  if "$@"; then
+    ran=$((ran + 1))
+    echo "[agent-preflight]    ok"
+  else
+    echo "[agent-preflight] FAIL: $label" >&2
+    fail=1
+  fi
+}
+
+has_package_script() {
+  local script_name="$1"
+  [[ -f package.json ]] || return 1
+  grep -E "\"${script_name}\"\\s*:" package.json >/dev/null 2>&1
+}
+
+# Node detection
+if [[ -f package.json ]]; then
+  pkg_manager=""
+  if command -v pnpm >/dev/null 2>&1 && [[ -f pnpm-lock.yaml ]]; then
+    pkg_manager="pnpm"
+  elif command -v npm >/dev/null 2>&1 && [[ -f package-lock.json ]]; then
+    pkg_manager="npm"
+  fi
+
+  case "$pkg_manager" in
+    pnpm)
+      has_package_script typecheck && run_step "pnpm typecheck" pnpm typecheck
+      has_package_script lint && run_step "pnpm lint" pnpm lint
+      has_package_script test && run_step "pnpm test" pnpm test
+      ;;
+    npm)
+      has_package_script test && run_step "npm test" npm test
+      ;;
+  esac
+fi
+
+# Rust detection
+if [[ -f Cargo.toml ]] && command -v cargo >/dev/null 2>&1; then
+  run_step "cargo check" cargo check --quiet
+fi
+
+# Python detection (ruff if available; pytest is too project-specific to default)
+if [[ -f pyproject.toml ]] && command -v ruff >/dev/null 2>&1; then
+  run_step "ruff check" ruff check .
+fi
+
+if [[ "$ran" -eq 0 ]]; then
+  echo "[agent-preflight] No recognized project stack detected; skipping checks." >&2
+  exit 0
+fi
+
+if [[ "$fail" -ne 0 ]]; then
+  echo "[agent-preflight] Verification failed; refusing push." >&2
+  echo "[agent-preflight] Fix the issues, or re-run with: gx branch finish --no-preflight ..." >&2
+  exit 1
+fi
+
+echo "[agent-preflight] ${ran} step(s) passed."
+exit 0