diff --git a/.github/scripts/artifact-workflow-filter.test.js b/.github/scripts/artifact-workflow-filter.test.js
new file mode 100644
index 00000000000..0214907fa24
--- /dev/null
+++ b/.github/scripts/artifact-workflow-filter.test.js
@@ -0,0 +1,58 @@
+'use strict';
+
+const fs = require('node:fs');
+const path = require('node:path');
+const assert = require('node:assert/strict');
+const { test } = require('node:test');
+
+function conditionFor(file, job) {
+    const source = fs.readFileSync(path.join(__dirname, '../workflows', file), 'utf8').replace(/\r\n/g, '\n');
+    const jobBody = source.split(`\n  ${job}:\n`)[1]?.split(/\n  [\w-]+:\n/)[0];
+    const expression = jobBody?.match(/\n    if: >\n((?:      .*\n)+)/)?.[1].trim();
+    assert.ok(expression, `Missing condition for ${file}:${job}`);
+    // The conditions use only member access, == and &&, so they run as JavaScript.
+    // GitHub's == ignores case and a missing object yields null; JS models neither.
+    return new Function('github', `return Boolean(${expression});`);
+}
+
+function event(overrides = {}) {
+    return {
+        workflow: { path: '.github/workflows/ci.yml' },
+        workflow_run: { name: 'Build firmware', event: 'pull_request', conclusion: 'success' },
+        ...overrides,
+    };
+}
+
+for (const [file, job] of [['pr-test-builds.yml', 'publish'], ['ci-size-report.yml', 'pr-comment']]) {
+    const accepts = conditionFor(file, job);
+    test(`${file}: accepts firmware without workflow_run.path`, () => {
+        assert.equal(accepts({ event: event() }), true);
+    });
+    test(`${file}: rejects same-name non-code workflow`, () => {
+        assert.equal(accepts({ event: event({ workflow: { path: '.github/workflows/non-code-change.yaml' } }) }), false);
+    });
+    test(`${file}: ignores a misleading run path`, () => {
+        const payload = event({ workflow: { path: '.github/workflows/non-code-change.yaml' } });
+        payload.workflow_run.path = '.github/workflows/ci.yml';
+        assert.equal(accepts({ event: payload }), false);
+    });
+    test(`${file}: rejects unsuccessful and non-PR runs`, () => {
+        for (const conclusion of ['failure', 'cancelled', 'skipped', 'action_required', null]) {
+            const payload = event();
+            payload.workflow_run.conclusion = conclusion;
+            assert.equal(accepts({ event: payload }), false);
+        }
+        const payload = event();
+        payload.workflow_run.event = 'push';
+        assert.equal(accepts({ event: payload }), false);
+    });
+    test(`${file}: rejects missing or unknown workflow paths`, () => {
+        for (const workflow of [{}, { path: '.github/workflows/other.yml' }]) {
+            assert.equal(accepts({ event: event({ workflow }) }), false);
+        }
+    });
+}
+
+test('firmware workflow path exists', () => {
+    assert.ok(fs.existsSync(path.join(__dirname, '../..', event().workflow.path)));
+});
diff --git a/.github/workflows/README.md b/.github/workflows/README.md
index 7e28f7cad01..8b469ad949c 100644
--- a/.github/workflows/README.md
+++ b/.github/workflows/README.md
@@ -121,6 +121,13 @@ as `pr-test-builds.yml`** (secrets available even for fork PRs).
 **Triggers:** Pull requests
 **Purpose:** Detects PRs with only documentation/formatting changes
 
+It shares the name `Build firmware` with `ci.yml` but produces none of its
+artifacts. The `workflow_run` consumers `pr-test-builds.yml` and
+`ci-size-report.yml` therefore also require
+`github.event.workflow.path == '.github/workflows/ci.yml'` (a path, not a
+workflow ID, so forks behave the same). Check both conditions with
+`node --test .github/scripts/artifact-workflow-filter.test.js`.
+
 ## Configuration Files
 
 - `../.github/stale.yml` - Stale issue/PR management
diff --git a/.github/workflows/ci-size-report.yml b/.github/workflows/ci-size-report.yml
index f095124a0b9..d5d6e7a3772 100644
--- a/.github/workflows/ci-size-report.yml
+++ b/.github/workflows/ci-size-report.yml
@@ -34,8 +34,9 @@ name: CI Size Report
 #    of the two fires per PR and either satisfies the same required-status-
 #    check name. `workflow_run` can't tell the two apart by name (see
 #    github-actions-workflows.md), and the stub's only job is `test` — no
-#    `upload-artifacts`, none of the artifacts this job needs — so a guard
-#    step checks for that job directly before downloading anything.
+#    `upload-artifacts`, none of the artifacts this job needs — so pr-comment
+#    filters on the workflow path, and a guard step still checks that
+#    `upload-artifacts` succeeded before downloading anything.
 #
 # Requires the same repository secret PR_BUILDS_TOKEN as pr-test-builds.yml
 # (Contents: write access to iNavFlight/pr-test-builds).
@@ -137,6 +138,7 @@ jobs:
     runs-on: ubuntu-latest
     if: >
       github.event.workflow_run.name == 'Build firmware' &&
+      github.event.workflow.path == '.github/workflows/ci.yml' &&
       github.event.workflow_run.event == 'pull_request' &&
       github.event.workflow_run.conclusion == 'success'
     concurrency:
@@ -154,12 +156,10 @@ jobs:
       # untrusted code is never checked out in this privileged context.
       - uses: actions/checkout@v4
 
-      # ci.yml's "Build firmware" name is shared with the non-code-change.yaml
-      # stub (see comment at the top of this file), whose only job is `test`
-      # — no upload-artifacts, none of the artifacts downloaded below. Check
-      # for that job directly rather than trusting the aggregate
-      # workflow_run.conclusion, which the job-level `if:` above already
-      # confirmed is 'success' for either workflow.
+      # The job-level `if:` already excludes the non-code-change.yaml stub by
+      # path (see comment at the top of this file). Still check
+      # upload-artifacts directly, so a renamed or skipped job skips the
+      # comment instead of failing on the downloads below.
       - name: Check upload-artifacts job succeeded
         id: check
         env:
diff --git a/.github/workflows/pr-test-builds.yml b/.github/workflows/pr-test-builds.yml
index 19867077aa5..8ead14bd46c 100644
--- a/.github/workflows/pr-test-builds.yml
+++ b/.github/workflows/pr-test-builds.yml
@@ -13,9 +13,11 @@ on:
 jobs:
   publish:
     runs-on: ubuntu-latest
-    # Only act on pull_request-triggered runs that succeeded.
+    # Only act on successful pull_request runs of ci.yml. non-code-change.yaml
+    # shares the name "Build firmware" but uploads no artifacts.
     if: >
       github.event.workflow_run.event == 'pull_request' &&
+      github.event.workflow.path == '.github/workflows/ci.yml' &&
       github.event.workflow_run.conclusion == 'success'
     # Prevent concurrent runs for the same PR branch racing on the
     # release delete/create cycle.