Use affected-test plans to narrow Loki visual tests (#82050)

2026-09-16 12:37:30 +12:00
parent 548573f22d
commit e677b6b267
21 changed files with 1028 additions and 185 deletions
--- a/.dependency-cruiser.cjs
+++ b/.dependency-cruiser.cjs
@@ -2,7 +2,7 @@
 // imported, vs the *allowed* edges in module-boundaries.mjs). Consumed by
 // .github/scripts/create-test-plan.ts.
 //
-//   bunx depcruise frontend/src enterprise/frontend/src \
+//   bunx depcruise frontend/src enterprise/frontend/src .storybook/preview.tsx \
 //     --config .dependency-cruiser.cjs --output-type json > dependency-graph.json

 /** @type {import('dependency-cruiser').IConfiguration} */
@@ -10,7 +10,7 @@ module.exports = {
  options: {
    // Keep only edges between our own source files (drops node_modules etc.),
    // which keeps the JSON small.
-    includeOnly: "^(frontend/src|enterprise/frontend/src)/",
+    includeOnly: "^(frontend/src|enterprise/frontend/src|\\.storybook)/",

    doNotFollow: { path: "node_modules" },

--- a/.github/actions/create-test-plan/action.yml
+++ b/.github/actions/create-test-plan/action.yml
@@ -99,6 +99,10 @@ runs:
          echo
          echo "Changed: $(jq '.stats.fe_files_changed' "$plan") FE / $(jq '.stats.be_files_changed' "$plan") BE file(s) · $(jq '.stats.fe_modules_affected_usage' "$plan") FE module(s) affected"
          echo
+          if [ "$(jq '.stats.loki_preview_touched' "$plan")" = "true" ]; then
+            echo "**Loki: full run**: a file the Storybook preview imports changed."
+            echo
+          fi
          e2e_run=$(jq '.stats.e2e_specs_to_run_usage' "$plan")
          e2e_all=$(jq '.stats.e2e_specs_all' "$plan")
          if [ "$e2e_run" -eq "$e2e_all" ]; then
--- a/.github/actions/prepare-test-selection/action.yml
+++ b/.github/actions/prepare-test-selection/action.yml
@@ -0,0 +1,39 @@
+name: Prepare test selection
+description: Download this run's test plan and write the suite's selected test paths.
+
+inputs:
+  suite:
+    description: The suite to select tests for (unit, loki or e2e).
+    required: true
+  test-plan-artifact-id:
+    description: ID of this run's test-plan.json artifact.
+    required: true
+  require-download:
+    description: Fail the step when the test plan download fails, instead of running the full suite.
+    required: false
+    default: "false"
+
+outputs:
+  paths-file:
+    description: JSON file listing the selected test paths, or '' when the suite runs in full.
+    value: ${{ steps.selection.outputs.paths-file }}
+  selection:
+    description: full, narrowed or empty, or '' when the plan is unavailable and the suite runs in full.
+    value: ${{ steps.selection.outputs.selection }}
+
+runs:
+  using: composite
+  steps:
+    - name: Download test plan
+      id: test-plan
+      continue-on-error: ${{ inputs.require-download != 'true' }}
+      uses: actions/download-artifact@v8
+      with:
+        artifact-ids: ${{ inputs.test-plan-artifact-id }}
+        path: ${{ runner.temp }}/test-plan
+    - name: Prepare test selection
+      id: selection
+      shell: bash
+      env:
+        PLAN_DOWNLOADED: ${{ steps.test-plan.outcome }}
+      run: bun .github/scripts/prepare-test-selection.ts "${{ inputs.suite }}"
--- a/.github/file-paths.yaml
+++ b/.github/file-paths.yaml
@@ -78,6 +78,7 @@ frontend_all: &frontend_all

 frontend_loki_ci: &frontend_loki_ci
  - ".github/workflows/loki.yml"
+  - "loki.config.js"
  - ".loki/**"
  - ".storybook/**"

@@ -96,6 +97,19 @@ frontend_loki_infra: &frontend_loki_infra
  - *frontend_configs
  - *shared_ci
  - *frontend_loki_ci
+  - "frontend/build/shared/**"
+  - "frontend/test/__support__/**"
+  - "patches/**"
+  # dependency-cruiser doesn't follow CSS @import, so global styles must run every story.
+  - "frontend/src/metabase/css/**/*.css"
+  # Storybook serves resources/frontend_client as static files, and the stories bundle the app's SVGs.
+  - "resources/frontend_client/**"
+  - "frontend/**/*.svg"
+  - "enterprise/frontend/**/*.svg"
+
+frontend_loki_all:
+  - *frontend_sources
+  - *frontend_loki_infra

 # Everything the ci-scripts jest project runs or depends on.
 # test-unit ignores that project, so this filter is the only thing that reruns it.
@@ -107,6 +121,8 @@ ci_scripts:
  - ".github/file-paths.yaml"
  - ".github/scripts/**"
  - ".github/actions/**"
+  - ".github/workflows/loki.yml"
+  - ".storybook/story-files.cjs"
  - "frontend/lint/module-boundaries.mjs"
  - "frontend/lint/shared-tiers.mjs"
  - "frontend/test/jest-test-paths-filter.ts"
--- a/.github/scripts/affected-modules.ts
+++ b/.github/scripts/affected-modules.ts
@@ -105,6 +105,28 @@ export function getAffectedFiles(
  return affected;
 }

+/** The file plus every file it transitively imports. */
+export function getTransitiveDependencies(
+  fileDependencies: FileDependency[],
+  file: string,
+): Set<string> {
+  const dependenciesOf = new Map(
+    fileDependencies.map(({ source, dependencies }) => [source, dependencies]),
+  );
+  const reached = new Set([file]);
+  const queue = [file];
+  while (queue.length > 0) {
+    const current = queue.shift()!;
+    for (const dependency of dependenciesOf.get(current) ?? []) {
+      if (!reached.has(dependency)) {
+        reached.add(dependency);
+        queue.push(dependency);
+      }
+    }
+  }
+  return reached;
+}
+
 export type ModuleGraph = {
  nodes: ModuleNode[];
  /**
--- a/.github/scripts/affected-modules.unit.spec.ts
+++ b/.github/scripts/affected-modules.unit.spec.ts
@@ -6,6 +6,7 @@ import {
  getAffectedFiles,
  getAffectedModules,
  getChangedModules,
+  getTransitiveDependencies,
  mapFileToModule,
  parseCruiseModules,
 } from "./affected-modules";
@@ -123,6 +124,31 @@ describe("affected modules", () => {
    });
  });

+  describe("getTransitiveDependencies", () => {
+    it("should return the file and everything it transitively imports", () => {
+      expect(
+        [...getTransitiveDependencies(FILE_DEPS, "src/app.js")].sort(),
+      ).toEqual(["src/app.js", "src/foo/foo.tsx", "src/utils/colors.ts"]);
+    });
+
+    it("should return only the file when it imports nothing", () => {
+      expect([
+        ...getTransitiveDependencies(FILE_DEPS, "src/utils/colors.ts"),
+      ]).toEqual(["src/utils/colors.ts"]);
+    });
+
+    it("should stop at an import cycle", () => {
+      const cyclic = [
+        { source: "src/a.ts", dependencies: ["src/b.ts"] },
+        { source: "src/b.ts", dependencies: ["src/a.ts"] },
+      ];
+
+      expect([...getTransitiveDependencies(cyclic, "src/a.ts")].sort()).toEqual(
+        ["src/a.ts", "src/b.ts"],
+      );
+    });
+  });
+
  describe("buildUsageModuleGraph + getAffectedModules", () => {
    const usageGraph = buildUsageModuleGraph(ELEMENTS, FILE_DEPS);

--- a/.github/scripts/affected-tests.ts
+++ b/.github/scripts/affected-tests.ts
@@ -11,6 +11,7 @@ import {
  buildUsageModuleGraph,
  getAffectedModules,
  getChangedModules,
+  getTransitiveDependencies,
  mapFileToModule,
 } from "./affected-modules";

@@ -21,6 +22,7 @@ export type TestPlanStats = {
  be_files_total: number;
  unit_infra_touched: boolean;
  loki_infra_touched: boolean;
+  loki_preview_touched: boolean;
  shared_sources_touched: boolean;
  fe_modules_total: number;
  fe_modules_changed: number;
@@ -52,6 +54,8 @@ export type CreateTestPlanInput = {
  // Null falls back to the rules graph.
  loadFileDependencies: () => FileDependency[] | null;
  testFilesBySuite: { unit: string[]; loki: string[]; e2e: string[] };
+  // Storybook's preview file, whose imports wrap every story.
+  lokiPreviewFile: string;
  e2eSpecFiles: Record<string, string[]> | null;
  unitInfraTouched: boolean;
  lokiInfraTouched: boolean;
@@ -134,6 +138,7 @@ export function createTestPlan({
  changedFiles,
  loadFileDependencies,
  testFilesBySuite,
+  lokiPreviewFile,
  e2eSpecFiles,
  unitInfraTouched,
  lokiInfraTouched,
@@ -158,7 +163,7 @@ export function createTestPlan({
  // cljc/cljs compile into the FE bundle, so they force a full run that module
  // selection can't narrow — same effect as a suite's own infra changing.
  const unitForceAll = unitInfraTouched || sharedSourcesTouched;
-  const lokiForceAll = lokiInfraTouched || sharedSourcesTouched;
+  const lokiInfraForceAll = lokiInfraTouched || sharedSourcesTouched;
  // e2e is integration-level, so anything the FE-coverage manifest can't see
  // forces a full run: cljc/cljs in the bundle (sharedSourcesTouched), a backend
  // change that can break the UI (beFilesChanged), an e2e harness/support change
@@ -171,12 +176,26 @@ export function createTestPlan({

  // The cruise takes seconds, so it is skipped when every suite runs in full anyway.
  const edges =
-    unitForceAll && lokiForceAll && e2eForceAll ? null : loadFileDependencies();
+    unitForceAll && lokiInfraForceAll && e2eForceAll
+      ? null
+      : loadFileDependencies();
  const usageGraph = edges
    ? buildUsageModuleGraph(elements, edges)
    : rulesGraph;
  const usageAffected = getAffectedModules(usageGraph, changedFiles);

+  // The preview wraps every story, so a change to a file it imports can change any screenshot.
+  const previewDependencies = edges
+    ? getTransitiveDependencies(edges, lokiPreviewFile)
+    : new Set<string>();
+  const lokiPreviewTouched = changedFiles.some((file) =>
+    previewDependencies.has(file),
+  );
+  // Without the cruise, the rules graph cannot account for the preview's
+  // global dependencies, so it cannot safely narrow Loki.
+  const lokiForceAll =
+    lokiInfraForceAll || lokiPreviewTouched || edges === null;
+
  const select = (forceAll: boolean, affected: Set<string>, files: string[]) =>
    forceAll ? files : filterAffectedTests(nodes, affected, files);

@@ -213,6 +232,7 @@ export function createTestPlan({
      be_files_total: beFilesTotal,
      unit_infra_touched: unitInfraTouched,
      loki_infra_touched: lokiInfraTouched,
+      loki_preview_touched: lokiPreviewTouched,
      shared_sources_touched: sharedSourcesTouched,
      fe_modules_total: totalModules,
      fe_modules_changed: changedModules.size,
--- a/.github/scripts/affected-tests.unit.spec.ts
+++ b/.github/scripts/affected-tests.unit.spec.ts
@@ -28,6 +28,7 @@ const baseInput = {
  rules: RULES,
  loadFileDependencies: () => null,
  testFilesBySuite: { unit: UNIT_FILES, loki: LOKI_FILES, e2e: E2E_FILES },
+  lokiPreviewFile: ".storybook/preview.tsx",
  e2eSpecFiles: null,
  unitInfraTouched: false,
  lokiInfraTouched: false,
@@ -41,7 +42,10 @@ const baseInput = {

 describe("createTestPlan", () => {
  it("runs only specs in affected modules (rules graph)", () => {
-    const plan = createTestPlan({ ...baseInput, changedFiles: ["src/foo/x.ts"] });
+    const plan = createTestPlan({
+      ...baseInput,
+      changedFiles: ["src/foo/x.ts"],
+    });

    expect(plan.stats.fe_modules_changed).toBe(1);
    expect(plan.stats.fe_modules_affected_rules).toBe(1);
@@ -50,8 +54,8 @@ describe("createTestPlan", () => {
      "src/foo/foo.unit.spec.ts",
    ]);
    expect(plan.stats.unit_specs_to_run_rules).toBe(2);
-    expect(plan.stats.loki_stories_to_run_rules).toBe(1);
-    // With no file deps, usage falls back to rules.
+    expect(plan.loki_stories_to_run).toEqual(LOKI_FILES);
+    // With no file deps, unit usage falls back to rules, but Loki runs in full.
    expect(plan.stats.unit_specs_to_run_usage).toBe(2);
  });

@@ -91,14 +95,69 @@ describe("createTestPlan", () => {
      ...baseInput,
      changedFiles: ["docs/readme.md"],
      unitInfraTouched: true,
+      loadFileDependencies: () => [],
    });

    expect(plan.stats.unit_specs_to_run_rules).toBe(UNIT_FILES.length);
    expect(plan.stats.loki_stories_to_run_rules).toBe(0);
  });

+  // The preview imports the theme, which imports the colors.
+  const PREVIEW_DEPS = [
+    { source: ".storybook/preview.tsx", dependencies: ["src/utils/theme.ts"] },
+    { source: "src/utils/theme.ts", dependencies: ["src/utils/colors.ts"] },
+    { source: "src/foo/foo.tsx", dependencies: ["src/foo/x.ts"] },
+  ];
+
+  it("forces a full Loki run when the Storybook preview imports a changed file", () => {
+    const plan = createTestPlan({
+      ...baseInput,
+      changedFiles: ["src/utils/colors.ts"],
+      loadFileDependencies: () => PREVIEW_DEPS,
+      e2eSpecFiles: { "e2e/test/scenarios/a.cy.spec.ts": ["src/bar/b.ts"] },
+    });
+
+    expect(plan.stats.loki_preview_touched).toBe(true);
+    expect(plan.stats.loki_stories_to_run_rules).toBe(LOKI_FILES.length);
+    expect(plan.loki_stories_to_run).toEqual(LOKI_FILES);
+    // Unit and e2e still narrow to what the usage graph reaches from the change.
+    expect(plan.fe_unit_specs_to_run).toEqual(["src/utils/utils.unit.spec.ts"]);
+    expect(plan.e2e_specs_to_run).toEqual([]);
+  });
+
+  it("narrows Loki when the Storybook preview does not import the changed file", () => {
+    const plan = createTestPlan({
+      ...baseInput,
+      changedFiles: ["src/foo/x.ts"],
+      loadFileDependencies: () => PREVIEW_DEPS,
+    });
+
+    expect(plan.stats.loki_preview_touched).toBe(false);
+    expect(plan.loki_stories_to_run).toEqual(["src/foo/Foo.stories.tsx"]);
+  });
+
+  it("runs all Loki stories when the cruise fails even if rules select fewer", () => {
+    const plan = createTestPlan({
+      ...baseInput,
+      changedFiles: ["src/foo/x.ts"],
+      loadFileDependencies: () => null,
+      e2eSpecFiles: { "e2e/test/scenarios/a.cy.spec.ts": ["src/bar/b.ts"] },
+    });
+
+    expect(plan.stats.loki_preview_touched).toBe(false);
+    expect(plan.loki_stories_to_run).toEqual(LOKI_FILES);
+    expect(plan.stats.loki_stories_to_run_rules).toBe(LOKI_FILES.length);
+    expect(plan.stats.loki_stories_to_run_usage).toBe(LOKI_FILES.length);
+    // Unit and E2E keep their rules-graph fallback.
+    expect(plan.fe_unit_specs_to_run).toEqual(UNIT_FILES.slice(0, 2));
+    expect(plan.e2e_specs_to_run).toEqual([]);
+  });
+
  it("runs the full e2e suite when no coverage manifest is available", () => {
-    const plan = createTestPlan({ ...baseInput, changedFiles: ["src/foo/x.ts"] });
+    const plan = createTestPlan({
+      ...baseInput,
+      changedFiles: ["src/foo/x.ts"],
+    });

    expect(plan.stats.e2e_specs_to_run_rules).toBe(E2E_FILES.length);
    expect(plan.stats.e2e_specs_to_run_usage).toBe(E2E_FILES.length);
--- a/.github/scripts/create-test-plan.ts
+++ b/.github/scripts/create-test-plan.ts
@@ -6,6 +6,7 @@ import { appendFileSync, existsSync, readFileSync } from "node:fs";

 import micromatch from "micromatch";

+import { MAIN_APP_STORY_GLOBS } from "../../.storybook/story-files.cjs";
 import { elements, rules } from "../../frontend/lint/module-boundaries.mjs";

 import { type FileDependency, parseCruiseModules } from "./affected-modules";
@@ -22,11 +23,9 @@ const UNIT_GLOBS = [
  "!**/*.leak.unit.spec.{js,jsx,ts,tsx}", // run only by jest.memory.conf.js
 ];

-const STORY_ROOTS = ["frontend", "enterprise/frontend"];
-const STORY_GLOBS = [
-  "frontend/**/*.stories.{js,jsx,ts,tsx}",
-  "enterprise/frontend/**/*.stories.{js,jsx,ts,tsx}",
-];
+const FRONTEND_ROOTS = ["frontend", "enterprise/frontend"];
+
+const LOKI_PREVIEW_FILE = ".storybook/preview.tsx";

 // `git ls-files -- frontend enterprise/frontend` already prints just over a
 // megabyte of paths, and node's default maxBuffer is exactly 1 MiB: past that
@@ -52,7 +51,7 @@ const csvToList = (csv: string | undefined) =>
    .map((s) => s.trim())
    .filter(Boolean);

-// Runs dependency-cruiser over the frontend sources and parses its edges.
+// Runs dependency-cruiser over the frontend sources and the Storybook preview and parses its edges.
 // Null falls back to the rules graph, so a failed cruise never breaks the plan.
 function loadFileDependencies(): FileDependency[] | null {
  const output = "dependency-graph.json";
@@ -65,6 +64,7 @@ function loadFileDependencies(): FileDependency[] | null {
        "depcruise",
        "frontend/src",
        "enterprise/frontend/src",
+        LOKI_PREVIEW_FILE,
        "--config",
        ".dependency-cruiser.cjs",
        "--output-type",
@@ -120,9 +120,10 @@ const testPlan = createTestPlan({
  loadFileDependencies,
  testFilesBySuite: {
    unit: listFiles(UNIT_ROOTS, UNIT_GLOBS),
-    loki: listFiles(STORY_ROOTS, STORY_GLOBS),
+    loki: listFiles(FRONTEND_ROOTS, MAIN_APP_STORY_GLOBS),
    e2e: listSpecFiles(),
  },
+  lokiPreviewFile: LOKI_PREVIEW_FILE,
  e2eSpecFiles: readE2eSpecFiles(),
  unitInfraTouched: process.env.UNIT_INFRA_TOUCHED === "true",
  lokiInfraTouched: process.env.LOKI_INFRA_TOUCHED === "true",
@@ -130,7 +131,7 @@ const testPlan = createTestPlan({
  sharedSourcesTouched: process.env.SHARED_SOURCES_TOUCHED === "true",
  feFilesChanged: csvToList(process.env.FE_CHANGED_FILES).length,
  beFilesChanged: csvToList(process.env.BE_CHANGED_FILES).length,
-  feFilesTotal: listFiles(["frontend", "enterprise/frontend"], ["**"]).length,
+  feFilesTotal: listFiles(FRONTEND_ROOTS, ["**"]).length,
  beFilesTotal: listFiles(["src", "enterprise/backend"], ["**"]).length,
 });

--- a/.github/scripts/file-paths.unit.spec.ts
+++ b/.github/scripts/file-paths.unit.spec.ts
@@ -49,9 +49,9 @@ describe("file-paths.yaml", () => {
    "%s skips a ratchets-only change and still follows the rest of .clj-kondo",
    (name) => {
      expect(matches(name, ".clj-kondo/ratchets.edn")).toBe(false);
-      expect(
-        matches(name, ".clj-kondo/config/modules/ratchets.edn"),
-      ).toBe(false);
+      expect(matches(name, ".clj-kondo/config/modules/ratchets.edn")).toBe(
+        false,
+      );
      expect(matches(name, ".clj-kondo/config.edn")).toBe(true);
      expect(matches(name, ".clj-kondo/config/modules/config.edn")).toBe(true);
    },
@@ -80,12 +80,15 @@ describe("file-paths.yaml", () => {
    ).toBe(true);
  });

-  it.each(["jest.config.js", "jest.base.conf.js", "jest.esm-packages.js"])(
-    "runs CI script tests when %s changes",
-    (path) => {
-      expect(matches("ci_scripts", path)).toBe(true);
-    },
-  );
+  it.each([
+    "jest.config.js",
+    "jest.base.conf.js",
+    "jest.esm-packages.js",
+    ".storybook/story-files.cjs",
+    ".github/workflows/loki.yml",
+  ])("runs CI script tests when %s changes", (path) => {
+    expect(matches("ci_scripts", path)).toBe(true);
+  });

  it("runs the ratchet check on the ratchets file", () => {
    expect(matches("project_ratchet_checks", ".clj-kondo/ratchets.edn")).toBe(
@@ -98,4 +101,42 @@ describe("file-paths.yaml", () => {
      ),
    ).toBe(true);
  });
+
+  it.each([
+    "loki.config.js",
+    ".storybook/story-files.cjs",
+    ".storybook/preview.tsx",
+    ".loki/reference/chrome.laptop-Button.png",
+    ".github/workflows/loki.yml",
+    ".github/workflows/run-tests.yml",
+    ".github/actions/prepare-frontend/action.yml",
+    "frontend/build/shared/rspack/css-config.js",
+    "frontend/test/__support__/custom-viz-fixtures/calendar-heatmap/index.js",
+    "patches/@loki+browser+0.35.0.patch",
+    "frontend/src/metabase/css/index.module.css",
+    "frontend/src/metabase/css/core/base.module.css",
+    "resources/frontend_client/app/fonts/Lato/lato-v16-latin-regular.woff2",
+    "resources/frontend_client/app/assets/img/no_results.svg",
+    "frontend/src/metabase/ui/components/icons/Icon/icons/warning.svg",
+    "enterprise/frontend/src/metabase-enterprise/google_drive/database-error.svg",
+  ])("runs all Loki stories when %s changes", (file) => {
+    expect(matches("frontend_loki_all", file)).toBe(true);
+    expect(matches("frontend_loki_infra", file)).toBe(true);
+  });
+
+  it.each([
+    "frontend/src/metabase/ui/Button.stories.tsx",
+    "frontend/src/metabase/ui/components/feedback/Alert/Alert.module.css",
+    "frontend/build/embedding-sdk/rspack.config.js",
+  ])("allows a change to %s to narrow the Loki run", (file) => {
+    expect(matches("frontend_loki_all", file)).toBe(true);
+    expect(matches("frontend_loki_infra", file)).toBe(false);
+  });
+
+  it.each([
+    ".github/workflows/frontend.yml",
+    "frontend/test/metabase/scenarios/Button.unit.spec.tsx",
+  ])("does not run Loki stories when %s changes", (file) => {
+    expect(matches("frontend_loki_all", file)).toBe(false);
+  });
 });
--- a/.github/scripts/frontend-test-plan.unit.spec.ts
+++ b/.github/scripts/frontend-test-plan.unit.spec.ts
@@ -16,7 +16,7 @@ import {
  findEmptySelection,
  findRunnerFailure,
 } from "./check-unit-test-results";
-import { prepareUnitTestSelection } from "./prepare-unit-test-selection";
+import { prepareTestSelection } from "./prepare-test-selection";

 type Step = { name: string; run?: string; "continue-on-error"?: boolean };
 // js-yaml returns an untyped value, and this repository workflow defines the job's steps.
@@ -69,79 +69,6 @@ describe("frontend test plan handoff", () => {
    writeFileSync(join(dir, "test-plan/test-plan.json"), JSON.stringify(value));
  }

-  it.each([{ files: ["one.spec.cjs"] }, { files: [] }])(
-    "preserves an explicit selection: $files",
-    ({ files }) => {
-      writePlan(plan(files));
-      prepareUnitTestSelection(env);
-      expect(readFileSync(join(dir, "output"), "utf8")).toContain(
-        "paths-file=",
-      );
-      expect(
-        JSON.parse(readFileSync(join(dir, "unit-specs.json"), "utf8")),
-      ).toEqual(files);
-    },
-  );
-
-  it("writes the selection when invoked through Bun in CI", () => {
-    writePlan(plan(["one.spec.cjs"]));
-    const result = spawnSync(
-      "bun",
-      [resolve(__dirname, "prepare-unit-test-selection.ts")],
-      { env, encoding: "utf8" },
-    );
-    expect(result.status === 0 ? "" : result.stderr).toBe("");
-    expect(result.status).toBe(0);
-    expect(readFileSync(join(dir, "output"), "utf8")).toBe(
-      `paths-file=${join(dir, "unit-specs.json")}\n`,
-    );
-    expect(
-      JSON.parse(readFileSync(join(dir, "unit-specs.json"), "utf8")),
-    ).toEqual(["one.spec.cjs"]);
-  });
-
-  it("bypasses the filter for a full selection", () => {
-    writePlan(plan(["one.spec.cjs", "two.spec.cjs"]));
-    prepareUnitTestSelection(env);
-    expect(readFileSync(join(dir, "output"), "utf8")).toBe("");
-  });
-
-  it.each([
-    null,
-    {},
-    { ...plan([]), fe_unit_specs_to_run: "[]" },
-    { ...plan([]), fe_unit_specs_to_run: [null] },
-    { ...plan([]), fe_unit_specs_to_run: ["one.spec.cjs"] },
-    plan(["one.spec.cjs"], 0),
-  ])("runs in full for an invalid plan: %j", (value) => {
-    writePlan(value);
-    prepareUnitTestSelection(env);
-    expect(console.warn).toHaveBeenCalledWith(
-      expect.stringContaining("::warning::"),
-    );
-    expect(readFileSync(join(dir, "output"), "utf8")).toBe("");
-  });
-
-  it.each(["missing", "truncated", "download failed"])(
-    "runs in full when the artifact is %s",
-    (scenario) => {
-      if (scenario === "truncated") {
-        writeFileSync(
-          join(dir, "test-plan/test-plan.json"),
-          '{"fe_unit_specs_to_run":[',
-        );
-      } else if (scenario === "download failed") {
-        writePlan(plan([])); // Even a partial download must not be trusted.
-        env.PLAN_DOWNLOADED = "failure";
-      }
-      prepareUnitTestSelection(env);
-      expect(console.warn).toHaveBeenCalledWith(
-        expect.stringContaining("::warning::"),
-      );
-      expect(readFileSync(join(dir, "output"), "utf8")).toBe("");
-    },
-  );
-
  function jestCommand(useFilter: boolean) {
    return [
      process.execPath,
@@ -251,7 +178,7 @@ describe("frontend test plan handoff", () => {
    "loads the TypeScript filter natively with an empty selection: %s",
    (empty) => {
      writePlan(plan(empty ? [] : [join(dir, "pass.spec.cjs")]));
-      prepareUnitTestSelection(env);
+      prepareTestSelection("unit", env);
      env.JEST_TEST_PATHS_FILE = join(dir, "unit-specs.json");
      const result = runJest(
        {
--- a/.github/scripts/prepare-test-selection.ts
+++ b/.github/scripts/prepare-test-selection.ts
@@ -0,0 +1,122 @@
+import { appendFileSync, readFileSync, writeFileSync } from "node:fs";
+import { join } from "node:path";
+
+import type { TestPlan, TestPlanStats } from "./affected-tests";
+
+type NumberStat = {
+  [K in keyof TestPlanStats]: TestPlanStats[K] extends number ? K : never;
+}[keyof TestPlanStats];
+
+type Suite = {
+  name: string;
+  filesKey: Exclude<keyof TestPlan, "stats">;
+  totalKey: NumberStat;
+  selectedKey: NumberStat;
+  pathsFile: string;
+};
+
+export const SUITES = {
+  unit: {
+    name: "unit",
+    filesKey: "fe_unit_specs_to_run",
+    totalKey: "unit_specs_all",
+    selectedKey: "unit_specs_to_run_usage",
+    pathsFile: "unit-specs.json",
+  },
+  loki: {
+    name: "Loki",
+    filesKey: "loki_stories_to_run",
+    totalKey: "loki_stories_all",
+    selectedKey: "loki_stories_to_run_usage",
+    pathsFile: "loki-stories.json",
+  },
+  e2e: {
+    name: "E2E",
+    filesKey: "e2e_specs_to_run",
+    totalKey: "e2e_specs_all",
+    selectedKey: "e2e_specs_to_run_usage",
+    pathsFile: "e2e-specs.json",
+  },
+} satisfies Record<string, Suite>;
+
+function isSuiteName(name: string): name is keyof typeof SUITES {
+  return Object.hasOwn(SUITES, name);
+}
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return typeof value === "object" && value !== null;
+}
+
+function isStringArray(value: unknown): value is string[] {
+  return (
+    Array.isArray(value) && value.every((item) => typeof item === "string")
+  );
+}
+
+function isCount(value: unknown): value is number {
+  return typeof value === "number" && Number.isInteger(value) && value >= 0;
+}
+
+// null means a full run, and [] is an explicit selection of no tests.
+function readSelection(planFile: string, suite: Suite): string[] | null {
+  const plan: unknown = JSON.parse(readFileSync(planFile, "utf8"));
+  const files = isRecord(plan) ? plan[suite.filesKey] : undefined;
+  const stats = isRecord(plan) && isRecord(plan.stats) ? plan.stats : {};
+  const total = stats[suite.totalKey];
+  if (
+    !isStringArray(files) ||
+    files.some((file) => file.length === 0) ||
+    !isCount(total) ||
+    files.length !== stats[suite.selectedKey] ||
+    files.length > total
+  ) {
+    throw new Error(`Invalid ${suite.name} test selection`);
+  }
+  return files.length === total ? null : files;
+}
+
+export function prepareTestSelection(
+  suiteName: keyof typeof SUITES,
+  env: NodeJS.ProcessEnv = process.env,
+) {
+  const suite: Suite = SUITES[suiteName];
+  const { RUNNER_TEMP, GITHUB_OUTPUT, PLAN_DOWNLOADED } = env;
+  if (!RUNNER_TEMP || !GITHUB_OUTPUT) {
+    throw new Error("RUNNER_TEMP and GITHUB_OUTPUT are required");
+  }
+
+  let files: string[] | null;
+  try {
+    if (PLAN_DOWNLOADED !== "success") {
+      throw new Error("Test plan download failed");
+    }
+    files = readSelection(join(RUNNER_TEMP, "test-plan/test-plan.json"), suite);
+  } catch (error) {
+    console.warn(
+      `::warning::Test plan unavailable or invalid, running the full ${suite.name} suite: ${error}`,
+    );
+    return;
+  }
+
+  if (files === null) {
+    appendFileSync(GITHUB_OUTPUT, "selection=full\n");
+    return;
+  }
+
+  const pathsFile = join(RUNNER_TEMP, suite.pathsFile);
+  writeFileSync(pathsFile, JSON.stringify(files));
+  appendFileSync(
+    GITHUB_OUTPUT,
+    `paths-file=${pathsFile}\nselection=${files.length === 0 ? "empty" : "narrowed"}\n`,
+  );
+}
+
+if (require.main === module) {
+  const suiteName = process.argv[2] ?? "";
+  if (!isSuiteName(suiteName)) {
+    throw new Error(
+      `Unknown test suite "${suiteName}", expected one of: ${Object.keys(SUITES).join(", ")}`,
+    );
+  }
+  prepareTestSelection(suiteName);
+}
--- a/.github/scripts/prepare-test-selection.unit.spec.ts
+++ b/.github/scripts/prepare-test-selection.unit.spec.ts
@@ -0,0 +1,268 @@
+import { spawnSync } from "node:child_process";
+import {
+  mkdirSync,
+  mkdtempSync,
+  readFileSync,
+  rmSync,
+  writeFileSync,
+} from "node:fs";
+import { tmpdir } from "node:os";
+import { join, resolve } from "node:path";
+
+import { load } from "js-yaml";
+
+import { SUITES, prepareTestSelection } from "./prepare-test-selection";
+
+type Suite = (typeof SUITES)[keyof typeof SUITES];
+
+type Step = {
+  id?: string;
+  if?: string;
+  uses?: string;
+  run?: string;
+  env?: Record<string, string>;
+  with?: Record<string, string | boolean>;
+};
+
+const SCRIPT = resolve(__dirname, "prepare-test-selection.ts");
+const SUITE_NAMES = ["unit", "loki", "e2e"] satisfies (keyof typeof SUITES)[];
+
+function loadWorkflow(file: string) {
+  // js-yaml returns an untyped value, and these repository workflows define jobs with steps.
+  return load(
+    readFileSync(resolve(__dirname, "../workflows", file), "utf8"),
+  ) as {
+    jobs: Record<
+      string,
+      { if?: string; outputs?: Record<string, string>; steps?: Step[] }
+    >;
+  };
+}
+
+function loadAction() {
+  // js-yaml returns an untyped value, and this repository action defines outputs and steps.
+  return load(
+    readFileSync(
+      resolve(__dirname, "../actions/prepare-test-selection/action.yml"),
+      "utf8",
+    ),
+  ) as {
+    outputs: Record<string, { value: string }>;
+    runs: { steps: Step[] };
+  };
+}
+
+describe("prepareTestSelection", () => {
+  const { loki } = SUITES;
+  let dir: string;
+  let env: NodeJS.ProcessEnv;
+
+  beforeEach(() => {
+    jest.spyOn(console, "warn").mockImplementation(() => {});
+    dir = mkdtempSync(join(tmpdir(), "test-selection-"));
+    mkdirSync(join(dir, "test-plan"));
+    writeFileSync(join(dir, "output"), "");
+    env = {
+      ...process.env,
+      RUNNER_TEMP: dir,
+      GITHUB_OUTPUT: join(dir, "output"),
+      PLAN_DOWNLOADED: "success",
+    };
+  });
+
+  afterEach(() => {
+    jest.restoreAllMocks();
+    rmSync(dir, { recursive: true, force: true });
+  });
+
+  function plan(files: unknown, total = 2, suite: Suite = loki) {
+    return {
+      [suite.filesKey]: files,
+      stats: {
+        [suite.totalKey]: total,
+        [suite.selectedKey]: Array.isArray(files) ? files.length : 0,
+      },
+    };
+  }
+
+  function writePlan(value: unknown) {
+    writeFileSync(join(dir, "test-plan/test-plan.json"), JSON.stringify(value));
+  }
+
+  const output = () => readFileSync(join(dir, "output"), "utf8");
+
+  it.each([{ files: ["one.spec.cjs"] }, { files: [] }])(
+    "preserves an explicit selection: $files",
+    ({ files }) => {
+      writePlan(plan(files));
+      prepareTestSelection("loki", env);
+      expect(output()).toBe(
+        `paths-file=${join(dir, loki.pathsFile)}\nselection=${files.length > 0 ? "narrowed" : "empty"}\n`,
+      );
+      expect(
+        JSON.parse(readFileSync(join(dir, loki.pathsFile), "utf8")),
+      ).toEqual(files);
+    },
+  );
+
+  it("writes the selection when invoked through Bun in CI", () => {
+    writePlan(plan(["one.spec.cjs"]));
+    const result = spawnSync("bun", [SCRIPT, "loki"], {
+      env,
+      encoding: "utf8",
+    });
+    expect(result.status === 0 ? "" : result.stderr).toBe("");
+    expect(result.status).toBe(0);
+    expect(output()).toBe(
+      `paths-file=${join(dir, loki.pathsFile)}\nselection=narrowed\n`,
+    );
+  });
+
+  it("writes no paths file for a full selection", () => {
+    writePlan(plan(["one.spec.cjs", "two.spec.cjs"]));
+    prepareTestSelection("loki", env);
+    expect(output()).toBe("selection=full\n");
+  });
+
+  it.each([
+    null,
+    {},
+    plan("[]"),
+    plan([null]),
+    { ...plan([]), [loki.filesKey]: ["one.spec.cjs"] },
+    plan([""]),
+    plan(["one.spec.cjs"], 0),
+  ])("runs in full for an invalid plan: %j", (value) => {
+    writePlan(value);
+    prepareTestSelection("loki", env);
+    expect(console.warn).toHaveBeenCalledWith(
+      expect.stringContaining("::warning::"),
+    );
+    expect(output()).toBe("");
+  });
+
+  it.each([
+    { scenario: "the test plan is missing", setup: () => {} },
+    {
+      scenario: "the test plan is truncated",
+      setup: () => {
+        writeFileSync(
+          join(dir, "test-plan/test-plan.json"),
+          `{"${loki.filesKey}":[`,
+        );
+      },
+    },
+    {
+      scenario: "the download failed",
+      setup: () => {
+        writePlan(plan([])); // Even a partial download must not be trusted.
+        env.PLAN_DOWNLOADED = "failure";
+      },
+    },
+  ])("runs in full when $scenario", ({ setup }) => {
+    setup();
+    prepareTestSelection("loki", env);
+    expect(console.warn).toHaveBeenCalledWith(
+      expect.stringContaining("::warning::"),
+    );
+    expect(output()).toBe("");
+  });
+
+  it.each(SUITE_NAMES)(
+    "reads the %s selection from its own plan keys",
+    (suiteName) => {
+      const suite = SUITES[suiteName];
+      writePlan(plan(["one.spec.cjs"], 2, suite));
+      prepareTestSelection(suiteName, env);
+      expect(output()).toBe(
+        `paths-file=${join(dir, suite.pathsFile)}\nselection=narrowed\n`,
+      );
+      expect(
+        JSON.parse(readFileSync(join(dir, suite.pathsFile), "utf8")),
+      ).toEqual(["one.spec.cjs"]);
+    },
+  );
+
+  it("ignores the other suites' selections", () => {
+    writePlan({
+      ...plan(["one.spec.cjs", "two.spec.cjs"]),
+      [SUITES.unit.filesKey]: [],
+      [SUITES.e2e.filesKey]: [],
+    });
+    prepareTestSelection("loki", env);
+    expect(console.warn).not.toHaveBeenCalled();
+    expect(output()).toBe("selection=full\n");
+  });
+
+  it("rejects an unknown suite", () => {
+    const result = spawnSync("bun", [SCRIPT, "toString"], {
+      env,
+      encoding: "utf8",
+    });
+    expect(result.status).not.toBe(0);
+    expect(result.stderr).toContain('Unknown test suite "toString"');
+  });
+});
+
+describe("test selection workflow steps", () => {
+  const ACTION = "./.github/actions/prepare-test-selection";
+  const CONSUMERS: Record<string, { suite: keyof typeof SUITES }> = {
+    "frontend.yml": { suite: "unit" },
+    "loki.yml": { suite: "loki" },
+  };
+
+  it("skips Loki visual tests only for an empty story selection", () => {
+    const { jobs } = loadWorkflow("loki.yml");
+    expect(jobs["story-selection"].outputs?.selection).toBe(
+      "${{ steps.loki-selection.outputs.selection }}",
+    );
+    expect(jobs["visual-test"].if).toContain(
+      "needs.story-selection.outputs.selection != 'empty'",
+    );
+    expect(jobs["visual-test"].if).not.toMatch(/outputs\.[\w-]+ *[!=]= *'\d+'/);
+  });
+
+  it.each(Object.entries(CONSUMERS))(
+    "selects tests through the composite action in %s",
+    (file, { suite, ...inputs }) => {
+      const steps = Object.values(loadWorkflow(file).jobs).flatMap(
+        ({ steps = [] }) => steps.filter((step) => step.uses === ACTION),
+      );
+
+      expect(steps.length).toBeGreaterThan(0);
+      for (const step of steps) {
+        expect(step.with).toEqual({
+          suite,
+          "test-plan-artifact-id": expect.stringMatching(/^\$\{\{ .+ \}\}$/),
+          ...inputs,
+        });
+      }
+    },
+  );
+
+  it("downloads the test plan before preparing the selection", () => {
+    const { outputs, runs } = loadAction();
+    const [download, prepare] = runs.steps;
+
+    expect(download).toMatchObject({
+      uses: expect.stringMatching(/^actions\/download-artifact@/),
+      "continue-on-error": "${{ inputs.require-download != 'true' }}",
+      with: {
+        "artifact-ids": "${{ inputs.test-plan-artifact-id }}",
+        path: "${{ runner.temp }}/test-plan",
+      },
+    });
+    expect(prepare).toMatchObject({
+      env: { PLAN_DOWNLOADED: `\${{ steps.${download.id}.outcome }}` },
+      run: expect.stringContaining(
+        'prepare-test-selection.ts "${{ inputs.suite }}"',
+      ),
+    });
+    expect(outputs).toMatchObject({
+      "paths-file": {
+        value: `\${{ steps.${prepare.id}.outputs.paths-file }}`,
+      },
+      selection: { value: `\${{ steps.${prepare.id}.outputs.selection }}` },
+    });
+  });
+});
--- a/.github/scripts/prepare-unit-test-selection.ts
+++ b/.github/scripts/prepare-unit-test-selection.ts
@@ -1,53 +0,0 @@
-import { appendFileSync, readFileSync, writeFileSync } from "node:fs";
-import { join } from "node:path";
-
-// null means a full run, and [] is an explicit selection of no tests.
-function readSelection(planFile: string): string[] | null {
-  const { fe_unit_specs_to_run: files, stats } = JSON.parse(
-    readFileSync(planFile, "utf8"),
-  );
-  if (
-    !Array.isArray(files) ||
-    !files.every((file) => typeof file === "string" && file.length > 0) ||
-    !Number.isInteger(stats?.unit_specs_all) ||
-    stats.unit_specs_all < 0 ||
-    files.length !== stats.unit_specs_to_run_usage ||
-    files.length > stats.unit_specs_all
-  ) {
-    throw new Error("Invalid unit test selection");
-  }
-  return files.length === stats.unit_specs_all ? null : files;
-}
-
-export function prepareUnitTestSelection(env: NodeJS.ProcessEnv = process.env) {
-  const { RUNNER_TEMP, GITHUB_OUTPUT, PLAN_DOWNLOADED } = env;
-  if (!RUNNER_TEMP || !GITHUB_OUTPUT) {
-    throw new Error("RUNNER_TEMP and GITHUB_OUTPUT are required");
-  }
-
-  let files: string[] | null;
-  try {
-    if (PLAN_DOWNLOADED !== "success") {
-      throw new Error("Test plan download failed");
-    }
-    files = readSelection(join(RUNNER_TEMP, "test-plan/test-plan.json"));
-  } catch {
-    console.warn(
-      "::warning::Test plan unavailable or invalid; running the full unit suite.",
-    );
-    return;
-  }
-
-  // Full selections use Jest's normal discovery, without the filter.
-  if (files === null) {
-    return;
-  }
-
-  const pathsFile = join(RUNNER_TEMP, "unit-specs.json");
-  writeFileSync(pathsFile, JSON.stringify(files));
-  appendFileSync(GITHUB_OUTPUT, `paths-file=${pathsFile}\n`);
-}
-
-if (require.main === module) {
-  prepareUnitTestSelection();
-}
--- a/.github/scripts/story-files.unit.spec.ts
+++ b/.github/scripts/story-files.unit.spec.ts
@@ -0,0 +1,226 @@
+import { execFileSync } from "node:child_process";
+import { mkdtempSync, readFileSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join, resolve } from "node:path";
+
+import micromatch, { isMatch } from "micromatch";
+import { normalizeStories } from "storybook/internal/common";
+
+import {
+  MAIN_APP_STORY_GLOBS,
+  getStories,
+  hasExplicitTitle,
+} from "../../.storybook/story-files.cjs";
+
+const ROOT = resolve(__dirname, "../..");
+
+const tracked = execFileSync(
+  "git",
+  ["ls-files", "-z", "--", "frontend", "enterprise/frontend"],
+  { cwd: ROOT, encoding: "utf8", maxBuffer: 64 * 1024 * 1024 },
+)
+  .split("\0")
+  .filter(Boolean);
+const planned = micromatch(tracked, MAIN_APP_STORY_GLOBS, { dot: true }).sort();
+
+describe("getStories", () => {
+  let tempDir: string;
+  let pathsFile: string;
+
+  beforeEach(() => {
+    tempDir = mkdtempSync(join(tmpdir(), "story-files-"));
+    pathsFile = join(tempDir, "stories.json");
+  });
+
+  afterEach(() => {
+    rmSync(tempDir, { recursive: true, force: true });
+  });
+
+  it("loads the main app stories and docs when there is no plan", () => {
+    const patterns = getStories({ pathsFile: "", filter: "" });
+
+    expect(
+      isMatch("../frontend/src/metabase/ui/Button.stories.tsx", patterns),
+    ).toBe(true);
+    expect(isMatch("../frontend/src/metabase/ui/Button.mdx", patterns)).toBe(
+      true,
+    );
+    expect(
+      isMatch(
+        "../frontend/src/embedding-sdk-shared/Button.stories.tsx",
+        patterns,
+      ),
+    ).toBe(false);
+  });
+
+  it("builds only the files in the JSON plan", () => {
+    const files = planned.slice(0, 2);
+    writeFileSync(pathsFile, JSON.stringify(files));
+
+    expect(getStories({ pathsFile })).toEqual(
+      files.map((file) => `../${file}`),
+    );
+  });
+
+  it("builds a planned story with an explicit title", () => {
+    const story = join(tempDir, "Titled.stories.tsx");
+    writeFileSync(
+      story,
+      'const meta = { title: "Components/Titled" };\nexport default meta;\n',
+    );
+    writeFileSync(pathsFile, JSON.stringify([story]));
+
+    expect(getStories({ pathsFile })).toEqual([`../${story}`]);
+  });
+
+  it("rejects a planned story without an explicit title", () => {
+    const story = join(tempDir, "Untitled.stories.tsx");
+    writeFileSync(story, "export default { component: Untitled };\n");
+    writeFileSync(pathsFile, JSON.stringify([story]));
+
+    expect(() => getStories({ pathsFile })).toThrow(story);
+  });
+
+  it("rejects an untitled Alert story even though its args have a title", () => {
+    const source = readFileSync(
+      join(
+        ROOT,
+        "frontend/src/metabase/ui/components/feedback/Alert/Alert.stories.tsx",
+      ),
+      "utf8",
+    ).replace('  title: "Components/Feedback/Alert",\n', "");
+    const story = join(tempDir, "Alert.stories.tsx");
+    writeFileSync(story, source);
+    writeFileSync(pathsFile, JSON.stringify([story]));
+
+    expect(() => getStories({ pathsFile })).toThrow(story);
+  });
+
+  it("rejects an empty plan even when the CSV filter is set", () => {
+    writeFileSync(pathsFile, "[]");
+
+    expect(() =>
+      getStories({ pathsFile, filter: "frontend/src/Unselected.stories.tsx" }),
+    ).toThrow("No stories selected");
+  });
+
+  it("preserves the stress test's CSV filter", () => {
+    expect(
+      getStories({
+        filter: "frontend/One.stories.tsx,frontend/Two.stories.tsx",
+      }),
+    ).toEqual(["../frontend/One.stories.tsx", "../frontend/Two.stories.tsx"]);
+  });
+
+  it.each(["{", "null", '""', "{}", "[null]"])(
+    "rejects an invalid plan: %s",
+    (contents) => {
+      writeFileSync(pathsFile, contents);
+
+      expect(() => getStories({ pathsFile })).toThrow();
+    },
+  );
+});
+
+describe("hasExplicitTitle", () => {
+  it.each([
+    {
+      form: "double quotes",
+      source: 'export default {\n  title: "Components/Button",\n};\n',
+    },
+    {
+      form: "single quotes",
+      source: "export default {\n  title: 'Components/Button',\n};\n",
+    },
+    {
+      form: "a title constant",
+      source: 'const title = "Components/Button"; export default { title };',
+    },
+    {
+      form: "a meta constant",
+      source:
+        'const meta: Meta<typeof Button> = {\n  title: "Components/Button",\n};\n\nexport default meta;\n',
+    },
+    {
+      form: "a satisfies expression",
+      source:
+        'const meta = { title: "Components/Button" } satisfies Meta<typeof Button>; export default meta;',
+    },
+  ])("accepts a title in $form", ({ source }) => {
+    expect(hasExplicitTitle(source)).toBe(true);
+  });
+
+  it.each([
+    {
+      form: "no title",
+      source: "export default {\n  component: Button,\n};\n",
+    },
+    {
+      form: "only a title control",
+      source:
+        'const argTypes = {\n  title: {\n    control: { type: "text" },\n  },\n};\n\nexport default { component: Button, argTypes };\n',
+    },
+    {
+      form: "only a title variable",
+      source:
+        "export default {\n  component: Button,\n  args: {\n    title: defaultTitle,\n  },\n};\n",
+    },
+    {
+      form: "only a string-valued args title",
+      source: 'export default { args: { title: "Button label" } };',
+    },
+    {
+      form: "only another object's title",
+      source:
+        'const other = { title: "Other" }; export default { component: Button };',
+    },
+    {
+      form: "only a commented title",
+      source:
+        'export default {\n // title: "Components/Button",\n component: Button };',
+    },
+    {
+      form: "an empty title",
+      source: 'export default { title: "" };',
+    },
+    {
+      form: "a template literal unsupported by Storybook",
+      source: "export default { title: `Components/Button` };",
+    },
+  ])("rejects $form", ({ source }) => {
+    expect(hasExplicitTitle(source)).toBe(false);
+  });
+});
+
+describe("MAIN_APP_STORY_GLOBS", () => {
+  it("matches the same tracked files as Storybook's own story matcher", () => {
+    const specifiers = normalizeStories(getStories(), {
+      configDir: join(ROOT, ".storybook"),
+      workingDir: ROOT,
+    });
+    const built = tracked
+      .filter(
+        (file) =>
+          !file.endsWith(".mdx") &&
+          specifiers.some((specifier) =>
+            specifier.importPathMatcher.test(`./${file}`),
+          ),
+      )
+      .sort();
+
+    expect(planned.length).toBeGreaterThan(0);
+    expect(planned).toEqual(built);
+  });
+
+  it("matches no docs entries", () => {
+    expect(planned.filter((file) => file.endsWith(".mdx"))).toEqual([]);
+  });
+
+  it("matches only stories with an explicit title", () => {
+    const untitled = planned.filter(
+      (file) => !hasExplicitTitle(readFileSync(join(ROOT, file), "utf8")),
+    );
+
+    expect(untitled).toEqual([]);
+  });
+});
--- a/.github/workflows/frontend.yml
+++ b/.github/workflows/frontend.yml
@@ -118,20 +118,13 @@ jobs:
        # Resolve JOB_ID before the long test step so the ci-conductor reporter
        # below can link failures to this exact job. Best-effort.
        uses: ./.github/actions/resolve-job-id
-      - name: Download test plan
-        id: test-plan
-        if: ${{ inputs.test-plan-artifact-id != '' }}
-        continue-on-error: true
-        uses: actions/download-artifact@v8
-        with:
-          artifact-ids: ${{ inputs.test-plan-artifact-id }}
-          path: ${{ runner.temp }}/test-plan
      - name: Prepare unit test selection
        id: unit-selection
        if: ${{ inputs.test-plan-artifact-id != '' }}
-        env:
-          PLAN_DOWNLOADED: ${{ steps.test-plan.outcome }}
-        run: bun .github/scripts/prepare-unit-test-selection.ts
+        uses: ./.github/actions/prepare-test-selection
+        with:
+          suite: unit
+          test-plan-artifact-id: ${{ inputs.test-plan-artifact-id }}
      - name: Run frontend unit tests
        id: fe-tests
        env:
--- a/.github/workflows/loki.yml
+++ b/.github/workflows/loki.yml
@@ -4,16 +4,51 @@ on:
  workflow_call:
    inputs:
      skip:
+        description: "Skip the Loki visual tests."
        type: boolean
        default: false
+      test-plan-artifact-id:
+        description: "ID of this run's test-plan.json artifact, or '' to run the full suite."
+        type: string
+        default: ""

 concurrency:
  group: ${{ github.workflow }}-${{ github.head_ref && github.ref || github.run_id }}-loki
  cancel-in-progress: true

 jobs:
+  story-selection:
+    if: ${{ !inputs.skip && inputs.test-plan-artifact-id != '' }}
+    runs-on: ${{ vars.SLIM_RUNNER_KEY }}
+    timeout-minutes: 5
+    outputs:
+      selection: ${{ steps.loki-selection.outputs.selection }}
+      test-plan-artifact-id: ${{ steps.loki-selection.outputs.paths-file && inputs.test-plan-artifact-id || '' }}
+    steps:
+      - name: Checkout Repository
+        uses: actions/checkout@v6
+        with:
+          sparse-checkout: |
+            .github
+            /.nvmrc
+            /package.json
+          sparse-checkout-cone-mode: false
+
+      - name: Prepare Node + Bun environment
+        uses: ./.github/actions/prepare-node-bun
+
+      - name: Prepare Loki story selection
+        id: loki-selection
+        uses: ./.github/actions/prepare-test-selection
+        with:
+          suite: loki
+          test-plan-artifact-id: ${{ inputs.test-plan-artifact-id }}
+
  visual-test:
-    if: ${{ !inputs.skip }}
+    needs: story-selection
+    # A missing job output compares equal to '0' in GitHub expressions,
+    # so an empty selection is marked with a non-numeric value.
+    if: ${{ !cancelled() && !inputs.skip && needs.story-selection.outputs.selection != 'empty' }}
    runs-on: ${{ vars.DEFAULT_RUNNER_KEY }}
    timeout-minutes: 30
    services:
@@ -41,8 +76,22 @@ jobs:
      - name: Compile CLJS
        run: NODE_ENV=development bun run build-pure:cljs

+      - name: Prepare Loki story selection
+        id: loki-selection
+        if: ${{ needs.story-selection.outputs.test-plan-artifact-id != '' }}
+        uses: ./.github/actions/prepare-test-selection
+        with:
+          suite: loki
+          test-plan-artifact-id: ${{ needs.story-selection.outputs.test-plan-artifact-id }}
+
+      - name: Build Storybook
+        env:
+          STORYBOOK_STORY_PATHS_FILE: ${{ steps.loki-selection.outputs.paths-file }}
+        run: bun run build-storybook
+
      - name: Run Loki Visual Tests
-        run: bun run test-visual:loki:ci
+        # Loki drops stories with parameters.loki.skip, and exits non-zero when that leaves the selection empty.
+        run: bun run test-visual:loki --reactUri file:./storybook-static --verboseRenderer ${{ steps.loki-selection.outputs.paths-file && '--passWithNoStories --requireReference' || '' }}

      - name: Generate Visual Report on Failure
        if: failure()
@@ -57,3 +106,37 @@ jobs:
          include-hidden-files: true
          path: .loki/
          if-no-files-found: ignore
+
+  loki-tests-result:
+    needs: [story-selection, visual-test]
+    if: always() && !cancelled()
+    runs-on: ${{ vars.SLIM_RUNNER_KEY }}
+    timeout-minutes: 5
+    steps:
+      - name: Check Loki job status
+        uses: actions/github-script@v9
+        env:
+          needs: ${{ toJson(needs) }}
+        with:
+          script: | # js
+            const needs = JSON.parse(process.env.needs);
+            const jobs = Object.entries(needs).map(
+              ([jobName, jobValues]) => ({
+                name: jobName,
+                result: jobValues.result
+              }));
+
+            // are all jobs skipped or successful?
+            if (jobs.every(job => (job.result === 'skipped' || job.result === 'success'))) {
+              console.log('All jobs are skipped or successful');
+              process.exit(0);
+            }
+
+            // otherwise, something failed
+            console.log('Some Loki jobs failed');
+            jobs.forEach((job) => {
+              if (job.result !== 'success') {
+                console.log(`${job.name} - ${job.result}`);
+              }
+            });
+            process.exit(1);
--- a/.github/workflows/run-tests.yml
+++ b/.github/workflows/run-tests.yml
@@ -57,11 +57,10 @@ jobs:
      build_scripts: ${{ steps.changes.outputs.build_scripts }}
      embedder_plugin: ${{ steps.changes.outputs.embedder_plugin }}
      frontend_all: ${{ steps.changes.outputs.frontend_all }}
-      frontend_ci: ${{ steps.changes.outputs.frontend_ci }}
      frontend_sources: ${{ steps.changes.outputs.frontend_sources }}
      frontend_unit_infra: ${{ steps.changes.outputs.frontend_unit_infra }}
-      frontend_loki_ci: ${{ steps.changes.outputs.frontend_loki_ci }}
      frontend_loki_infra: ${{ steps.changes.outputs.frontend_loki_infra }}
+      frontend_loki_all: ${{ steps.changes.outputs.frontend_loki_all }}
      shared_sources: ${{ steps.changes.outputs.shared_sources }}
      documentation: ${{ steps.changes.outputs.documentation }}
      embedding_documentation: ${{ steps.changes.outputs.embedding_documentation }}
@@ -320,7 +319,7 @@ jobs:
        needs.files-changed.outputs.ci_scripts != 'true' }}

  loki-tests:
-    needs: [should-run, files-changed]
+    needs: [should-run, files-changed, create-test-plan]
    if: |
      !cancelled() &&
      (needs.should-run.outputs.verdict == 'force-run' ||
@@ -329,9 +328,9 @@ jobs:
    with:
      skip: >-
        ${{ needs.should-run.outputs.verdict != 'force-run' &&
-        needs.files-changed.outputs.frontend_ci != 'true' &&
-        needs.files-changed.outputs.frontend_sources != 'true' &&
-        needs.files-changed.outputs.frontend_loki_ci != 'true' }}
+        needs.files-changed.outputs.frontend_loki_all != 'true' }}
+      # A skipped/failed planner supplies no artifact, so the suite runs in full.
+      test-plan-artifact-id: ${{ needs.create-test-plan.result == 'success' && needs.create-test-plan.outputs.artifact-id || '' }}

  e2e-tests:
    needs: [should-run, files-changed, uberjar]
--- a/.storybook/main.ts
+++ b/.storybook/main.ts
@@ -12,21 +12,16 @@ const {
 } = require("../frontend/build/shared/rspack/side-effect-free-modules");
 const appConfig = require("../rspack.main.config.js");

-const mainAppStories = [
-  "../frontend/**/*.mdx",
-  "../frontend/*/!(embedding-sdk-bundle|embedding-sdk-shared)/**/*.stories.@(ts|tsx)",
-  "../enterprise/frontend/*/!(embedding-sdk-ee|embedding-sdk-package)/**/*.stories.@(ts|tsx)",
-];
-
-// Allow filtering to specific story files via env var (used by stress tests)
-// STORYBOOK_STORIES_FILTER: comma-separated file paths relative to repo root
-// e.g. "frontend/src/.../Button.stories.tsx,frontend/src/.../Alert.stories.tsx"
-const stories = process.env.STORYBOOK_STORIES_FILTER
-  ? process.env.STORYBOOK_STORIES_FILTER.split(",").map((f) => `../${f}`)
-  : mainAppStories;
+const { getStories } = require("./story-files.cjs");

 const config: StorybookConfig = {
-  stories,
+  stories: getStories({
+    pathsFile: process.env.STORYBOOK_STORY_PATHS_FILE,
+    // Allow filtering to specific story files via env var (used by stress tests)
+    // STORYBOOK_STORIES_FILTER: comma-separated file paths relative to repo root
+    // e.g. "frontend/src/.../Button.stories.tsx,frontend/src/.../Alert.stories.tsx"
+    filter: process.env.STORYBOOK_STORIES_FILTER,
+  }),
  staticDirs: [
    "../resources/frontend_client",
    "./msw-public",
--- a/.storybook/story-files.cjs
+++ b/.storybook/story-files.cjs
@@ -0,0 +1,54 @@
+const { readFileSync } = require("node:fs");
+const { resolve } = require("node:path");
+
+const ROOT = resolve(__dirname, "..");
+
+const MAIN_APP_STORY_GLOBS = [
+  "frontend/*/!(embedding-sdk-bundle|embedding-sdk-shared)/**/*.stories.@(ts|tsx)",
+  "enterprise/frontend/*/!(embedding-sdk-ee|embedding-sdk-package)/**/*.stories.@(ts|tsx)",
+];
+
+// Storybook autotitles a story from its path relative to the entry's directory,
+// so an untitled story gets a different title in a narrowed build and Loki writes a fresh reference for it.
+function hasExplicitTitle(source) {
+  // Only load the parser when validating a build; the planner also imports this
+  // module for its story globs.
+  const { loadCsf } = require("storybook/internal/csf-tools");
+  try {
+    const { meta } = loadCsf(source, { makeTitle: (title) => title }).parse();
+    return typeof meta?.title === "string" && meta.title.length > 0;
+  } catch {
+    return false;
+  }
+}
+
+function getStories({ pathsFile, filter } = {}) {
+  if (pathsFile) {
+    const files = JSON.parse(readFileSync(pathsFile, "utf8"));
+    if (
+      !Array.isArray(files) ||
+      !files.every((file) => typeof file === "string")
+    ) {
+      throw new Error("Story paths must be a JSON array of strings");
+    }
+    if (files.length === 0) {
+      throw new Error("No stories selected");
+    }
+    const untitled = files.filter(
+      (file) => !hasExplicitTitle(readFileSync(resolve(ROOT, file), "utf8")),
+    );
+    if (untitled.length > 0) {
+      throw new Error(
+        `Stories without an explicit title: ${untitled.join(", ")}`,
+      );
+    }
+    return files.map((file) => `../${file}`);
+  }
+
+  const files = filter
+    ? filter.split(",")
+    : ["frontend/**/*.mdx", ...MAIN_APP_STORY_GLOBS];
+  return files.map((file) => `../${file}`);
+}
+
+module.exports = { MAIN_APP_STORY_GLOBS, getStories, hasExplicitTitle };
--- a/eslint.config.mjs
+++ b/eslint.config.mjs
@@ -1196,6 +1196,7 @@ const configs = [
      ".github/scripts/**/*.js",
      ".github/scripts/**/*.mjs",
      ".github/scripts/**/*.ts",
+      ".storybook/*.cjs",
    ],
    languageOptions: {
      globals: {