From 8ad7438f26628abeab1bd5e810c4d55df13b1907 Mon Sep 17 00:00:00 2001
From: Adam Moussa <adam@seahavenind.com>
Date: Sat, 19 Sep 2026 15:22:38 -0400
Subject: [PATCH 1/4] ci: fan out quality gates from this repository

---
 .github/workflows/ci-terraform.yaml |  56 ------------
 .github/workflows/ci.yaml           | 130 ++++++++++++++++++++--------
 .github/workflows/deploy-web.yaml   |   1 -
 AGENTS.md                           |   5 +-
 QUALITY_GATES.md                    |  20 ++---
 README.md                           |  17 ++--
 scripts/governance-check.mjs        |  54 +++++++++---
 terraform/README.md                 |   3 +-
 8 files changed, 154 insertions(+), 132 deletions(-)
 delete mode 100644 .github/workflows/ci-terraform.yaml

diff --git a/.github/workflows/ci-terraform.yaml b/.github/workflows/ci-terraform.yaml
deleted file mode 100644
index a4902d15..00000000
--- a/.github/workflows/ci-terraform.yaml
+++ /dev/null
@@ -1,56 +0,0 @@
-name: Terraform CI
-
-# Static checks only. Plans run in HCP Terraform as speculative VCS runs on
-# the PR (shoc-frontend-new-dev and shoc-frontend-new-staging). Applies are
-# HCP auto-apply on merge to main (dev) and on a vX.Y.Z-staging tag (staging).
-
-on:
-  pull_request:
-    branches: [main, dev]
-    paths:
-      - "terraform/**"
-      - "scripts/**"
-      - ".github/workflows/ci-terraform.yaml"
-      - ".github/workflows/deploy-web.yaml"
-  push:
-    branches: [main]
-    paths:
-      - "terraform/**"
-      - "scripts/**"
-      - ".github/workflows/ci-terraform.yaml"
-
-permissions:
-  contents: read
-
-jobs:
-  terraform:
-    runs-on: ubuntu-latest
-    timeout-minutes: 15
-    steps:
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
-        with:
-          persist-credentials: false
-
-      - uses: hashicorp/setup-terraform@dfe3c3f87815947d99a8997f908cb6525fc44e9e # v4.0.1
-        with:
-          terraform_version: "1.16.0"
-          terraform_wrapper: false
-
-      - name: Terraform fmt
-        run: terraform fmt -check -recursive terraform
-
-      - name: Validate live/dev
-        run: |
-          terraform -chdir=terraform/live/dev init -backend=false -input=false -lockfile=readonly -no-color
-          terraform -chdir=terraform/live/dev validate -no-color
-
-      - name: Validate live/staging
-        run: |
-          terraform -chdir=terraform/live/staging init -backend=false -input=false -lockfile=readonly -no-color
-          terraform -chdir=terraform/live/staging validate -no-color
-
-      - name: Import plan guard tests
-        run: python3 scripts/test-terraform-import-plan-check.py
-
-      - name: App/Terraform isolation tests
-        run: python3 scripts/test_check_app_terraform_isolation.py
diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index ef6ccb02..f725d6fe 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -13,25 +13,81 @@ on:
 permissions:
   contents: read
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+
 jobs:
-  build-and-test:
-    name: Build and test
-    # Org reusable workflow (Node 24): format check, lint, build, unit tests.
-    uses: Sea-Haven-Industries/.github/.github/workflows/ci-typescript-frontend.yaml@af0f002e14a08cdbfd879c1183bfe7eb2604bce9 # v1.0.8
-    with:
-      node-version: "24"
+  static:
+    name: static
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/setup-node@820762786026740c76f36085b0efc47a31fe5020 # v7.0.0
+        with:
+          node-version: "24"
+          cache: npm
+      - run: npm ci
+      - run: npm run format:check
+      - run: npm run lint
+
+  build:
+    name: build
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/setup-node@820762786026740c76f36085b0efc47a31fe5020 # v7.0.0
+        with:
+          node-version: "24"
+          cache: npm
+      - run: npm ci
+      - run: npm run build
+
+  unit:
+    name: unit
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        shard: [1, 2]
+    steps:
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/setup-node@820762786026740c76f36085b0efc47a31fe5020 # v7.0.0
+        with:
+          node-version: "24"
+          cache: npm
+      - run: npm ci
+      - run: npm test -- --shard=${{ matrix.shard }}/2
+
+  visual:
+    name: Visual regression
+    runs-on: ubuntu-latest
+    container: mcr.microsoft.com/playwright:v1.61.1-noble
+    steps:
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/setup-node@820762786026740c76f36085b0efc47a31fe5020 # v7.0.0
+        with:
+          node-version: "24"
+          cache: npm
+      - run: npm ci
+      - run: npm run test:e2e:visual
+      - name: Upload visual diff artifacts
+        if: failure()
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
+        with:
+          name: visual-regression-diffs
+          path: |
+            test-results/visual
+            playwright-report-visual
+          if-no-files-found: ignore
+          retention-days: 14
 
   governance:
-    # Repo-owned guarantee that every frontend quality gate runs from this
-    # repository, independent of (and in addition to) the reusable workflow.
-    # `npm run verify` is the single command that chains: format check, lint
-    # (--max-warnings=0), type-check + build, unit tests, then the governance
-    # checks in scripts/governance-check.mjs (godfile ratchet, changed-file
-    # maintainability gate, Terraform fmt/validate, Terraform import-plan
-    # guard, HCP run guard, CloudFront verify, GitHub workflow shell, and G13
-    # app/Terraform isolation). Runs on PRs to main or dev; push is main only.
-    # If the reusable workflow is later confirmed to run every gate, this job
-    # can be slimmed to `npm run governance`.
+    # Repo-owned gates: godfile ratchet, changed-file maintainability,
+    # Terraform fmt/validate, import-plan guard, HCP run guard, CloudFront
+    # verify, GitHub workflow shell, isolation classifier tests, and live G13
+    # (pull_request and local only). Format, lint, build, and unit tests run
+    # in the parallel jobs above, not here.
     #
     # GOVERNANCE_BASE points the changed-file gate at the right diff:
     #   PR  -> the PR target branch (origin/<base_ref>)
@@ -86,29 +142,29 @@ jobs:
           tar -xzf actionlint.tar.gz actionlint
           sudo mv actionlint /usr/local/bin/actionlint
       - run: npm ci
-      - run: npm run verify
+      - run: npm run governance
         env:
           GOVERNANCE_BASE: ${{ steps.governance-ref.outputs.base }}
 
-  visual-regression:
-    name: Visual regression
+  ci-complete:
+    name: ci-complete
+    if: always()
+    needs: [static, build, unit, visual, governance]
     runs-on: ubuntu-latest
-    container: mcr.microsoft.com/playwright:v1.61.1-noble
     steps:
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
-      - uses: actions/setup-node@820762786026740c76f36085b0efc47a31fe5020 # v7.0.0
-        with:
-          node-version: "24"
-          cache: npm
-      - run: npm ci
-      - run: npm run test:e2e:visual
-      - name: Upload visual diff artifacts
-        if: failure()
-        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
-        with:
-          name: visual-regression-diffs
-          path: |
-            test-results/visual
-            playwright-report-visual
-          if-no-files-found: ignore
-          retention-days: 14
+      - name: All required jobs passed
+        shell: bash
+        env:
+          RESULTS: ${{ join(needs.*.result, ' ') }}
+        run: |
+          set -euo pipefail
+          failed=0
+          for result in ${RESULTS}; do
+            if [[ "${result}" != "success" ]]; then
+              failed=1
+            fi
+          done
+          if [[ "${failed}" -ne 0 ]]; then
+            echo "Required jobs did not all succeed: ${RESULTS}"
+            exit 1
+          fi
diff --git a/.github/workflows/deploy-web.yaml b/.github/workflows/deploy-web.yaml
index 943cad51..aaa1ac1e 100644
--- a/.github/workflows/deploy-web.yaml
+++ b/.github/workflows/deploy-web.yaml
@@ -28,7 +28,6 @@ on:
       - "docs/**"
       - "**/*.md"
       - ".github/workflows/ci.yaml"
-      - ".github/workflows/ci-terraform.yaml"
       - ".github/workflows/deploy-web.yaml"
   release:
     types: [published]
diff --git a/AGENTS.md b/AGENTS.md
index 68229d76..51a13d7b 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -30,8 +30,9 @@ This chains the full set: Prettier check, ESLint (`--max-warnings=0`), TypeScrip
 build (`tsc -b && vite build`), unit tests (`vitest run`), and the governance
 checks (`npm run governance`), including G13 app/Terraform isolation. **Do not
 claim a task is done until `npm run verify` is green locally.** CI runs the same
-`npm run verify` in a repo-owned `governance` job, so a green local run mirrors
-CI.
+gates as parallel jobs in [`.github/workflows/ci.yaml`](.github/workflows/ci.yaml)
+(`static`, `build`, `unit`, `visual`, `governance`) with `ci-complete` failing if
+any of those jobs did not succeed.
 
 ## Non-negotiable rules (enforced; do not work around)
 
diff --git a/QUALITY_GATES.md b/QUALITY_GATES.md
index 75693239..fcaacb21 100644
--- a/QUALITY_GATES.md
+++ b/QUALITY_GATES.md
@@ -31,7 +31,7 @@ isolation). A task is not done until this is green.
 | HCP run guard                       | `npm run test:hcp-run-guard` → `scripts/test-hcp-run-guard.py`                                              | `governance` + CI      | Workspace invariants + apply reconcile         |
 | CloudFront release verify           | `npm run test:cloudfront-release-verify` → `scripts/test-verify-cloudfront-release.sh`                      | `governance` + CI      | Stubbed aws/curl                               |
 | GitHub workflow shell               | `npm run test:github-workflows` → `scripts/check-github-workflows.sh`                                       | `governance` + CI      | `bash -n` + actionlint                         |
-| G13 App/Terraform isolation         | `python3 scripts/check_app_terraform_isolation.py` vs `GOVERNANCE_BASE`                                     | `governance` + CI      | Deployable app files vs `terraform/`           |
+| G13 App/Terraform isolation         | `python3 scripts/check_app_terraform_isolation.py` vs merge-base of `GOVERNANCE_BASE`                       | `governance` + CI      | Deployable app files vs `terraform/` (live classifier: PR + local) |
 
 ## No-false-pass guarantees
 
@@ -60,15 +60,15 @@ isolation). A task is not done until this is green.
 
 - **Locally:** `npm run verify`. `lint-staged` (via Husky) re-runs ESLint +
   Prettier on staged files at commit; commitlint enforces Conventional Commits.
-- **CI ([`.github/workflows/ci.yaml`](.github/workflows/ci.yaml)):** the org
-  reusable workflow (`ci-typescript-frontend.yaml`, Node 24) runs
-  format/lint/build/tests, **and** a repo-owned `governance` job runs
-  `npm run verify` (with Terraform 1.16.0 installed) so the maintainability
-  ratchets and repository gates are guaranteed from this repository regardless
-  of the reusable workflow.
-- **Terraform CI ([`.github/workflows/ci-terraform.yaml`](.github/workflows/ci-terraform.yaml)):**
-  fmt, `init -backend=false`, validate, import-plan unit tests, and G13
-  classifier unit tests on `terraform/**` changes for PRs to `main` or `dev`.
+- **CI ([`.github/workflows/ci.yaml`](.github/workflows/ci.yaml)):** this
+  repository owns every job. `static` (`format:check` + `lint`), `build`
+  (`tsc -b && vite build`), `unit` (`vitest run` in two shards), `visual`
+  (Playwright visual), and `governance` (`npm run governance`, with Terraform
+  1.16.0) run in parallel. `ci-complete` fails unless all of those jobs
+  succeeded and is the required merge-queue check. Live G13 runs on
+  `pull_request` and locally; it skips `merge_group` and `push`. Terraform
+  fmt/validate and the related unit tests run inside `governance` on every
+  event.
 
 ## Toolchain pin
 
diff --git a/README.md b/README.md
index 4d0edbc3..76040f38 100644
--- a/README.md
+++ b/README.md
@@ -131,8 +131,8 @@ commitlint enforces conventional commit messages. Run `npx tsc --noEmit` (or
   rejects anything else at commit time.
 - Open PRs against `main`. The PR body uses the three-section layout the
   template pre-fills: Summary, Changes and value, Ticket. `main` needs the
-  `governance` and `Build and test / ci` checks and an approving review from a
-  code owner (`@Sea-Haven-Industries/internal-dev`); new pushes dismiss stale
+  `ci-complete` check and an approving review from a code owner
+  (`@Sea-Haven-Industries/internal-dev`); new pushes dismiss stale
   approvals. PRs merge through the merge queue, so a branch does not need to
   be updated with `main` before it merges. Merged branches are deleted
   automatically.
@@ -148,19 +148,12 @@ commitlint enforces conventional commit messages. Run `npx tsc --noEmit` (or
 No stored AWS keys — OIDC only. Infrastructure and content deploy separately:
 
 - **CI** ([`.github/workflows/ci.yaml`](.github/workflows/ci.yaml)) — on push
-  and PRs to `main`, calls
-  `Sea-Haven-Industries/.github` → `ci-typescript-frontend.yaml` (Node 24):
-  format check, lint, build, tests; **and** runs a repo-owned `governance` job
-  that calls `npm run verify` so every gate (including the maintainability
-  ratchets in [`scripts/governance-check.mjs`](scripts/governance-check.mjs)
-  and the Terraform gates) is guaranteed from this repository. Conventions
-  and gates are documented under
+  and PRs to `main`, runs format, lint, build, sharded unit tests, visual
+  regression, and `npm run governance` as parallel jobs, then `ci-complete`.
+  Conventions and gates are documented under
   [`AGENTS.md`](AGENTS.md), [`QUALITY_GATES.md`](QUALITY_GATES.md),
   [`ARCHITECTURE_AND_CODE_QUALITY.md`](ARCHITECTURE_AND_CODE_QUALITY.md), and
   [`REVIEW_AND_PR_FRAMEWORK.md`](REVIEW_AND_PR_FRAMEWORK.md).
-- **Terraform CI**
-  ([`.github/workflows/ci-terraform.yaml`](.github/workflows/ci-terraform.yaml))
-  — fmt, `init -backend=false`, validate, and import-plan tests.
 - **SPA content** ([`.github/workflows/deploy-web.yaml`](.github/workflows/deploy-web.yaml))
   — push to `main` deploys `dev`; a published `vX.Y.Z-staging` release deploys
   `staging`. Syncs `dist/` to the bucket root and invalidates `/*`.
diff --git a/scripts/governance-check.mjs b/scripts/governance-check.mjs
index 46172487..84b4c5cf 100644
--- a/scripts/governance-check.mjs
+++ b/scripts/governance-check.mjs
@@ -218,13 +218,23 @@ function runRepositoryGate(label, script) {
   return { label, status: result.status, error: result.error };
 }
 
+function shouldRunLiveIsolation() {
+  const eventName = process.env.GITHUB_EVENT_NAME;
+  return !eventName || eventName === "pull_request";
+}
+
 function runIsolationGate(baseRef) {
-  const files = gitLines(["diff", "--name-only", "--diff-filter=ACMR", baseRef, "HEAD"]);
-  return spawnSync("python3", ["scripts/check_app_terraform_isolation.py"], {
+  // Diff from the merge base, not the moving base tip. A two-dot diff against
+  // a branch that has advanced reports everything the base gained after the
+  // branch point as if this change reverted it.
+  const mergeBase = gitText(["merge-base", baseRef, "HEAD"]);
+  const files = gitLines(["diff", "--name-only", "--diff-filter=ACMR", mergeBase, "HEAD"]);
+  const result = spawnSync("python3", ["scripts/check_app_terraform_isolation.py"], {
     cwd: ROOT,
     encoding: "utf8",
     input: `${files.join("\n")}\n`,
   });
+  return { ...result, mergeBase };
 }
 
 function main() {
@@ -326,22 +336,40 @@ function main() {
   }
 
   console.log("─".repeat(64));
-  console.log(`G13: application and Terraform isolation (${baseRef ?? "no base"}..HEAD)`);
-  if (!baseRef) {
+  if (!shouldRunLiveIsolation()) {
+    console.log(
+      `G13: skipped — live isolation is a pull-request property (event: ${process.env.GITHUB_EVENT_NAME})`,
+    );
+  } else if (!baseRef) {
+    console.log("G13: application and Terraform isolation (no base...HEAD)");
     console.log("  FAIL (no valid base ref)");
     failures.push(
       "G13: base ref is required but was not found. Set GOVERNANCE_BASE to a valid commit or fetch origin/dev.",
     );
   } else {
-    const isolation = runIsolationGate(baseRef);
-    if (isolation.error) {
-      console.log("  FAIL (could not start)");
-      failures.push(`G13: could not start: ${isolation.error.message}`);
-    } else {
-      const output = `${isolation.stdout ?? ""}${isolation.stderr ?? ""}`.trim();
-      if (output) console.log(`  ${output.replaceAll("\n", "\n  ")}`);
-      if (isolation.status !== 0) {
-        failures.push("G13: do not mix deployable application files with terraform/");
+    let isolation;
+    try {
+      isolation = runIsolationGate(baseRef);
+    } catch (error) {
+      console.log(`G13: application and Terraform isolation (${baseRef}...HEAD)`);
+      console.log("  FAIL (could not resolve merge base)");
+      const message = error instanceof Error ? error.message : String(error);
+      failures.push(`G13: could not resolve merge base against HEAD: ${message}`);
+    }
+    if (isolation) {
+      const mergeBase = isolation.mergeBase ?? "unresolvable";
+      console.log(
+        `G13: application and Terraform isolation (${baseRef}...HEAD, merge base ${mergeBase.slice(0, 7)})`,
+      );
+      if (isolation.error) {
+        console.log("  FAIL (could not start)");
+        failures.push(`G13: could not start: ${isolation.error.message}`);
+      } else {
+        const output = `${isolation.stdout ?? ""}${isolation.stderr ?? ""}`.trim();
+        if (output) console.log(`  ${output.replaceAll("\n", "\n  ")}`);
+        if (isolation.status !== 0) {
+          failures.push("G13: do not mix deployable application files with terraform/");
+        }
       }
     }
   }
diff --git a/terraform/README.md b/terraform/README.md
index a2922962..ddeb0bc5 100644
--- a/terraform/README.md
+++ b/terraform/README.md
@@ -56,7 +56,8 @@ bash scripts/test-verify-cloudfront-release.sh
 
 PRs cannot mix `terraform/` with deployable application files. Workflow, docs,
 and gate-script changes may travel with either side. G13 is
-`python3 scripts/check_app_terraform_isolation.py` against the PR base.
+`python3 scripts/check_app_terraform_isolation.py` against the merge base of
+the PR.
 
 `npm run test:terraform` and `npm run verify` wrap the same gates. They never
 create an HCP run or touch AWS.

From af0ae60b80e5d0d15bf1557f5e9841a4be883d6e Mon Sep 17 00:00:00 2001
From: Adam Moussa <adam@seahavenind.com>
Date: Sat, 19 Sep 2026 15:41:10 -0400
Subject: [PATCH 2/4] ci: shard unit tests four ways

---
 .github/workflows/ci.yaml | 4 ++--
 QUALITY_GATES.md          | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index f725d6fe..f44095b9 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -49,7 +49,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        shard: [1, 2]
+        shard: [1, 2, 3, 4]
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
       - uses: actions/setup-node@820762786026740c76f36085b0efc47a31fe5020 # v7.0.0
@@ -57,7 +57,7 @@ jobs:
           node-version: "24"
           cache: npm
       - run: npm ci
-      - run: npm test -- --shard=${{ matrix.shard }}/2
+      - run: npm test -- --shard=${{ matrix.shard }}/4
 
   visual:
     name: Visual regression
diff --git a/QUALITY_GATES.md b/QUALITY_GATES.md
index fcaacb21..a8e4885e 100644
--- a/QUALITY_GATES.md
+++ b/QUALITY_GATES.md
@@ -62,7 +62,7 @@ isolation). A task is not done until this is green.
   Prettier on staged files at commit; commitlint enforces Conventional Commits.
 - **CI ([`.github/workflows/ci.yaml`](.github/workflows/ci.yaml)):** this
   repository owns every job. `static` (`format:check` + `lint`), `build`
-  (`tsc -b && vite build`), `unit` (`vitest run` in two shards), `visual`
+  (`tsc -b && vite build`), `unit` (`vitest run` in four shards), `visual`
   (Playwright visual), and `governance` (`npm run governance`, with Terraform
   1.16.0) run in parallel. `ci-complete` fails unless all of those jobs
   succeeded and is the required merge-queue check. Live G13 runs on

From ec9812ae8d1dfb39ea99807b2c49c175f887dca1 Mon Sep 17 00:00:00 2001
From: Adam Moussa <166072409+amoussa1229@users.noreply.github.com>
Date: Sat, 19 Sep 2026 19:47:08 +0000
Subject: [PATCH 3/4] fix(style): correct line-wrapping formatting errors

---
 QUALITY_GATES.md | 34 +++++++++++++++++-----------------
 1 file changed, 17 insertions(+), 17 deletions(-)

diff --git a/QUALITY_GATES.md b/QUALITY_GATES.md
index a8e4885e..7dcc3bbc 100644
--- a/QUALITY_GATES.md
+++ b/QUALITY_GATES.md
@@ -14,23 +14,23 @@ isolation). A task is not done until this is green.
 
 ## Gate matrix
 
-| Gate                                | Command / rule source                                                                                       | Enforced by            | Scope                                          |
-| ----------------------------------- | ----------------------------------------------------------------------------------------------------------- | ---------------------- | ---------------------------------------------- |
-| Formatting                          | `npm run format:check` (Prettier)                                                                           | `verify` + lint-staged | Whole repo                                     |
-| Lint, zero warnings                 | `npm run lint` → `eslint . --max-warnings=0`                                                                | `verify` + CI          | Governed TS/TSX (`eslint.config.js`)           |
-| Type-check + production build       | `npm run build` → `tsc -b && vite build`                                                                    | `verify` + CI          | Whole app                                      |
-| Unit tests                          | `npm test` → `vitest run`                                                                                   | `verify` + CI          | `src/test/**`, `config/**/*.test.ts`           |
-| Conditional rendering (no `: null`) | `no-restricted-syntax` in `eslint.config.js`                                                                | lint                   | Governed TSX                                   |
-| Boolean-only JSX `&&`               | `seahaven/no-non-boolean-jsx-and` (type-aware) in `eslint-rules/`                                           | lint                   | Governed TSX                                   |
-| Shared `Text` typography            | `no-restricted-syntax` (raw `p`/`h1`–`h6`) + `seahaven/no-vp-error-outside-text`                            | lint                   | Governed TSX                                   |
-| Hooks correctness                   | `eslint-plugin-react-hooks` recommended (incl. `exhaustive-deps`) under zero-warnings                       | lint                   | Governed TS/TSX                                |
-| Godfile ratchet (file length)       | `scripts/governance-check.mjs` + `scripts/governance-baseline.json`                                         | `governance`           | `src/**`, `config/**` (non-test)               |
-| Changed-file maintainability        | `scripts/governance-check.mjs` → ESLint (`complexity`, `max-lines-per-function`, `max-params`, `max-depth`) | `governance`           | Changed TS/TSX vs base ref                     |
-| Terraform import-plan contract      | `npm run test:terraform-import-plan` → `scripts/test-terraform-import-plan-check.py`                        | `governance` + CI      | Synthetic plan JSON + canonical maps           |
-| Terraform formatting/validation     | `npm run test:terraform` → `scripts/terraform-validate.mjs`                                                 | `governance` + CI      | `terraform/live/dev`, `terraform/live/staging` |
-| HCP run guard                       | `npm run test:hcp-run-guard` → `scripts/test-hcp-run-guard.py`                                              | `governance` + CI      | Workspace invariants + apply reconcile         |
-| CloudFront release verify           | `npm run test:cloudfront-release-verify` → `scripts/test-verify-cloudfront-release.sh`                      | `governance` + CI      | Stubbed aws/curl                               |
-| GitHub workflow shell               | `npm run test:github-workflows` → `scripts/check-github-workflows.sh`                                       | `governance` + CI      | `bash -n` + actionlint                         |
+| Gate                                | Command / rule source                                                                                       | Enforced by            | Scope                                                              |
+| ----------------------------------- | ----------------------------------------------------------------------------------------------------------- | ---------------------- | ------------------------------------------------------------------ |
+| Formatting                          | `npm run format:check` (Prettier)                                                                           | `verify` + lint-staged | Whole repo                                                         |
+| Lint, zero warnings                 | `npm run lint` → `eslint . --max-warnings=0`                                                                | `verify` + CI          | Governed TS/TSX (`eslint.config.js`)                               |
+| Type-check + production build       | `npm run build` → `tsc -b && vite build`                                                                    | `verify` + CI          | Whole app                                                          |
+| Unit tests                          | `npm test` → `vitest run`                                                                                   | `verify` + CI          | `src/test/**`, `config/**/*.test.ts`                               |
+| Conditional rendering (no `: null`) | `no-restricted-syntax` in `eslint.config.js`                                                                | lint                   | Governed TSX                                                       |
+| Boolean-only JSX `&&`               | `seahaven/no-non-boolean-jsx-and` (type-aware) in `eslint-rules/`                                           | lint                   | Governed TSX                                                       |
+| Shared `Text` typography            | `no-restricted-syntax` (raw `p`/`h1`–`h6`) + `seahaven/no-vp-error-outside-text`                            | lint                   | Governed TSX                                                       |
+| Hooks correctness                   | `eslint-plugin-react-hooks` recommended (incl. `exhaustive-deps`) under zero-warnings                       | lint                   | Governed TS/TSX                                                    |
+| Godfile ratchet (file length)       | `scripts/governance-check.mjs` + `scripts/governance-baseline.json`                                         | `governance`           | `src/**`, `config/**` (non-test)                                   |
+| Changed-file maintainability        | `scripts/governance-check.mjs` → ESLint (`complexity`, `max-lines-per-function`, `max-params`, `max-depth`) | `governance`           | Changed TS/TSX vs base ref                                         |
+| Terraform import-plan contract      | `npm run test:terraform-import-plan` → `scripts/test-terraform-import-plan-check.py`                        | `governance` + CI      | Synthetic plan JSON + canonical maps                               |
+| Terraform formatting/validation     | `npm run test:terraform` → `scripts/terraform-validate.mjs`                                                 | `governance` + CI      | `terraform/live/dev`, `terraform/live/staging`                     |
+| HCP run guard                       | `npm run test:hcp-run-guard` → `scripts/test-hcp-run-guard.py`                                              | `governance` + CI      | Workspace invariants + apply reconcile                             |
+| CloudFront release verify           | `npm run test:cloudfront-release-verify` → `scripts/test-verify-cloudfront-release.sh`                      | `governance` + CI      | Stubbed aws/curl                                                   |
+| GitHub workflow shell               | `npm run test:github-workflows` → `scripts/check-github-workflows.sh`                                       | `governance` + CI      | `bash -n` + actionlint                                             |
 | G13 App/Terraform isolation         | `python3 scripts/check_app_terraform_isolation.py` vs merge-base of `GOVERNANCE_BASE`                       | `governance` + CI      | Deployable app files vs `terraform/` (live classifier: PR + local) |
 
 ## No-false-pass guarantees

From cc7ecb9b5a517f1266aef1114307b74de507a5cd Mon Sep 17 00:00:00 2001
From: Cursor Agent <cursoragent@cursor.com>
Date: Sat, 19 Sep 2026 20:20:30 +0000
Subject: [PATCH 4/4] fix(ci): classify G13 per queued PR on merge_group

Run live isolation on the merge-queue event so ci-complete actually
gates mixed change sets, without treating the group union as one PR.
---
 .github/workflows/ci.yaml           |   3 +-
 QUALITY_GATES.md                    |  44 ++++++------
 README.md                           |   7 +-
 package.json                        |   2 +-
 scripts/g13-live-isolation.mjs      |  29 ++++++++
 scripts/governance-check.mjs        | 103 ++++++++++++++++++++--------
 scripts/test-g13-live-isolation.mjs |  73 ++++++++++++++++++++
 terraform/README.md                 |   2 +-
 8 files changed, 207 insertions(+), 56 deletions(-)
 create mode 100644 scripts/g13-live-isolation.mjs
 create mode 100644 scripts/test-g13-live-isolation.mjs

diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index f44095b9..5e2c75db 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -86,7 +86,8 @@ jobs:
     # Repo-owned gates: godfile ratchet, changed-file maintainability,
     # Terraform fmt/validate, import-plan guard, HCP run guard, CloudFront
     # verify, GitHub workflow shell, isolation classifier tests, and live G13
-    # (pull_request and local only). Format, lint, build, and unit tests run
+    # (pull_request, merge_group per queued PR, and local). Format, lint, build,
+    # and unit tests run
     # in the parallel jobs above, not here.
     #
     # GOVERNANCE_BASE points the changed-file gate at the right diff:
diff --git a/QUALITY_GATES.md b/QUALITY_GATES.md
index 7dcc3bbc..a5596f8b 100644
--- a/QUALITY_GATES.md
+++ b/QUALITY_GATES.md
@@ -14,24 +14,24 @@ isolation). A task is not done until this is green.
 
 ## Gate matrix
 
-| Gate                                | Command / rule source                                                                                       | Enforced by            | Scope                                                              |
-| ----------------------------------- | ----------------------------------------------------------------------------------------------------------- | ---------------------- | ------------------------------------------------------------------ |
-| Formatting                          | `npm run format:check` (Prettier)                                                                           | `verify` + lint-staged | Whole repo                                                         |
-| Lint, zero warnings                 | `npm run lint` → `eslint . --max-warnings=0`                                                                | `verify` + CI          | Governed TS/TSX (`eslint.config.js`)                               |
-| Type-check + production build       | `npm run build` → `tsc -b && vite build`                                                                    | `verify` + CI          | Whole app                                                          |
-| Unit tests                          | `npm test` → `vitest run`                                                                                   | `verify` + CI          | `src/test/**`, `config/**/*.test.ts`                               |
-| Conditional rendering (no `: null`) | `no-restricted-syntax` in `eslint.config.js`                                                                | lint                   | Governed TSX                                                       |
-| Boolean-only JSX `&&`               | `seahaven/no-non-boolean-jsx-and` (type-aware) in `eslint-rules/`                                           | lint                   | Governed TSX                                                       |
-| Shared `Text` typography            | `no-restricted-syntax` (raw `p`/`h1`–`h6`) + `seahaven/no-vp-error-outside-text`                            | lint                   | Governed TSX                                                       |
-| Hooks correctness                   | `eslint-plugin-react-hooks` recommended (incl. `exhaustive-deps`) under zero-warnings                       | lint                   | Governed TS/TSX                                                    |
-| Godfile ratchet (file length)       | `scripts/governance-check.mjs` + `scripts/governance-baseline.json`                                         | `governance`           | `src/**`, `config/**` (non-test)                                   |
-| Changed-file maintainability        | `scripts/governance-check.mjs` → ESLint (`complexity`, `max-lines-per-function`, `max-params`, `max-depth`) | `governance`           | Changed TS/TSX vs base ref                                         |
-| Terraform import-plan contract      | `npm run test:terraform-import-plan` → `scripts/test-terraform-import-plan-check.py`                        | `governance` + CI      | Synthetic plan JSON + canonical maps                               |
-| Terraform formatting/validation     | `npm run test:terraform` → `scripts/terraform-validate.mjs`                                                 | `governance` + CI      | `terraform/live/dev`, `terraform/live/staging`                     |
-| HCP run guard                       | `npm run test:hcp-run-guard` → `scripts/test-hcp-run-guard.py`                                              | `governance` + CI      | Workspace invariants + apply reconcile                             |
-| CloudFront release verify           | `npm run test:cloudfront-release-verify` → `scripts/test-verify-cloudfront-release.sh`                      | `governance` + CI      | Stubbed aws/curl                                                   |
-| GitHub workflow shell               | `npm run test:github-workflows` → `scripts/check-github-workflows.sh`                                       | `governance` + CI      | `bash -n` + actionlint                                             |
-| G13 App/Terraform isolation         | `python3 scripts/check_app_terraform_isolation.py` vs merge-base of `GOVERNANCE_BASE`                       | `governance` + CI      | Deployable app files vs `terraform/` (live classifier: PR + local) |
+| Gate                                | Command / rule source                                                                                                         | Enforced by            | Scope                                                               |
+| ----------------------------------- | ----------------------------------------------------------------------------------------------------------------------------- | ---------------------- | ------------------------------------------------------------------- |
+| Formatting                          | `npm run format:check` (Prettier)                                                                                             | `verify` + lint-staged | Whole repo                                                          |
+| Lint, zero warnings                 | `npm run lint` → `eslint . --max-warnings=0`                                                                                  | `verify` + CI          | Governed TS/TSX (`eslint.config.js`)                                |
+| Type-check + production build       | `npm run build` → `tsc -b && vite build`                                                                                      | `verify` + CI          | Whole app                                                           |
+| Unit tests                          | `npm test` → `vitest run`                                                                                                     | `verify` + CI          | `src/test/**`, `config/**/*.test.ts`                                |
+| Conditional rendering (no `: null`) | `no-restricted-syntax` in `eslint.config.js`                                                                                  | lint                   | Governed TSX                                                        |
+| Boolean-only JSX `&&`               | `seahaven/no-non-boolean-jsx-and` (type-aware) in `eslint-rules/`                                                             | lint                   | Governed TSX                                                        |
+| Shared `Text` typography            | `no-restricted-syntax` (raw `p`/`h1`–`h6`) + `seahaven/no-vp-error-outside-text`                                              | lint                   | Governed TSX                                                        |
+| Hooks correctness                   | `eslint-plugin-react-hooks` recommended (incl. `exhaustive-deps`) under zero-warnings                                         | lint                   | Governed TS/TSX                                                     |
+| Godfile ratchet (file length)       | `scripts/governance-check.mjs` + `scripts/governance-baseline.json`                                                           | `governance`           | `src/**`, `config/**` (non-test)                                    |
+| Changed-file maintainability        | `scripts/governance-check.mjs` → ESLint (`complexity`, `max-lines-per-function`, `max-params`, `max-depth`)                   | `governance`           | Changed TS/TSX vs base ref                                          |
+| Terraform import-plan contract      | `npm run test:terraform-import-plan` → `scripts/test-terraform-import-plan-check.py`                                          | `governance` + CI      | Synthetic plan JSON + canonical maps                                |
+| Terraform formatting/validation     | `npm run test:terraform` → `scripts/terraform-validate.mjs`                                                                   | `governance` + CI      | `terraform/live/dev`, `terraform/live/staging`                      |
+| HCP run guard                       | `npm run test:hcp-run-guard` → `scripts/test-hcp-run-guard.py`                                                                | `governance` + CI      | Workspace invariants + apply reconcile                              |
+| CloudFront release verify           | `npm run test:cloudfront-release-verify` → `scripts/test-verify-cloudfront-release.sh`                                        | `governance` + CI      | Stubbed aws/curl                                                    |
+| GitHub workflow shell               | `npm run test:github-workflows` → `scripts/check-github-workflows.sh`                                                         | `governance` + CI      | `bash -n` + actionlint                                              |
+| G13 App/Terraform isolation         | `python3 scripts/check_app_terraform_isolation.py` vs merge-base of `GOVERNANCE_BASE` (merge_group: each first-parent commit) | `governance` + CI      | Deployable app files vs `terraform/` (live: PR, merge_group, local) |
 
 ## No-false-pass guarantees
 
@@ -66,9 +66,11 @@ isolation). A task is not done until this is green.
   (Playwright visual), and `governance` (`npm run governance`, with Terraform
   1.16.0) run in parallel. `ci-complete` fails unless all of those jobs
   succeeded and is the required merge-queue check. Live G13 runs on
-  `pull_request` and locally; it skips `merge_group` and `push`. Terraform
-  fmt/validate and the related unit tests run inside `governance` on every
-  event.
+  `pull_request` (merge-base range), `merge_group` (each queued PR as a
+  first-parent commit), and locally. It skips `push`. A Terraform-only PR
+  stacked with an app-only PR still passes; a mixed change set still fails.
+  Terraform fmt/validate and the related unit tests run inside `governance` on
+  every event.
 
 ## Toolchain pin
 
diff --git a/README.md b/README.md
index 76040f38..974e0bf1 100644
--- a/README.md
+++ b/README.md
@@ -136,9 +136,10 @@ commitlint enforces conventional commit messages. Run `npx tsc --noEmit` (or
   approvals. PRs merge through the merge queue, so a branch does not need to
   be updated with `main` before it merges. Merged branches are deleted
   automatically.
-- PRs cannot mix `terraform/` with deployable application files (G13). Workflow,
-  docs, and gate-script changes may travel with either side. `deploy-web.yaml`
-  still ignores `terraform/**` so a Terraform-only merge does not sync the bucket.
+- A change set cannot mix `terraform/` with deployable application files (G13),
+  including each queued PR on the merge-group check. Workflow, docs, and
+  gate-script changes may travel with either side. `deploy-web.yaml` still
+  ignores `terraform/**` so a Terraform-only merge does not sync the bucket.
 - Promotion flow: merge to `main` deploys `dev.seahaven.com`. A person cuts
   `vX.Y.Z-staging` for `staging.seahaven.com`. Core `vX.Y.Z` waits until a
   prod distribution exists.
diff --git a/package.json b/package.json
index 3ce507f5..b1fc3700 100644
--- a/package.json
+++ b/package.json
@@ -17,7 +17,7 @@
     "test:hcp-run-guard": "python3 scripts/test-hcp-run-guard.py",
     "test:cloudfront-release-verify": "bash scripts/test-verify-cloudfront-release.sh",
     "test:github-workflows": "bash scripts/check-github-workflows.sh",
-    "test:app-terraform-isolation": "python3 scripts/test_check_app_terraform_isolation.py",
+    "test:app-terraform-isolation": "python3 scripts/test_check_app_terraform_isolation.py && node --test scripts/test-g13-live-isolation.mjs",
     "lint": "eslint . --max-warnings=0",
     "lint:fix": "eslint . --fix --max-warnings=0",
     "format": "prettier --write .",
diff --git a/scripts/g13-live-isolation.mjs b/scripts/g13-live-isolation.mjs
new file mode 100644
index 00000000..3e2d8f65
--- /dev/null
+++ b/scripts/g13-live-isolation.mjs
@@ -0,0 +1,29 @@
+/**
+ * Live G13 scheduling and how a GitHub event is split into change sets.
+ *
+ * Isolation is a per-change rule. pull_request and local runs classify the
+ * merge-base...HEAD range (one PR). merge_group classifies each first-parent
+ * commit vs its parent (one queued PR per squash or merge-commit). The group
+ * union is not a change set: a Terraform-only PR stacked with an app-only PR
+ * must still pass. push is not classified; landing already happened.
+ */
+
+export function shouldRunLiveIsolation(eventName) {
+  return !eventName || eventName === "pull_request" || eventName === "merge_group";
+}
+
+export function usesPerCommitIsolation(eventName) {
+  return eventName === "merge_group";
+}
+
+/**
+ * File lists to run through check_app_terraform_isolation.py.
+ * `commitDiffs` is first-parent order (oldest first); ignored except on
+ * merge_group.
+ */
+export function liveIsolationFileSets(eventName, rangeFiles, commitDiffs) {
+  if (usesPerCommitIsolation(eventName)) {
+    return commitDiffs.map((commit) => commit.files);
+  }
+  return [rangeFiles];
+}
diff --git a/scripts/governance-check.mjs b/scripts/governance-check.mjs
index 84b4c5cf..025489cb 100644
--- a/scripts/governance-check.mjs
+++ b/scripts/governance-check.mjs
@@ -3,6 +3,8 @@ import { existsSync, readFileSync } from "node:fs";
 import path from "node:path";
 import { fileURLToPath } from "node:url";
 
+import { shouldRunLiveIsolation, usesPerCommitIsolation } from "./g13-live-isolation.mjs";
+
 const SCRIPT_DIR = path.dirname(fileURLToPath(import.meta.url));
 const ROOT = path.resolve(SCRIPT_DIR, "..");
 const BASELINE_PATH = path.join(SCRIPT_DIR, "governance-baseline.json");
@@ -218,23 +220,77 @@ function runRepositoryGate(label, script) {
   return { label, status: result.status, error: result.error };
 }
 
-function shouldRunLiveIsolation() {
-  const eventName = process.env.GITHUB_EVENT_NAME;
-  return !eventName || eventName === "pull_request";
+function classifyIsolationPaths(files) {
+  return spawnSync("python3", ["scripts/check_app_terraform_isolation.py"], {
+    cwd: ROOT,
+    encoding: "utf8",
+    input: files.length > 0 ? `${files.join("\n")}\n` : "",
+  });
 }
 
-function runIsolationGate(baseRef) {
+function firstParentCommitDiffs(baseRef) {
+  const shas = gitLines(["rev-list", "--reverse", "--first-parent", `${baseRef}..HEAD`]);
+  return shas.map((sha) => ({
+    sha,
+    files: gitLines(["diff", "--name-only", "--diff-filter=ACMR", `${sha}^`, sha]),
+  }));
+}
+
+function runIsolationGate(baseRef, eventName) {
+  if (usesPerCommitIsolation(eventName)) {
+    const commits = firstParentCommitDiffs(baseRef);
+    return {
+      mode: "per-commit",
+      results: commits.map((commit) => ({
+        ...classifyIsolationPaths(commit.files),
+        sha: commit.sha,
+      })),
+    };
+  }
   // Diff from the merge base, not the moving base tip. A two-dot diff against
   // a branch that has advanced reports everything the base gained after the
   // branch point as if this change reverted it.
   const mergeBase = gitText(["merge-base", baseRef, "HEAD"]);
   const files = gitLines(["diff", "--name-only", "--diff-filter=ACMR", mergeBase, "HEAD"]);
-  const result = spawnSync("python3", ["scripts/check_app_terraform_isolation.py"], {
-    cwd: ROOT,
-    encoding: "utf8",
-    input: `${files.join("\n")}\n`,
-  });
-  return { ...result, mergeBase };
+  return {
+    mode: "range",
+    mergeBase,
+    results: [{ ...classifyIsolationPaths(files), sha: null }],
+  };
+}
+
+function recordIsolationFailures(isolation, failures) {
+  const startError = isolation.results.find((result) => result.error);
+  if (startError) {
+    failures.push(`G13: could not start: ${startError.error.message}`);
+  }
+  if (isolation.results.some((result) => !result.error && result.status !== 0)) {
+    failures.push("G13: do not mix deployable application files with terraform/");
+  }
+}
+
+function logIsolationGate(baseRef, isolation) {
+  if (isolation.mode === "per-commit") {
+    console.log(
+      `G13: application and Terraform isolation (merge_group, ${plural(isolation.results.length, "queued PR")} vs ${baseRef.slice(0, 7)})`,
+    );
+    for (const result of isolation.results) {
+      const output = `${result.stdout ?? ""}${result.stderr ?? ""}`.trim();
+      const prefix = result.sha ? result.sha.slice(0, 7) : "commit";
+      if (output) {
+        console.log(`  ${prefix}: ${output.replaceAll("\n", "\n    ")}`);
+      }
+    }
+    return;
+  }
+  const mergeBase = isolation.mergeBase ?? "unresolvable";
+  console.log(
+    `G13: application and Terraform isolation (${baseRef}...HEAD, merge base ${mergeBase.slice(0, 7)})`,
+  );
+  const result = isolation.results[0];
+  if (!result) return;
+  const output = `${result.stdout ?? ""}${result.stderr ?? ""}`.trim();
+  if (output) console.log(`  ${output.replaceAll("\n", "\n  ")}`);
 }
 
 function main() {
@@ -336,9 +392,10 @@ function main() {
   }
 
   console.log("─".repeat(64));
-  if (!shouldRunLiveIsolation()) {
+  const eventName = process.env.GITHUB_EVENT_NAME;
+  if (!shouldRunLiveIsolation(eventName)) {
     console.log(
-      `G13: skipped — live isolation is a pull-request property (event: ${process.env.GITHUB_EVENT_NAME})`,
+      `G13: skipped — live isolation runs on pull_request, merge_group, and local (event: ${eventName})`,
     );
   } else if (!baseRef) {
     console.log("G13: application and Terraform isolation (no base...HEAD)");
@@ -349,28 +406,16 @@ function main() {
   } else {
     let isolation;
     try {
-      isolation = runIsolationGate(baseRef);
+      isolation = runIsolationGate(baseRef, eventName);
     } catch (error) {
       console.log(`G13: application and Terraform isolation (${baseRef}...HEAD)`);
-      console.log("  FAIL (could not resolve merge base)");
+      console.log("  FAIL (could not resolve isolation diffs)");
       const message = error instanceof Error ? error.message : String(error);
-      failures.push(`G13: could not resolve merge base against HEAD: ${message}`);
+      failures.push(`G13: could not resolve isolation diffs against HEAD: ${message}`);
     }
     if (isolation) {
-      const mergeBase = isolation.mergeBase ?? "unresolvable";
-      console.log(
-        `G13: application and Terraform isolation (${baseRef}...HEAD, merge base ${mergeBase.slice(0, 7)})`,
-      );
-      if (isolation.error) {
-        console.log("  FAIL (could not start)");
-        failures.push(`G13: could not start: ${isolation.error.message}`);
-      } else {
-        const output = `${isolation.stdout ?? ""}${isolation.stderr ?? ""}`.trim();
-        if (output) console.log(`  ${output.replaceAll("\n", "\n  ")}`);
-        if (isolation.status !== 0) {
-          failures.push("G13: do not mix deployable application files with terraform/");
-        }
-      }
+      logIsolationGate(baseRef, isolation);
+      recordIsolationFailures(isolation, failures);
     }
   }
 
diff --git a/scripts/test-g13-live-isolation.mjs b/scripts/test-g13-live-isolation.mjs
new file mode 100644
index 00000000..5e402e4c
--- /dev/null
+++ b/scripts/test-g13-live-isolation.mjs
@@ -0,0 +1,73 @@
+import assert from "node:assert/strict";
+import { spawnSync } from "node:child_process";
+import path from "node:path";
+import { describe, it } from "node:test";
+import { fileURLToPath } from "node:url";
+
+import {
+  liveIsolationFileSets,
+  shouldRunLiveIsolation,
+  usesPerCommitIsolation,
+} from "./g13-live-isolation.mjs";
+
+const SCRIPT_DIR = path.dirname(fileURLToPath(import.meta.url));
+const CLASSIFIER = path.join(SCRIPT_DIR, "check_app_terraform_isolation.py");
+const TERRAFORM_ONLY = ["terraform/live/dev/main.tf"];
+const APP_ONLY = ["src/app/routes.tsx"];
+
+function classify(files) {
+  const result = spawnSync("python3", [CLASSIFIER, ...files], { encoding: "utf8" });
+  return result.status;
+}
+
+function anySetFails(fileSets) {
+  return fileSets.some((files) => classify(files) !== 0);
+}
+
+describe("shouldRunLiveIsolation", () => {
+  it("runs locally and on pull_request", () => {
+    assert.equal(shouldRunLiveIsolation(undefined), true);
+    assert.equal(shouldRunLiveIsolation(""), true);
+    assert.equal(shouldRunLiveIsolation("pull_request"), true);
+  });
+
+  it("runs on merge_group so the required check classifies the candidate", () => {
+    assert.equal(shouldRunLiveIsolation("merge_group"), true);
+    assert.equal(usesPerCommitIsolation("merge_group"), true);
+  });
+
+  it("skips push and other CI events", () => {
+    assert.equal(shouldRunLiveIsolation("push"), false);
+    assert.equal(shouldRunLiveIsolation("workflow_dispatch"), false);
+    assert.equal(usesPerCommitIsolation("pull_request"), false);
+  });
+});
+
+describe("liveIsolationFileSets", () => {
+  it("classifies the PR range as one change set", () => {
+    const range = [...TERRAFORM_ONLY, ...APP_ONLY];
+    const sets = liveIsolationFileSets("pull_request", range, [
+      { files: TERRAFORM_ONLY },
+      { files: APP_ONLY },
+    ]);
+    assert.deepEqual(sets, [range]);
+    assert.equal(anySetFails(sets), true);
+  });
+
+  it("classifies each queued PR, not the merge-group union", () => {
+    const union = [...TERRAFORM_ONLY, ...APP_ONLY];
+    const sets = liveIsolationFileSets("merge_group", union, [
+      { files: TERRAFORM_ONLY },
+      { files: APP_ONLY },
+    ]);
+    assert.deepEqual(sets, [TERRAFORM_ONLY, APP_ONLY]);
+    assert.equal(anySetFails(sets), false);
+    assert.equal(classify(union), 1);
+  });
+
+  it("fails a single queued PR that mixes terraform and app files", () => {
+    const mixed = [...TERRAFORM_ONLY, ...APP_ONLY];
+    const sets = liveIsolationFileSets("merge_group", mixed, [{ files: mixed }]);
+    assert.equal(anySetFails(sets), true);
+  });
+});
diff --git a/terraform/README.md b/terraform/README.md
index ddeb0bc5..40b78a09 100644
--- a/terraform/README.md
+++ b/terraform/README.md
@@ -57,7 +57,7 @@ bash scripts/test-verify-cloudfront-release.sh
 PRs cannot mix `terraform/` with deployable application files. Workflow, docs,
 and gate-script changes may travel with either side. G13 is
 `python3 scripts/check_app_terraform_isolation.py` against the merge base of
-the PR.
+the PR, and against each queued PR (first-parent commit) on `merge_group`.
 
 `npm run test:terraform` and `npm run verify` wrap the same gates. They never
 create an HCP run or touch AWS.