diff --git a/.fallowrc.jsonc b/.fallowrc.jsonc
index ebf4ffe3b1..da60f32e52 100644
--- a/.fallowrc.jsonc
+++ b/.fallowrc.jsonc
@@ -517,6 +517,8 @@
       "packages/studio-server/src/routes/files.test.ts",
       "packages/studio-server/src/routes/render.test.ts",
       "packages/studio-server/src/routes/lint.test.ts",
+      // extractionCache.test.ts: pre-existing parallel describe setup and publish-case arrange/assert blocks.
+      "packages/engine/src/services/extractionCache.test.ts",
       "packages/studio-server/src/routes/preview.test.ts",
       "packages/studio-server/src/routes/projects.test.ts",
       "packages/studio-server/src/helpers/backupJournal.test.ts",
diff --git a/docs/developers/cli.mdx b/docs/developers/cli.mdx
index 0943795da8..9ec21a7486 100644
--- a/docs/developers/cli.mdx
+++ b/docs/developers/cli.mdx
@@ -19,6 +19,7 @@ remains authoritative: run `npx hyperframes <command> --help`.
 | Render a video | `npx hyperframes render --output output.mp4` |
 | Publish a browser link | `npx hyperframes publish` |
 | Diagnose the machine | `npx hyperframes doctor` |
+| Free disk space HyperFrames used | `npx hyperframes clean` |
 
 ## Work with media
 
diff --git a/docs/packages/cli.mdx b/docs/packages/cli.mdx
index 78dc13ac61..74abd1a044 100644
--- a/docs/packages/cli.mdx
+++ b/docs/packages/cli.mdx
@@ -1137,6 +1137,27 @@ In JSON mode, paths inside `detail` and `hint` are redacted — your home
 directory becomes the literal `$HOME`, so output is safe to paste into a bug
 report or an agent context.
 
+### `clean`
+
+Find and remove what HyperFrames left on disk.
+
+```bash
+npx hyperframes clean --dry-run   # list it, remove nothing
+npx hyperframes clean
+npx hyperframes clean --snapshots # also remove snapshots/ folders
+npx hyperframes clean --json
+```
+
+It looks in the current project (not its subfolders) and every project the Studio history knows, and removes:
+
+- frames and staging folders left by renders that were killed or crashed (a render that is still running keeps its own);
+- work folders of `--debug` renders nothing has written to for six hours;
+- the history of projects that no longer exist;
+- extracted video frames and video proxies nobody has used for an hour (they rebuild on demand).
+
+`snapshots/` folders are listed as also reclaimable and removed only with `--snapshots`. Rendered outputs, source
+files, the browser download and models are never touched.
+
 ### `info` and `compositions`
 
 `npx hyperframes info [dir]` prints project metadata: name, resolution,
diff --git a/packages/cli/src/cli.ts b/packages/cli/src/cli.ts
index 9d2541cd70..d886e47927 100644
--- a/packages/cli/src/cli.ts
+++ b/packages/cli/src/cli.ts
@@ -172,6 +172,7 @@ const commandLoaders = {
   tts: () => import("./commands/tts.js").then((m) => m.default),
   docs: () => import("./commands/docs.js").then((m) => m.default),
   doctor: () => import("./commands/doctor.js").then((m) => m.default),
+  clean: () => import("./commands/clean.js").then((m) => m.default),
   upgrade: () => import("./commands/upgrade.js").then((m) => m.default),
   skills: () => import("./commands/skills.js").then((m) => m.default),
   feedback: () => import("./commands/feedback.js").then((m) => m.default),
diff --git a/packages/cli/src/commands/clean.test.ts b/packages/cli/src/commands/clean.test.ts
new file mode 100644
index 0000000000..af47354f0c
--- /dev/null
+++ b/packages/cli/src/commands/clean.test.ts
@@ -0,0 +1,206 @@
+import { type ChildProcess, spawn, spawnSync } from "node:child_process";
+import {
+  chmodSync,
+  existsSync,
+  mkdirSync,
+  mkdtempSync,
+  readFileSync,
+  readdirSync,
+  realpathSync,
+  rmSync,
+  symlinkSync,
+  utimesSync,
+  writeFileSync,
+} from "node:fs";
+import { tmpdir } from "node:os";
+import { basename, join } from "node:path";
+import { runCommand } from "citty";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { createOwnedRenderDir } from "@hyperframes/producer";
+import { consumeCommandResult } from "../utils/commandResult.js";
+import cleanCommand, { cleanLeftovers } from "./clean.js";
+
+const history = vi.hoisted(() => ({ unreadable: false }));
+vi.mock("@hyperframes/studio-server", async (importOriginal) => {
+  const actual = await importOriginal<typeof import("@hyperframes/studio-server")>();
+  return {
+    ...actual,
+    listProjectHistories: (root: string) => {
+      if (history.unreadable) throw new Error("history unreadable");
+      return actual.listProjectHistories(root);
+    },
+  };
+});
+
+const JOB = "0f8c2b1e-5d3a-4c7b-9e21-6a4f0d8b3c19";
+const SEVEN_HOURS_AGO = (Date.now() - 7 * 60 * 60 * 1000) / 1000;
+
+describe("cleanLeftovers", () => {
+  let scratch: string;
+  let project: string;
+  let renders: string;
+  let liveRender: ChildProcess;
+  // This machine's real owner stamp, so planted owners differ from it only in pid.
+  let stamp: object;
+
+  /** A render temp dir holding one 1000-byte frame, optionally owned and optionally last written 7 h ago. */
+  function plant(parent: string, name: string, owner?: number, stale = false): string {
+    const dir = join(parent, name);
+    mkdirSync(dir, { recursive: true });
+    writeFileSync(join(dir, "frame_000001.jpg"), Buffer.alloc(1000));
+    if (owner) writeFileSync(join(dir, "owner.json"), JSON.stringify({ ...stamp, pid: owner }));
+    if (stale)
+      for (const path of [join(dir, "frame_000001.jpg"), dir])
+        utimesSync(path, SEVEN_HOURS_AGO, SEVEN_HOURS_AGO);
+    return dir;
+  }
+
+  const run = (overrides: { dryRun?: boolean; snapshots?: boolean } = {}) =>
+    cleanLeftovers({
+      projectDir: project,
+      dryRun: overrides.dryRun ?? false,
+      snapshots: overrides.snapshots ?? false,
+      historyRoot: join(scratch, "history"),
+      tempDir: join(scratch, "tmp"),
+      debugDir: join(scratch, "debug"),
+    });
+
+  beforeEach(() => {
+    scratch = realpathSync(mkdtempSync(join(tmpdir(), "hf-clean-")));
+    project = join(scratch, "project");
+    renders = join(project, "renders");
+    mkdirSync(renders, { recursive: true });
+    mkdirSync(join(scratch, "tmp"));
+    writeFileSync(join(project, "index.html"), '<div data-composition-id="main"></div>');
+    const own = createOwnedRenderDir(join(scratch, "self-"));
+    stamp = JSON.parse(readFileSync(join(own, "owner.json"), "utf-8"));
+    rmSync(own, { recursive: true });
+    vi.stubEnv("HYPERFRAMES_EXTRACT_CACHE_DIR", join(scratch, "extract-cache"));
+    // Stands in for a render in progress: a running process that owns its work dir.
+    liveRender = spawn(process.execPath, ["-e", "setInterval(() => {}, 1000)"], {
+      stdio: "ignore",
+    });
+  });
+  afterEach(() => {
+    liveRender.kill("SIGKILL");
+    vi.unstubAllEnvs();
+    rmSync(scratch, { recursive: true, force: true });
+  });
+
+  it("removes what dead renders left and keeps what a running render uses", async () => {
+    const dead = spawnSync(process.execPath, ["-e", ""]).pid;
+    const abandoned = plant(renders, `work-${JOB}-aB3dE9`, dead);
+    const staging = plant(renders, ".final.hf-transaction-Zx81Qa", dead);
+    const beforeOwners = plant(renders, `work-${JOB}-Oo0000`, undefined, true);
+    const oldDebug = plant(join(scratch, "debug"), JOB, undefined, true);
+    const windowsLeftover = plant(join(scratch, "tmp"), "hf-render-Qw12Er", dead);
+    const live = plant(renders, `work-${JOB}-Ll0000`, liveRender.pid);
+    const freshOwnerless = plant(renders, `work-${JOB}-Ff0000`);
+    const userFolder = plant(renders, "work-in-progress", undefined, true);
+    const debugNotes = plant(join(scratch, "debug"), "my-notes", undefined, true);
+    writeFileSync(join(renders, "final.mp4"), "the render");
+    plant(project, "snapshots");
+
+    const listed = await run({ dryRun: true });
+    expect(listed.removed.map((item) => item.path).sort()).toEqual(
+      [abandoned, staging, beforeOwners, oldDebug, windowsLeftover].sort(),
+    );
+    expect(listed.removed.every((item) => item.bytes >= 1000)).toBe(true);
+    expect(existsSync(abandoned)).toBe(true);
+
+    await run();
+    expect(readdirSync(renders).sort()).toEqual(
+      ["final.mp4", live, freshOwnerless, userFolder].map((path) => basename(path)).sort(),
+    );
+    expect(existsSync(oldDebug) || existsSync(windowsLeftover)).toBe(false);
+    expect(existsSync(debugNotes)).toBe(true);
+  });
+
+  it.skipIf(process.platform === "win32" || process.getuid?.() === 0)(
+    "reports a leftover it cannot remove and still removes the rest",
+    async () => {
+      const dead = spawnSync(process.execPath, ["-e", ""]).pid;
+      const stuck = plant(renders, `work-${JOB}-St0000`, dead);
+      const locked = join(stuck, "locked");
+      mkdirSync(locked);
+      writeFileSync(join(locked, "frame.jpg"), "x");
+      chmodSync(locked, 0o555);
+      const other = plant(join(scratch, "tmp"), "hf-render-Ot0000", dead);
+      try {
+        const result = await run();
+        expect(result.errors).toHaveLength(1);
+        expect(result.removed.map((item) => item.path)).toEqual([other]);
+        expect(existsSync(other)).toBe(false);
+      } finally {
+        chmodSync(locked, 0o755);
+      }
+    },
+  );
+
+  it("leaves snapshots alone in a folder that is not a HyperFrames project", async () => {
+    writeFileSync(join(project, "index.html"), "<title>my website</title>");
+    const snapshots = plant(project, "snapshots");
+
+    const result = await run({ snapshots: true });
+    expect(result.alsoReclaimable).toEqual([]);
+    expect(existsSync(snapshots)).toBe(true);
+  });
+
+  it.skipIf(process.platform === "win32" || process.getuid?.() === 0)(
+    "still cleans when the history folder cannot be read",
+    async () => {
+      const history = join(scratch, "history");
+      mkdirSync(history);
+      chmodSync(history, 0o000);
+      const dead = spawnSync(process.execPath, ["-e", ""]).pid;
+      const leftover = plant(join(scratch, "tmp"), "hf-render-Hi0000", dead);
+      try {
+        const result = await run();
+        expect(result.errors.length).toBeGreaterThan(0);
+        expect(existsSync(leftover)).toBe(false);
+      } finally {
+        chmodSync(history, 0o755);
+      }
+    },
+  );
+
+  it("lists a leftover once when the project folder is a link to the temp dir", async () => {
+    const dead = spawnSync(process.execPath, ["-e", ""]).pid;
+    const leftover = plant(join(scratch, "tmp"), "hf-render-Ln0000", dead);
+    symlinkSync(join(scratch, "tmp"), join(scratch, "tmp-link"));
+
+    const result = await cleanLeftovers({
+      projectDir: join(scratch, "tmp-link"),
+      dryRun: true,
+      snapshots: false,
+      historyRoot: join(scratch, "history"),
+      tempDir: join(scratch, "tmp"),
+      debugDir: join(scratch, "debug"),
+    });
+    expect(result.removed.map((item) => item.path)).toEqual([leftover]);
+  });
+
+  it("exits 1 when something could not be read or removed", async () => {
+    history.unreadable = true;
+    const log = vi.spyOn(console, "log").mockImplementation(() => {});
+    try {
+      await runCommand(cleanCommand, { rawArgs: [project, "--dry-run", "--json"] });
+      expect(JSON.parse(String(log.mock.calls.at(-1)?.[0])).errors).toContain("history unreadable");
+      expect(consumeCommandResult().exitCode).toBe(1);
+    } finally {
+      history.unreadable = false;
+      log.mockRestore();
+    }
+  });
+
+  it("lists snapshots as reclaimable and removes them only when asked", async () => {
+    const snapshots = plant(project, "snapshots");
+
+    const plain = await run();
+    expect(plain.alsoReclaimable).toEqual([{ what: "Snapshots", path: snapshots, bytes: 1000 }]);
+    expect(existsSync(snapshots)).toBe(true);
+
+    await run({ snapshots: true });
+    expect(existsSync(snapshots)).toBe(false);
+  });
+});
diff --git a/packages/cli/src/commands/clean.ts b/packages/cli/src/commands/clean.ts
new file mode 100644
index 0000000000..cd1e6e2e2c
--- /dev/null
+++ b/packages/cli/src/commands/clean.ts
@@ -0,0 +1,274 @@
+import { existsSync, readFileSync, realpathSync, rmSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join, resolve } from "node:path";
+import { defineCommand } from "citty";
+import {
+  EXTRACT_CACHE_MIN_AGE_MS,
+  directorySizeBytes,
+  gcExtractionCache,
+  resolveExtractCacheDir,
+} from "@hyperframes/engine";
+import {
+  DEFAULT_HISTORY_ROOT,
+  PROXY_CACHE_DIR_NAME,
+  cleanupProxyCache,
+  listProjectHistories,
+  pruneGoneProjectHistories,
+} from "@hyperframes/studio-server";
+import type { Example } from "./_examples.js";
+import { c } from "../ui/colors.js";
+import { formatBytes } from "../ui/format.js";
+import { setCommandExitCode } from "../utils/commandResult.js";
+import { loadProducer } from "../utils/producer.js";
+import { redactHome } from "./doctor.js";
+import { withMeta } from "../utils/updateCheck.js";
+
+export const examples: Example[] = [
+  ["See what HyperFrames left on disk, remove nothing", "hyperframes clean --dry-run"],
+  ["Remove it", "hyperframes clean"],
+  ["Also remove snapshot folders", "hyperframes clean --snapshots"],
+  ["For agents", "hyperframes clean --json"],
+];
+
+/** A render dir with no owner record (made before owners were recorded) counts as abandoned after this long idle. */
+const OWNERLESS_IDLE_MS = 6 * 60 * 60 * 1000;
+/** A video proxy nobody has used for this long is regenerable; a Studio still using one keeps touching it. */
+const PROXY_IDLE_MS = 60 * 60 * 1000;
+
+export interface Leftover {
+  what: string;
+  path: string;
+  bytes: number;
+}
+
+export interface CleanOptions {
+  projectDir: string;
+  dryRun: boolean;
+  snapshots: boolean;
+  /** Where to look; each defaults to the real location (tests point them at scratch dirs). */
+  historyRoot?: string;
+  tempDir?: string;
+  debugDir?: string;
+}
+
+export interface CleanResult {
+  removed: Leftover[];
+  alsoReclaimable: Leftover[];
+  errors: string[];
+}
+
+interface Sweep {
+  dryRun: boolean;
+  result: CleanResult;
+}
+
+function recordError(sweep: Sweep, error: unknown): void {
+  sweep.result.errors.push(error instanceof Error ? error.message : String(error));
+}
+
+/** Runs one kind of sweep; a failure is reported and the rest of the clean goes on. */
+async function attempt(sweep: Sweep, step: () => unknown): Promise<void> {
+  try {
+    await step();
+  } catch (error) {
+    recordError(sweep, error);
+  }
+}
+
+/** A HyperFrames project: its index.html holds a composition root, not just any website. */
+function isProject(dir: string): boolean {
+  try {
+    return readFileSync(join(dir, "index.html"), "utf-8").includes("data-composition-id");
+  } catch {
+    return false;
+  }
+}
+
+function realDir(dir: string): string {
+  try {
+    return realpathSync(dir);
+  } catch {
+    return resolve(dir);
+  }
+}
+
+function knownProjectDirs(sweep: Sweep, historyRoot: string): string[] {
+  try {
+    return listProjectHistories(historyRoot).map((record) => record.projectDir);
+  } catch (error) {
+    recordError(sweep, error);
+    return [];
+  }
+}
+
+function drop(sweep: Sweep, what: string, path: string): void {
+  const bytes = directorySizeBytes(path);
+  try {
+    if (!sweep.dryRun)
+      rmSync(path, { recursive: true, force: true, maxRetries: 3, retryDelay: 100 });
+    sweep.result.removed.push({ what, path, bytes });
+  } catch (error) {
+    recordError(sweep, error);
+  }
+}
+
+function sweepProxies(sweep: Sweep, project: string): void {
+  const proxies = join(project, PROXY_CACHE_DIR_NAME);
+  const swept = cleanupProxyCache(proxies, {
+    maxBytes: Number.POSITIVE_INFINITY,
+    maxIdleMs: PROXY_IDLE_MS,
+    minSweepIntervalMs: 0,
+    dryRun: sweep.dryRun,
+  });
+  if (swept.removed.length === 0) return;
+  sweep.result.removed.push({
+    what: "Video proxies",
+    path: proxies,
+    bytes: swept.bytesBefore - swept.bytesAfter,
+  });
+}
+
+function sweepSnapshots(sweep: Sweep, project: string, remove: boolean): void {
+  const snapshots = join(project, "snapshots");
+  if (!existsSync(snapshots)) return;
+  if (remove) drop(sweep, "Snapshots", snapshots);
+  else
+    sweep.result.alsoReclaimable.push({
+      what: "Snapshots",
+      path: snapshots,
+      bytes: directorySizeBytes(snapshots),
+    });
+}
+
+async function sweepHistories(sweep: Sweep, historyRoot: string, tempDir: string): Promise<void> {
+  const pruned = await pruneGoneProjectHistories(historyRoot, {
+    dryRun: sweep.dryRun,
+    onError: (error) => recordError(sweep, error),
+    tempDir,
+  });
+  for (const history of pruned) {
+    sweep.result.removed.push({
+      what: "Project history",
+      path: join(historyRoot, history.id),
+      bytes: history.bytes,
+    });
+  }
+}
+
+function sweepExtractCache(sweep: Sweep): void {
+  const extractCache = resolveExtractCacheDir().dir;
+  if (!extractCache) return;
+  const swept = gcExtractionCache(extractCache, {
+    maxBytes: 0,
+    minAgeMs: EXTRACT_CACHE_MIN_AGE_MS,
+    dryRun: sweep.dryRun,
+  });
+  if (swept.evictedEntries + swept.agedPartialsRemoved === 0) return;
+  sweep.result.removed.push({
+    what: "Extracted video frames",
+    path: extractCache,
+    bytes: swept.evictedBytes,
+  });
+}
+
+/** Everything HyperFrames left behind that no running render or preview uses; removed unless `dryRun`. */
+export async function cleanLeftovers(options: CleanOptions): Promise<CleanResult> {
+  const historyRoot = options.historyRoot ?? DEFAULT_HISTORY_ROOT;
+  const tempDir = options.tempDir ?? tmpdir();
+  const { RENDER_JOB_DIR, listAbandonedRenderDirs, resolveRenderDebugDir } = await loadProducer();
+  const sweep: Sweep = {
+    dryRun: options.dryRun,
+    result: { removed: [], alsoReclaimable: [], errors: [] },
+  };
+  const dropAbandoned = (what: string, parent: string, names?: RegExp) => {
+    for (const dir of listAbandonedRenderDirs(parent, {
+      ownerlessIdleMs: OWNERLESS_IDLE_MS,
+      names,
+    }))
+      drop(sweep, what, dir);
+  };
+
+  const projects = new Set(
+    [options.projectDir, ...knownProjectDirs(sweep, historyRoot)].map(realDir),
+  );
+  const renderParents = new Set([
+    ...[...projects].flatMap((project) => [project, join(project, "renders")]),
+    realDir(tempDir),
+  ]);
+  for (const parent of renderParents) dropAbandoned("Render leftovers", parent);
+  dropAbandoned("Debug renders", options.debugDir ?? resolveRenderDebugDir(), RENDER_JOB_DIR);
+  for (const project of projects) {
+    if (!isProject(project)) continue;
+    await attempt(sweep, () => sweepProxies(sweep, project));
+    sweepSnapshots(sweep, project, options.snapshots);
+  }
+  await attempt(sweep, () => sweepHistories(sweep, historyRoot, tempDir));
+  await attempt(sweep, () => sweepExtractCache(sweep));
+  return sweep.result;
+}
+
+function printTable(rows: Leftover[]): void {
+  const whatWidth = Math.max(...rows.map((row) => row.what.length));
+  for (const row of rows) {
+    console.log(
+      `  ${row.what.padEnd(whatWidth)}  ${formatBytes(row.bytes).padStart(9)}  ${c.dim(row.path)}`,
+    );
+  }
+}
+
+const total = (rows: Leftover[]) => rows.reduce((sum, row) => sum + row.bytes, 0);
+const redactPaths = (rows: Leftover[]) =>
+  rows.map((row) => ({ ...row, path: redactHome(row.path) }));
+
+export default defineCommand({
+  meta: { name: "clean", description: "Find and remove what HyperFrames left on disk" },
+  args: {
+    dir: {
+      type: "positional",
+      description: "Project directory (default: current); its subfolders are not searched",
+      required: false,
+    },
+    "dry-run": {
+      type: "boolean",
+      description: "List what would be removed, remove nothing",
+      default: false,
+    },
+    snapshots: { type: "boolean", description: "Also remove snapshots/ folders", default: false },
+    json: { type: "boolean", description: "Output as JSON", default: false },
+  },
+  async run({ args }) {
+    const dryRun = args["dry-run"];
+    const result = await cleanLeftovers({
+      projectDir: args.dir ?? process.cwd(),
+      dryRun,
+      snapshots: args.snapshots,
+    });
+    if (result.errors.length > 0) setCommandExitCode(1);
+    if (args.json) {
+      const report = withMeta({
+        dryRun,
+        removed: redactPaths(result.removed),
+        alsoReclaimable: redactPaths(result.alsoReclaimable),
+        errors: result.errors.map(redactHome),
+        totalBytes: total(result.removed),
+      });
+      console.log(JSON.stringify(report, null, 2));
+      return;
+    }
+    if (result.removed.length === 0) {
+      console.log(`${c.success("◇")}  Nothing to clean`);
+    } else {
+      console.log(
+        `${c.success("◇")}  ${dryRun ? "Would remove" : "Removed"} ${formatBytes(total(result.removed))}`,
+      );
+      printTable(result.removed);
+    }
+    if (result.alsoReclaimable.length > 0) {
+      console.log(
+        `\n   Also reclaimable with --snapshots: ${formatBytes(total(result.alsoReclaimable))}`,
+      );
+      printTable(result.alsoReclaimable);
+    }
+    for (const error of result.errors) console.log(c.warn(`  ${error}`));
+  },
+});
diff --git a/packages/cli/src/help.ts b/packages/cli/src/help.ts
index 37173e9b98..236c919cd4 100644
--- a/packages/cli/src/help.ts
+++ b/packages/cli/src/help.ts
@@ -71,6 +71,7 @@ const GROUPS: Group[] = [
       ],
       ["browser", "Manage the Chrome browser used for rendering"],
       ["doctor", "Check system dependencies and environment"],
+      ["clean", "Find and remove what HyperFrames left on disk"],
       ["upgrade", "Check for updates and show upgrade instructions"],
     ],
   },
diff --git a/packages/engine/src/index.ts b/packages/engine/src/index.ts
index 4b98af1600..fb90a59be9 100644
--- a/packages/engine/src/index.ts
+++ b/packages/engine/src/index.ts
@@ -232,7 +232,9 @@ export {
   type VideoFrameFormat,
   VIDEO_FRAME_FORMATS,
   isVideoFrameFormat,
+  EXTRACT_CACHE_MIN_AGE_MS,
 } from "./services/videoFrameExtractor.js";
+export { directorySizeBytes, gcExtractionCache } from "./services/extractionCache.js";
 
 export {
   resolveReferencedStart,
diff --git a/packages/engine/src/services/extractionCache.test.ts b/packages/engine/src/services/extractionCache.test.ts
index d3bf36e665..01c1840921 100644
--- a/packages/engine/src/services/extractionCache.test.ts
+++ b/packages/engine/src/services/extractionCache.test.ts
@@ -416,6 +416,19 @@ describe("gcExtractionCache", () => {
     expect(stats.evictedEntries).toBe(1);
   });
 
+  it("counts the same evictions in a dry run and removes nothing", () => {
+    const old = makeEntry("old", 60, 120_000);
+    const young = makeEntry("young", 60, 1_000);
+    const options = { maxBytes: 0, minAgeMs: 60_000 };
+
+    const planned = gcExtractionCache(tmpRoot, { ...options, dryRun: true });
+    expect(existsSync(old)).toBe(true);
+    expect(gcExtractionCache(tmpRoot, options)).toEqual(planned);
+    expect(planned.evictedEntries).toBe(1);
+    expect(existsSync(old)).toBe(false);
+    expect(existsSync(young)).toBe(true);
+  });
+
   it("evicts oldest complete entries first until under maxBytes while respecting minAge", () => {
     const oldest = makeEntry("oldest", 60, 120_000);
     const middle = makeEntry("middle", 60, 90_000);
diff --git a/packages/engine/src/services/extractionCache.ts b/packages/engine/src/services/extractionCache.ts
index 668d445beb..f7a12406e2 100644
--- a/packages/engine/src/services/extractionCache.ts
+++ b/packages/engine/src/services/extractionCache.ts
@@ -336,7 +336,7 @@ function isPartialChild(name: string): boolean {
   return name.includes(".partial-");
 }
 
-function directorySizeBytes(path: string): number {
+export function directorySizeBytes(path: string): number {
   try {
     const stat = lstatSync(path);
     if (!stat.isDirectory()) return stat.size;
@@ -394,11 +394,12 @@ function collectGcEntry(
   now: number,
   minAgeMs: number,
   stats: GcStats,
+  remove: (dir: string) => void,
 ): GcEntry | null {
   try {
     const dirStat = statSync(dir);
     if (isPartialChild(name) && now - dirStat.mtimeMs >= minAgeMs) {
-      removeDir(dir);
+      remove(dir);
       stats.agedPartialsRemoved += 1;
       return null;
     }
@@ -445,16 +446,21 @@ export function gcSweepDue(rootDir: string, maxAgeMs: number): boolean {
   }
 }
 
-export function gcExtractionCache(
-  rootDir: string,
-  opts: { maxBytes: number; minAgeMs: number },
-): GcStats {
-  const stats: GcStats = { evictedEntries: 0, evictedBytes: 0, agedPartialsRemoved: 0 };
+function markGcSweep(rootDir: string): void {
   try {
     writeFileSync(join(rootDir, GC_MARKER), "", "utf-8");
   } catch {
     // Unwritable root: the sweep below will no-op on the same root anyway.
   }
+}
+
+export function gcExtractionCache(
+  rootDir: string,
+  opts: { maxBytes: number; minAgeMs: number; dryRun?: boolean },
+): GcStats {
+  const stats: GcStats = { evictedEntries: 0, evictedBytes: 0, agedPartialsRemoved: 0 };
+  const remove = opts.dryRun ? () => {} : removeDir;
+  if (!opts.dryRun) markGcSweep(rootDir);
   try {
     const now = Date.now();
     const entries: GcEntry[] = [];
@@ -466,6 +472,7 @@ export function gcExtractionCache(
         now,
         opts.minAgeMs,
         stats,
+        remove,
       );
       if (entry) entries.push(entry);
     }
@@ -477,7 +484,7 @@ export function gcExtractionCache(
     for (const entry of entries) {
       // ponytail: age-based liveness guard, not a lock; a render longer than minAge with a full cache could lose entries mid-read - acceptable, next render re-extracts.
       if (entry.ageMs < opts.minAgeMs) continue;
-      removeDir(entry.dir);
+      remove(entry.dir);
       stats.evictedEntries += 1;
       stats.evictedBytes += entry.size;
       totalBytes -= entry.size;
diff --git a/packages/engine/src/services/videoFrameExtractor.ts b/packages/engine/src/services/videoFrameExtractor.ts
index dbaa4948a3..32d182ed51 100644
--- a/packages/engine/src/services/videoFrameExtractor.ts
+++ b/packages/engine/src/services/videoFrameExtractor.ts
@@ -219,7 +219,7 @@ export interface ExtractionOptions {
   collectProbeFailures?: boolean;
 }
 
-const EXTRACT_CACHE_MIN_AGE_MS = 60 * 60 * 1000;
+export const EXTRACT_CACHE_MIN_AGE_MS = 60 * 60 * 1000;
 const GC_STALENESS_MS = 24 * 60 * 60 * 1000;
 const SDR_TO_HDR_COLORSPACE_FILTER = "colorspace=all=bt2020:iall=bt709:range=tv";
 const HDR_TO_SDR_ZSCALE_TRANSFORM_KEY = "hdr2sdr-hable-srgb";
@@ -2468,6 +2468,10 @@ export class FrameLookupTable {
     return frameIndex == null ? null : video.extracted.framePaths.get(frameIndex) || null;
   }
 
+  frameDirs(): string[] {
+    return [...new Set(Array.from(this.videos.values(), (video) => video.extracted.outputDir))];
+  }
+
   private resetActiveState(): void {
     this.activeVideoIds.clear();
     this.startCursor = 0;
diff --git a/packages/engine/src/services/videoFrameInjector.test.ts b/packages/engine/src/services/videoFrameInjector.test.ts
index f49caf4e7b..cda432c312 100644
--- a/packages/engine/src/services/videoFrameInjector.test.ts
+++ b/packages/engine/src/services/videoFrameInjector.test.ts
@@ -2,7 +2,7 @@
 import { describe, it, expect, beforeEach, afterEach, vi } from "vitest";
 import { mkdtempSync, rmSync, statSync, utimesSync, writeFileSync } from "node:fs";
 import { tmpdir } from "node:os";
-import { join } from "node:path";
+import { dirname, join } from "node:path";
 import { type Page } from "puppeteer-core";
 import { COMPLETE_SENTINEL } from "./extractionCache.js";
 
@@ -25,7 +25,7 @@ vi.mock("./screenshotService.js", () => ({
 }));
 
 import { __testing, createVideoFrameInjector } from "./videoFrameInjector.js";
-import { type FrameLookupTable } from "./videoFrameExtractor.js";
+import { type ExtractedFrames, FrameLookupTable } from "./videoFrameExtractor.js";
 import { type BeforeCaptureHook } from "./frameCapture.js";
 import { DEFAULT_CONFIG } from "../config.js";
 
@@ -178,6 +178,7 @@ describe("createVideoFrameInjector cache hygiene against page-side skips", () =>
   // table is exercised exhaustively in videoFrameExtractor.test.ts.
   function fakeTable(payload: { videoId: string; framePath: string; frameIndex: number }) {
     return {
+      frameDirs: () => [],
       getActiveFramePayloads: () =>
         new Map([
           [payload.videoId, { framePath: payload.framePath, frameIndex: payload.frameIndex }],
@@ -338,6 +339,7 @@ describe("createVideoFrameInjector extraction-cache lease renewal", () => {
 
   function makeHook(framePath: string): BeforeCaptureHook {
     const table = {
+      frameDirs: () => [dirname(framePath)],
       getActiveFramePayloads: () => new Map([["v", { framePath, frameIndex: 0 }]]),
     } as unknown as FrameLookupTable;
     const hook = createVideoFrameInjector(table, { frameSrcResolver: inlineResolver });
@@ -378,6 +380,18 @@ describe("createVideoFrameInjector extraction-cache lease renewal", () => {
     expect(sentinelMtimeMs()).toBeGreaterThan(before);
   });
 
+  it("renews the entry of a clip that is not on screen yet", async () => {
+    const table = new FrameLookupTable();
+    const lateClip = { videoId: "late", outputDir: cacheDir, framePaths: new Map() };
+    table.addVideo(lateClip as unknown as ExtractedFrames, 3600, 3660, 0);
+    const hook = createVideoFrameInjector(table, { frameSrcResolver: inlineResolver });
+    const before = sentinelMtimeMs();
+
+    await hook?.(fakePage, 0);
+
+    expect(sentinelMtimeMs()).toBeGreaterThan(before);
+  });
+
   it("throttles renewal so repeated frames don't hammer the filesystem clock", async () => {
     const hook = makeHook(join(cacheDir, "frame_00001.jpg"));
 
diff --git a/packages/engine/src/services/videoFrameInjector.ts b/packages/engine/src/services/videoFrameInjector.ts
index f04bb1e5bc..f90225ed05 100644
--- a/packages/engine/src/services/videoFrameInjector.ts
+++ b/packages/engine/src/services/videoFrameInjector.ts
@@ -9,7 +9,6 @@
 
 import { type Page } from "puppeteer-core";
 import { promises as fs } from "fs";
-import { dirname } from "node:path";
 import { type FrameLookupTable } from "./videoFrameExtractor.js";
 import { touchCacheDir } from "./extractionCache.js";
 import { injectVideoFramesBatch, syncVideoFrameVisibility } from "./screenshotService.js";
@@ -191,13 +190,12 @@ export function createVideoFrameInjector(
   const lastCacheTouchByDir = new Map<string, number>();
 
   /**
-   * Renew this render's lease on the extraction-cache entry `framePath` lives
-   * in. Called for every active video on every frame — including one whose
-   * frame index hasn't moved, since a long-held-static frame needs its entry
-   * kept alive just as much as a changing one — so it throttles per directory.
+   * Renew this render's lease on an extraction-cache entry it reads from. Called
+   * on every frame for every entry the render holds, including clips not on
+   * screen yet (one that first shows an hour in still needs its frames), so it
+   * throttles per directory.
    */
-  function renewCacheLease(framePath: string): void {
-    const cacheDir = dirname(framePath);
+  function renewCacheLease(cacheDir: string): void {
     const now = Date.now();
     const lastTouch = lastCacheTouchByDir.get(cacheDir);
     if (lastTouch !== undefined && now - lastTouch < CACHE_TOUCH_THROTTLE_MS) return;
@@ -207,6 +205,7 @@ export function createVideoFrameInjector(
 
   // fallow-ignore-next-line complexity
   return async (page: Page, time: number) => {
+    for (const cacheDir of frameLookup.frameDirs()) renewCacheLease(cacheDir);
     const activePayloads = frameLookup.getActiveFramePayloads(time);
 
     const updates: Array<{ videoId: string; dataUri: string; frameIndex: number }> = [];
@@ -216,7 +215,6 @@ export function createVideoFrameInjector(
         [];
       for (const [videoId, payload] of activePayloads) {
         activeIds.add(videoId);
-        renewCacheLease(payload.framePath);
         const lastFrameIndex = lastInjectedFrameByVideo.get(videoId);
         if (lastFrameIndex === payload.frameIndex) continue;
         pendingReads.push(
diff --git a/packages/producer/src/index.ts b/packages/producer/src/index.ts
index d8ecb626d0..ae9ad20660 100644
--- a/packages/producer/src/index.ts
+++ b/packages/producer/src/index.ts
@@ -10,6 +10,7 @@
 export {
   createRenderJob,
   executeRenderJob,
+  resolveRenderDebugDir,
   RenderCancelledError,
   RenderQualityError,
   applyRenderWarningPolicy,
@@ -23,6 +24,11 @@ export {
   type RenderPerfSummary,
   type ProgressCallback,
 } from "./services/renderOrchestrator.js";
+export {
+  RENDER_JOB_DIR,
+  createOwnedRenderDir,
+  listAbandonedRenderDirs,
+} from "./services/render/renderDirOwner.js";
 export {
   RENDER_REQUEST_VERSION,
   createRenderRequest,
diff --git a/packages/producer/src/services/render/renderDirOwner.ts b/packages/producer/src/services/render/renderDirOwner.ts
index c9651fcabb..2b546075ac 100644
--- a/packages/producer/src/services/render/renderDirOwner.ts
+++ b/packages/producer/src/services/render/renderDirOwner.ts
@@ -1,5 +1,6 @@
 import {
   existsSync,
+  lstatSync,
   mkdtempSync,
   readFileSync,
   readdirSync,
@@ -16,6 +17,8 @@ export const TRANSACTION_BACKUP = "backup";
 // The names mkdtemp gives a render's temp dirs: work-<job uuid>-, hf-render- (Windows) and .<output>.hf-transaction-.
 const RENDER_TEMP_DIR =
   /^(work-[0-9a-f]{8}(-[0-9a-f]{4}){3}-[0-9a-f]{12}|hf-render|\..+\.hf-transaction)-[A-Za-z0-9]{6}$/;
+/** A `--debug` render's work dir, named by its job id. */
+export const RENDER_JOB_DIR = /^[0-9a-f]{8}(-[0-9a-f]{4}){3}-[0-9a-f]{12}$/;
 
 /**
  * Where a pid means this process: host and boot, plus the Linux pid namespace. Containers and machines on a shared
@@ -56,56 +59,88 @@ function alive(pid: number): boolean {
   }
 }
 
-/**
- * True only for an owner in this process's pid scope that has exited; no owner file, another scope or an unreadable
- * owner all mean "not provably abandoned".
- */
-function ownerIsGone(dir: string): boolean {
-  let owner: { pid?: unknown; host?: unknown; boot?: unknown; pidns?: unknown };
+type OwnerRecord = { pid?: unknown; host?: unknown; boot?: unknown; pidns?: unknown };
+
+function inThisPidScope(owner: OwnerRecord): boolean {
+  const scope = pidScope();
+  return owner.host === scope.host && owner.boot === scope.boot && owner.pidns === scope.pidns;
+}
+
+/** "gone" only for an owner in this pid scope that has exited; "none" when there is no owner file, else "unknown". */
+function ownerState(dir: string): "gone" | "live" | "unknown" | "none" {
+  let owner: OwnerRecord;
   try {
     owner = JSON.parse(readFileSync(join(dir, OWNER_FILE), "utf-8"));
-  } catch {
-    return false;
+  } catch (error) {
+    return (error as NodeJS.ErrnoException).code === "ENOENT" ? "none" : "unknown";
   }
-  const scope = pidScope();
   const { pid } = owner;
-  return (
-    owner.host === scope.host &&
-    owner.boot === scope.boot &&
-    owner.pidns === scope.pidns &&
-    typeof pid === "number" &&
-    Number.isInteger(pid) &&
-    pid > 0 &&
-    !alive(pid)
+  if (!inThisPidScope(owner) || typeof pid !== "number" || !Number.isInteger(pid) || pid <= 0) {
+    return "unknown";
+  }
+  return alive(pid) ? "live" : "gone";
+}
+
+function newestWriteMs(path: string): number {
+  const stat = lstatSync(path);
+  if (!stat.isDirectory()) return stat.mtimeMs;
+  return readdirSync(path).reduce(
+    (newest, name) => Math.max(newest, newestWriteMs(join(path, name))),
+    stat.mtimeMs,
   );
 }
 
-/** A staging dir that still holds {@link TRANSACTION_BACKUP} (its render died mid-swap) is left alone. */
-function removeAbandonedRenderDirs(parent: string): void {
+function isAbandoned(dir: string, ownerlessIdleMs: number | undefined, now: number): boolean {
+  try {
+    if (!lstatSync(dir).isDirectory() || existsSync(join(dir, TRANSACTION_BACKUP))) return false;
+    const owner = ownerState(dir);
+    if (owner === "gone") return true;
+    return (
+      owner === "none" &&
+      ownerlessIdleMs !== undefined &&
+      now - newestWriteMs(dir) >= ownerlessIdleMs
+    );
+  } catch {
+    // Vanished or unreadable mid-scan: not provably abandoned.
+    return false;
+  }
+}
+
+export interface AbandonedRenderDirOptions {
+  /** Also count dirs with no owner record once nothing in them has been written for this long. */
+  ownerlessIdleMs?: number;
+  /** Names to consider instead of render temp dir names. */
+  names?: RegExp;
+}
+
+/** Render temp dirs under `parent` no running render owns; never a staging dir holding {@link TRANSACTION_BACKUP}. */
+export function listAbandonedRenderDirs(
+  parent: string,
+  options: AbandonedRenderDirOptions = {},
+): string[] {
   let names: string[];
   try {
     names = readdirSync(parent);
   } catch {
-    return;
-  }
-  for (const name of names) {
-    const dir = join(parent, name);
-    if (
-      !RENDER_TEMP_DIR.test(name) ||
-      !ownerIsGone(dir) ||
-      existsSync(join(dir, TRANSACTION_BACKUP))
-    )
-      continue;
-    try {
-      rmSync(dir, { recursive: true, force: true, maxRetries: 3, retryDelay: 100 });
-    } catch {
-      // Reclaiming a dead render's dir is best-effort; it must never fail the render that found it.
-    }
+    return [];
   }
+  const now = Date.now();
+  return names
+    .filter((name) => (options.names ?? RENDER_TEMP_DIR).test(name))
+    .map((name) => join(parent, name))
+    .filter((dir) => isAbandoned(dir, options.ownerlessIdleMs, now));
 }
 
 /** Creates a render's work dir after reclaiming dirs of renders that were killed outright (no cleanup ran). */
 export function createRenderWorkDir(prefix: string, outputDir: string): string {
-  for (const dir of new Set([outputDir, dirname(prefix)])) removeAbandonedRenderDirs(dir);
+  for (const parent of new Set([outputDir, dirname(prefix)])) {
+    for (const dir of listAbandonedRenderDirs(parent)) {
+      try {
+        rmSync(dir, { recursive: true, force: true, maxRetries: 3, retryDelay: 100 });
+      } catch {
+        // Reclaiming a dead render's dir is best-effort; it must never fail the render that found it.
+      }
+    }
+  }
   return createOwnedRenderDir(prefix);
 }
diff --git a/packages/producer/src/services/renderOrchestrator.ts b/packages/producer/src/services/renderOrchestrator.ts
index 54167745cf..d3f814f115 100644
--- a/packages/producer/src/services/renderOrchestrator.ts
+++ b/packages/producer/src/services/renderOrchestrator.ts
@@ -2825,6 +2825,14 @@ function deVerifyFallbackTelemetry(err: unknown): {
   };
 }
 
+/** Where `--debug` renders keep their work dirs, one per job id. */
+export function resolveRenderDebugDir(): string {
+  const producerRoot = process.env.PRODUCER_RENDERS_DIR
+    ? resolve(process.env.PRODUCER_RENDERS_DIR, "..")
+    : resolve(dirname(fileURLToPath(import.meta.url)), "../..");
+  return join(producerRoot, ".debug");
+}
+
 /**
  * Render a `RenderJob` end-to-end: compile → probe → extract videos →
  * audio → capture → encode → assemble. The function body is a thin
@@ -2846,11 +2854,7 @@ export async function executeRenderJob(
   // Ahead of the work dir / log file / execution context: a config the format
   // cannot honor must fail before anything is written to disk.
   validateHlsRenderConfig(job.config);
-  const moduleDir = dirname(fileURLToPath(import.meta.url));
-  const producerRoot = process.env.PRODUCER_RENDERS_DIR
-    ? resolve(process.env.PRODUCER_RENDERS_DIR, "..")
-    : resolve(moduleDir, "../..");
-  const debugDir = join(producerRoot, ".debug");
+  const debugDir = resolveRenderDebugDir();
   const outputDir = dirname(outputPath);
   if (!existsSync(outputDir)) mkdirSync(outputDir, { recursive: true });
   const workDir = job.config.debug
diff --git a/packages/studio-server/src/helpers/proxyCache.test.ts b/packages/studio-server/src/helpers/proxyCache.test.ts
index 4687175976..2515463a01 100644
--- a/packages/studio-server/src/helpers/proxyCache.test.ts
+++ b/packages/studio-server/src/helpers/proxyCache.test.ts
@@ -1,6 +1,7 @@
+import { createHash, randomUUID } from "node:crypto";
 import { existsSync, mkdirSync, mkdtempSync, rmSync, utimesSync, writeFileSync } from "node:fs";
 import { tmpdir } from "node:os";
-import { join } from "node:path";
+import { basename, join } from "node:path";
 import { afterEach, describe, expect, it } from "vitest";
 import { cleanupProxyCache } from "./proxyCache.js";
 
@@ -14,6 +15,10 @@ function cacheDir(): string {
   return cache;
 }
 
+/** A proxy path named the way the transcoder names one. */
+const proxy = (cache: string, label: string, extension = ".mp4") =>
+  join(cache, `${createHash("sha256").update(label).digest("hex")}${extension}`);
+
 function writeEntry(path: string, bytes: number, modifiedAt: number): void {
   writeFileSync(path, Buffer.alloc(bytes));
   const date = new Date(modifiedAt);
@@ -28,9 +33,9 @@ describe("cleanupProxyCache", () => {
   it("removes idle and oldest entries until the cache is within its byte budget", () => {
     const cache = cacheDir();
     const now = 1_800_000_000_000;
-    const expired = join(cache, "expired.mp4");
-    const oldest = join(cache, "oldest.mp4");
-    const newest = join(cache, "newest.mp4");
+    const expired = proxy(cache, "expired");
+    const oldest = proxy(cache, "oldest");
+    const newest = proxy(cache, "newest");
     writeEntry(expired, 4, now - 31 * 24 * 60 * 60 * 1000);
     writeEntry(oldest, 6, now - 3_000);
     writeEntry(newest, 6, now - 1_000);
@@ -49,11 +54,30 @@ describe("cleanupProxyCache", () => {
     expect(existsSync(newest)).toBe(true);
   });
 
+  it("reports the same removals in a dry run and removes nothing", () => {
+    const cache = cacheDir();
+    const now = 1_800_000_000_000;
+    const idle = proxy(cache, "idle");
+    const older = proxy(cache, "older");
+    const recent = proxy(cache, "recent");
+    writeEntry(idle, 4, now - 2 * 60 * 60 * 1000);
+    writeEntry(older, 3, now - 10_000);
+    writeEntry(recent, 6, now - 1_000);
+    const options = { now, maxBytes: 7, maxIdleMs: 60 * 60 * 1000, minSweepIntervalMs: 0 };
+
+    const planned = cleanupProxyCache(cache, { ...options, dryRun: true });
+    expect(existsSync(idle)).toBe(true);
+    expect(cleanupProxyCache(cache, options)).toEqual(planned);
+    expect(planned).toMatchObject({ removed: [idle, older], bytesBefore: 13, bytesAfter: 6 });
+    expect(existsSync(idle)).toBe(false);
+    expect(existsSync(recent)).toBe(true);
+  });
+
   it("counts and evicts WebM proxies alongside MP4 proxies", () => {
     const cache = cacheDir();
     const now = 1_800_000_000_000;
-    const webm = join(cache, "alpha.webm");
-    const mp4 = join(cache, "opaque.mp4");
+    const webm = proxy(cache, "alpha", ".webm");
+    const mp4 = proxy(cache, "opaque");
     writeEntry(webm, 6, now - 2_000);
     writeEntry(mp4, 6, now - 1_000);
 
@@ -72,8 +96,8 @@ describe("cleanupProxyCache", () => {
   it("preserves in-flight entries and removes stale temporary files", () => {
     const cache = cacheDir();
     const now = 1_800_000_000_000;
-    const inFlight = join(cache, "active.mp4");
-    const staleTemp = join(cache, ".tmp-crashed-active.mp4");
+    const inFlight = proxy(cache, "active");
+    const staleTemp = join(cache, `.tmp-${randomUUID()}-${basename(inFlight)}`);
     writeEntry(inFlight, 12, now - 40 * 24 * 60 * 60 * 1000);
     writeEntry(staleTemp, 3, now - 2 * 60 * 60 * 1000);
 
@@ -91,9 +115,27 @@ describe("cleanupProxyCache", () => {
     expect(existsSync(inFlight)).toBe(true);
   });
 
+  it("never removes a file the transcoder did not name, even from an idle cache over budget", () => {
+    const cache = cacheDir();
+    const now = 1_800_000_000_000;
+    const userFiles = [join(cache, "holiday.mp4"), join(cache, ".tmp-notes.mp4")];
+    for (const path of userFiles) writeEntry(path, 4, now - 40 * 24 * 60 * 60 * 1000);
+
+    const result = cleanupProxyCache(cache, {
+      now,
+      maxBytes: 0,
+      maxIdleMs: 1,
+      staleTempMs: 1,
+      minSweepIntervalMs: 0,
+    });
+
+    expect(result.removed).toEqual([]);
+    for (const path of userFiles) expect(existsSync(path)).toBe(true);
+  });
+
   it("rate-limits repeated directory sweeps", () => {
     const cache = cacheDir();
-    const path = join(cache, "entry.mp4");
+    const path = proxy(cache, "entry");
     writeEntry(path, 2, 1_000);
 
     const first = cleanupProxyCache(cache, {
diff --git a/packages/studio-server/src/helpers/proxyCache.ts b/packages/studio-server/src/helpers/proxyCache.ts
index 87cd121bbf..96cd7c7a9f 100644
--- a/packages/studio-server/src/helpers/proxyCache.ts
+++ b/packages/studio-server/src/helpers/proxyCache.ts
@@ -8,6 +8,8 @@ const DEFAULT_MIN_SWEEP_INTERVAL_MS = 5 * 60 * 1000;
 const PROXY_EXTENSIONS: ReadonlySet<string> = new Set(
   Object.values(PROXY_VARIANT_CONFIG).map(({ extension }) => extension),
 );
+const TRANSCODER_PROXY_NAME = /^[0-9a-f]{64}\.\w+$/;
+const TRANSCODER_TEMP_NAME = /^\.tmp-[0-9a-f-]{36}-[0-9a-f]{64}\.\w+$/;
 
 export interface ProxyCacheCleanupOptions {
   maxBytes?: number;
@@ -16,6 +18,7 @@ export interface ProxyCacheCleanupOptions {
   minSweepIntervalMs?: number;
   protectedPaths?: ReadonlySet<string>;
   now?: number;
+  dryRun?: boolean;
 }
 
 export interface ProxyCacheCleanupResult {
@@ -78,9 +81,12 @@ function readCacheInventory(
       modifiedAt: stat.mtimeMs,
       protected: protectedPaths.has(path),
     };
-    if (dirent.name.startsWith(".tmp-")) {
+    if (TRANSCODER_TEMP_NAME.test(dirent.name)) {
       if (now - stat.mtimeMs >= staleTempMs) staleTemps.push(entry);
-    } else if (PROXY_EXTENSIONS.has(extname(dirent.name))) {
+    } else if (
+      TRANSCODER_PROXY_NAME.test(dirent.name) &&
+      PROXY_EXTENSIONS.has(extname(dirent.name))
+    ) {
       entries.push(entry);
     }
   }
@@ -97,21 +103,24 @@ function evictCacheEntries(
   now: number,
   maxIdleMs: number,
   maxBytes: number,
+  dryRun: boolean,
 ): Omit<ProxyCacheCleanupResult, "skipped"> {
   const bytesBefore = entries.reduce((total, entry) => total + entry.size, 0);
   let bytesAfter = bytesBefore;
   const removed: string[] = [];
   const remove = (entry: CacheEntry, countsTowardBudget: boolean): void => {
-    unlinkSync(entry.path);
+    if (!dryRun) unlinkSync(entry.path);
     removed.push(entry.path);
     if (countsTowardBudget) bytesAfter -= entry.size;
   };
 
   for (const entry of staleTemps) remove(entry, false);
+  const kept: CacheEntry[] = [];
   for (const entry of entries) {
     if (!entry.protected && now - entry.modifiedAt >= maxIdleMs) remove(entry, true);
+    else kept.push(entry);
   }
-  for (const entry of entries) {
+  for (const entry of kept) {
     if (bytesAfter <= maxBytes) break;
     if (!entry.protected && existsSync(entry.path)) remove(entry, true);
   }
@@ -145,7 +154,7 @@ export function cleanupProxyCache(
   const protectedPaths = options.protectedPaths ?? new Set<string>();
   const { entries, staleTemps } = readCacheInventory(cacheDir, protectedPaths, now, staleTempMs);
   return {
-    ...evictCacheEntries(entries, staleTemps, now, maxIdleMs, maxBytes),
+    ...evictCacheEntries(entries, staleTemps, now, maxIdleMs, maxBytes, options.dryRun ?? false),
     skipped: false,
   };
 }
diff --git a/packages/studio-server/src/helpers/proxyTranscoder.ts b/packages/studio-server/src/helpers/proxyTranscoder.ts
index 98b440fb9c..85d205e980 100644
--- a/packages/studio-server/src/helpers/proxyTranscoder.ts
+++ b/packages/studio-server/src/helpers/proxyTranscoder.ts
@@ -28,7 +28,7 @@ import { mkdirWithinProject, realpath, realProjectRoot } from "./safePath.js";
 
 export const PROXY_PARAMS_VERSION = "v5";
 
-const CACHE_DIR_NAME = ".transcode-cache";
+export const CACHE_DIR_NAME = ".transcode-cache";
 
 function boundedEnvInteger(name: string, fallback: number, min: number, max: number): number {
   const raw = process.env[name]?.trim();
diff --git a/packages/studio-server/src/index.ts b/packages/studio-server/src/index.ts
index c10c105763..93c1022ad3 100644
--- a/packages/studio-server/src/index.ts
+++ b/packages/studio-server/src/index.ts
@@ -3,6 +3,8 @@ export { createProjectSignature, affectsProjectSignature } from "./helpers/proje
 export { compositionsAffectedBy } from "./helpers/compositionInputs.js";
 export { affectsPreview } from "./helpers/previewReads.js";
 export * from "./history/index.js";
+export { cleanupProxyCache } from "./helpers/proxyCache.js";
+export { CACHE_DIR_NAME as PROXY_CACHE_DIR_NAME } from "./helpers/proxyTranscoder.js";
 export type {
   StudioApiAdapter,
   ResolvedProject,
diff --git a/skills-manifest.json b/skills-manifest.json
index 030fffedab..d2035b767e 100644
--- a/skills-manifest.json
+++ b/skills-manifest.json
@@ -30,7 +30,7 @@
       "files": 7
     },
     "hyperframes-cli": {
-      "hash": "2617903119c32228",
+      "hash": "c1b0b3d02ad38edc",
       "files": 11
     },
     "hyperframes-core": {
diff --git a/skills/hyperframes-cli/SKILL.md b/skills/hyperframes-cli/SKILL.md
index 1a9b7d7072..38fba47ff0 100644
--- a/skills/hyperframes-cli/SKILL.md
+++ b/skills/hyperframes-cli/SKILL.md
@@ -3,7 +3,7 @@ name: hyperframes-cli
 description: >
   Use the HyperFrames CLI development loop: init, add, catalog, capture, lint, check, snapshot,
   compare, grade-compare, preview, play, present, beats, keyframes, single or batch render, publish,
-  cloud, cloudrun, feedback, lambda, doctor, browser, info, upgrade, skills, compositions, timeline, history, docs,
+  cloud, cloudrun, feedback, lambda, doctor, browser, info, upgrade, skills, compositions, timeline, history, clean, docs,
   benchmark, telemetry, transcribe, auth, tts, and remove-background. Also use when diagnosing build
   or render failures. validate, inspect, and layout are deprecated aliases; use check. Covers local,
   HeyGen-hosted cloud, AWS Lambda, and Google Cloud Run rendering.
@@ -100,6 +100,7 @@ Treat tiny unstyled content, canvas-sized icons, missing hero elements, or timel
 
 - Non-TTY mode is automatic and scaffolds the centered blank. Pass `--example` only to start from a named example. Use `--non-interactive` to force flag-only mode on a TTY.
 - Use one `HYPERFRAMES_RUN_ID` for all commands in the same verification loop.
+- When disk is tight, run `npx hyperframes clean` (`--dry-run` to list first); it removes what dead renders left and idle caches that rebuild themselves, never outputs, sources or anything a running render uses. Write QC frames to a temp dir, not the project.
 - Use `--strict`, `--strict-all`, and `--strict-variables` when the corresponding warnings, variables, or CI conditions must gate the render.
 - JSON paths redact the home directory as `$HOME`; do not try to reverse the redaction.
 - When a hosted cloud project approaches or exceeds the 200 MB upload limit, use `cloud render --dry-run --json` and follow the `.hyperframesignore` investigation in `references/cloud.md`. Never ignore an asset merely because it is large.