fix(review): worker-thread HEIC conversion with bomb guard, concurrency cap, and magic-byte routing (PR #151)

- Event-loop blockage: HEIC decode/encode (CPU-synchronous libheif WASM +
  jpeg-js) now runs in a per-conversion worker_threads Worker
  (src/web/heic-jpeg-worker.ts, spawned by heic-jpeg-converter.ts) with
  resourceLimits and a 30s hard timeout that terminates the worker —
  verified end-to-end under tsx and against compiled dist/ output with a
  real iPhone HEIC (event-loop max stall 52ms during conversion).
- No server-side concurrency cap: conversions now acquire a slot from the
  existing global runWithConversionLimit() pool (document-conversion-limiter),
  bounding peak decode memory/CPU across simultaneous uploads.
- Decompression bomb: header-declared dimensions are read via heic-decode's
  allocation-free `.all` path and rejected above 64MP BEFORE decode() can
  allocate width*height*4 bytes (a <300-byte crafted file can declare
  30000x30000 = 3.6GB). Regression-tested with a crafted ISOBMFF fixture
  against the real heic-decode WASM (test/heic-jpeg-core.test.ts).
- Mislabeled HEIC (documented Android/MIUI case): conversion now routes on
  ftyp magic-byte sniff of the raw buffer regardless of declared
  ext/Content-Type, so a HEIF uploaded as image/jpeg converts instead of
  415ing; the magic-mismatch 415 only fires for genuinely unrecognized bytes.
- Brand allowlist narrowed to what heic-decode's isHeic() accepts
  (heim/heis/hevm/hevs dropped — they could only ever fail conversion).
- Converted-output size: the JPEG result is checked against
  MAX_PASTE_IMAGE_BYTES (jpeg-js can inflate a within-limit HEIC past the cap).
- Deps: heic-convert replaced with its underlying heic-decode + jpeg-js
  (the wrapper could not expose the pre-decode dimension check); lockfile
  synced, drops pngjs.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

package-lock.json

@@ -28,7 +28,8 @@
         "chokidar": "^3.6.0",
         "commander": "^12.1.0",
         "fastify": "^5.8.5",
-        "heic-convert": "^2.1.0",
+        "heic-decode": "^2.1.0",
+        "jpeg-js": "^0.4.4",
         "node-pty": "^1.1.0",
         "qrcode": "^1.5.4",
         "uuid": "^14.0.0",
@@ -7024,29 +7025,6 @@
         "node": ">= 0.4"
       }
     },
-    "node_modules/heic-convert": {
-      "version": "2.1.0",
-      "resolved": "https://registry.npmjs.org/heic-convert/-/heic-convert-2.1.0.tgz",
-      "integrity": "sha512-1qDuRvEHifTVAj3pFIgkqGgJIr0M3X7cxEPjEp0oG4mo8GFjq99DpCo8Eg3kg17Cy0MTjxpFdoBHOatj7ZVKtg==",
-      "license": "ISC",
-      "dependencies": {
-        "heic-decode": "^2.0.0",
-        "jpeg-js": "^0.4.4",
-        "pngjs": "^6.0.0"
-      },
-      "engines": {
-        "node": ">=12.0.0"
-      }
-    },
-    "node_modules/heic-convert/node_modules/pngjs": {
-      "version": "6.0.0",
-      "resolved": "https://registry.npmjs.org/pngjs/-/pngjs-6.0.0.tgz",
-      "integrity": "sha512-TRzzuFRRmEoSW/p1KVAmiOgPco2Irlah+bGFCeNfJXxxYGwSw7YwAOAcd7X28K/m5bjBWKsC29KyoMfHbypayg==",
-      "license": "MIT",
-      "engines": {
-        "node": ">=12.13.0"
-      }
-    },
     "node_modules/heic-decode": {
       "version": "2.1.0",
       "resolved": "https://registry.npmjs.org/heic-decode/-/heic-decode-2.1.0.tgz",

package.json

@@ -69,7 +69,8 @@
     "chokidar": "^3.6.0",
     "commander": "^12.1.0",
     "fastify": "^5.8.5",
-    "heic-convert": "^2.1.0",
+    "heic-decode": "^2.1.0",
+    "jpeg-js": "^0.4.4",
     "node-pty": "^1.1.0",
     "qrcode": "^1.5.4",
     "uuid": "^14.0.0",

src/types/heic-convert.d.ts

@@ -1,9 +0,0 @@
-declare module 'heic-convert' {
-  export interface ConvertOptions {
-    buffer: Buffer;
-    format: 'JPEG' | 'PNG';
-    quality?: number;
-  }
-
-  export default function convert(options: ConvertOptions): Promise<Buffer | Uint8Array | ArrayBuffer>;
-}

src/types/heic-decode.d.ts

@@ -0,0 +1,24 @@
+declare module 'heic-decode' {
+  export interface DecodedHeicImage {
+    width: number;
+    height: number;
+    data: Uint8ClampedArray;
+  }
+
+  /** Handle exposing header-declared dimensions WITHOUT decoding pixels. */
+  export interface HeicImageHandle {
+    width: number;
+    height: number;
+    decode(): Promise<DecodedHeicImage>;
+  }
+
+  export type HeicImageHandles = HeicImageHandle[] & { dispose(): void };
+
+  interface HeicDecode {
+    (input: { buffer: Buffer | Uint8Array }): Promise<DecodedHeicImage>;
+    all(input: { buffer: Buffer | Uint8Array }): Promise<HeicImageHandles>;
+  }
+
+  const decode: HeicDecode;
+  export default decode;
+}

src/web/heic-jpeg-converter.ts

@@ -0,0 +1,82 @@
+/**
+ * @fileoverview Main-thread wrapper for HEIC/HEIF → JPEG conversion.
+ *
+ * The actual decode/encode (`heic-jpeg-worker.ts`) is CPU-synchronous WASM + JS,
+ * so it runs in a dedicated `worker_threads` Worker per conversion — never on
+ * the event loop that serves every session's SSE/PTY/WS traffic. On top of
+ * the worker isolation this wrapper enforces:
+ *  - the global converter concurrency cap (`runWithConversionLimit`, shared
+ *    with the pdftoppm/soffice document converters) so N simultaneous uploads
+ *    can't pin N cores / N × 256MB decode buffers at once;
+ *  - a hard timeout that terminates the worker (a wedged WASM decode can't be
+ *    cancelled cooperatively);
+ *  - the paste-image size cap on the *output* — jpeg-js is a far less
+ *    efficient encoder than HEVC, so a within-limit HEIC can inflate past
+ *    MAX_PASTE_IMAGE_BYTES.
+ */
+
+import { Worker } from 'node:worker_threads';
+import { runWithConversionLimit } from '../document-conversion-limiter.js';
+import { MAX_PASTE_IMAGE_BYTES } from '../config/buffer-limits.js';
+import { HEIC_JPEG_QUALITY, type HeicWorkerInput, type HeicWorkerResult } from './heic-jpeg-worker.js';
+
+/** Hard cap on a single conversion; the worker is terminated when it fires. */
+export const HEIC_CONVERSION_TIMEOUT_MS = 30_000;
+
+// V8-heap guardrails for the conversion worker — defense in depth only: large
+// TypedArray/WASM backing stores are external to the V8 heap, so the real
+// memory bound is the 64MP dimension pre-check in heic-jpeg-worker.ts.
+const WORKER_RESOURCE_LIMITS = { maxOldGenerationSizeMb: 1024, maxYoungGenerationSizeMb: 128, stackSizeMb: 8 };
+
+function workerUrl(): URL {
+  // Compiled installs run the tsc-emitted .js sibling in dist/; dev under tsx
+  // runs the .ts source directly (tsx's loader propagates to worker threads).
+  const file = import.meta.url.endsWith('.ts') ? './heic-jpeg-worker.ts' : './heic-jpeg-worker.js';
+  return new URL(file, import.meta.url);
+}
+
+/**
+ * Convert HEIC/HEIF bytes to JPEG bytes off-thread. Rejects on invalid input,
+ * over-limit dimensions, oversized output, timeout, or worker failure.
+ */
+export async function convertHeicToJpeg(imageBytes: Buffer): Promise<Buffer> {
+  return runWithConversionLimit(
+    () =>
+      new Promise<Buffer>((resolve, reject) => {
+        const worker = new Worker(workerUrl(), {
+          workerData: { heicInput: imageBytes, quality: HEIC_JPEG_QUALITY } satisfies HeicWorkerInput,
+          resourceLimits: WORKER_RESOURCE_LIMITS,
+        });
+        let settled = false;
+        const settle = (fn: () => void): void => {
+          if (settled) return;
+          settled = true;
+          clearTimeout(timer);
+          fn();
+          void worker.terminate();
+        };
+        const timer = setTimeout(() => {
+          settle(() => reject(new Error(`HEIC conversion timed out after ${HEIC_CONVERSION_TIMEOUT_MS}ms`)));
+        }, HEIC_CONVERSION_TIMEOUT_MS);
+        worker.on('message', (msg: HeicWorkerResult) => {
+          settle(() => {
+            if (!msg.ok) {
+              reject(new Error(msg.error));
+              return;
+            }
+            const out = Buffer.from(msg.data.buffer, msg.data.byteOffset, msg.data.byteLength);
+            if (out.length > MAX_PASTE_IMAGE_BYTES) {
+              const maxMb = Math.round(MAX_PASTE_IMAGE_BYTES / (1024 * 1024));
+              reject(new Error(`converted JPEG (${out.length} bytes) exceeds the ${maxMb}MB upload limit`));
+              return;
+            }
+            resolve(out);
+          });
+        });
+        worker.on('error', (err) => settle(() => reject(err)));
+        worker.on('exit', (code) => {
+          settle(() => reject(new Error(`HEIC conversion worker exited unexpectedly (code ${code})`)));
+        });
+      })
+  );
+}

src/web/heic-jpeg-worker.ts

@@ -0,0 +1,93 @@
+/**
+ * @fileoverview HEIC/HEIF → JPEG conversion core + worker-thread entry.
+ *
+ * Spawned per conversion by `heic-jpeg-converter.ts` so the CPU-synchronous
+ * libheif WASM decode + jpeg-js encode never run on the server's main thread
+ * (on the event loop they would freeze every session's SSE/PTY/WS handling
+ * for seconds per photo). Input arrives via `workerData`; the result (or
+ * error message) is posted back as a single message and the thread exits.
+ *
+ * The conversion logic lives in this same file (exported, guarded bootstrap)
+ * rather than a sibling module: the worker runs from `.ts` source under tsx
+ * in dev, where relative `.js` imports don't resolve inside worker threads —
+ * only `node:` builtins are imported at top level. Unit tests import
+ * `convertHeicBufferToJpeg` directly; the bootstrap only runs when spawned
+ * with our `workerData` shape.
+ *
+ * Decompression-bomb guard: heic-decode's `.all` path exposes the
+ * header-declared {width, height} per image WITHOUT decoding pixels, while
+ * its plain decode path allocates `width * height * 4` bytes straight from
+ * those header values — a <1KB crafted file declaring 30000×30000 would
+ * demand a 3.6GB allocation. We reject anything above MAX_HEIC_DECODE_PIXELS
+ * before calling `decode()`.
+ */
+
+import { parentPort, workerData } from 'node:worker_threads';
+
+/** Max header-declared pixel count we will decode (64MP ≈ 256MB RGBA). */
+export const MAX_HEIC_DECODE_PIXELS = 64_000_000;
+
+/** JPEG quality used for converted HEIC uploads (matches heic-convert's default). */
+export const HEIC_JPEG_QUALITY = 0.92;
+
+export interface HeicWorkerInput {
+  heicInput: Uint8Array;
+  quality: number;
+}
+
+export type HeicWorkerResult = { ok: true; data: Uint8Array } | { ok: false; error: string };
+
+/**
+ * Convert HEIC/HEIF bytes to JPEG bytes. Throws on non-HEIC input, empty
+ * containers, over-limit dimensions, and non-JPEG encoder output.
+ */
+export async function convertHeicBufferToJpeg(input: Uint8Array, quality: number = HEIC_JPEG_QUALITY): Promise<Buffer> {
+  const { default: decode } = await import('heic-decode');
+  const buffer = Buffer.isBuffer(input) ? input : Buffer.from(input.buffer, input.byteOffset, input.byteLength);
+  const images = await decode.all({ buffer });
+  try {
+    if (images.length === 0) throw new Error('no image found in HEIC container');
+    const { width, height } = images[0];
+    if (
+      !Number.isSafeInteger(width) ||
+      !Number.isSafeInteger(height) ||
+      width <= 0 ||
+      height <= 0 ||
+      width * height > MAX_HEIC_DECODE_PIXELS
+    ) {
+      throw new Error(
+        `HEIC dimensions ${width}x${height} exceed the ${Math.floor(MAX_HEIC_DECODE_PIXELS / 1_000_000)}MP decode limit`
+      );
+    }
+    const decoded = await images[0].decode();
+    const { encode } = await import('jpeg-js');
+    // Same output path as heic-convert's JPEG format (jpeg-js at quality*100).
+    const jpeg = encode(
+      { data: decoded.data, width: decoded.width, height: decoded.height },
+      Math.floor(quality * 100)
+    ).data;
+    const jpegBytes = Buffer.isBuffer(jpeg) ? jpeg : Buffer.from(jpeg);
+    if (jpegBytes.length < 3 || jpegBytes[0] !== 0xff || jpegBytes[1] !== 0xd8 || jpegBytes[2] !== 0xff) {
+      throw new Error('HEIC conversion did not produce JPEG bytes');
+    }
+    return jpegBytes;
+  } finally {
+    images.dispose();
+  }
+}
+
+// ── Worker bootstrap ──────────────────────────────────────────────────────
+// Runs only when spawned by heic-jpeg-converter.ts: requires a parent port
+// AND our exact workerData shape, so importing this module from the main
+// thread (or a test runner's own worker pool) stays inert.
+const request = workerData as HeicWorkerInput | null | undefined;
+if (parentPort && request && request.heicInput instanceof Uint8Array && typeof request.quality === 'number') {
+  const port = parentPort;
+  try {
+    const jpegBytes = await convertHeicBufferToJpeg(request.heicInput, request.quality);
+    port.postMessage({ ok: true, data: jpegBytes } satisfies HeicWorkerResult);
+  } catch (err: unknown) {
+    const error = err instanceof Error ? err.message : String(err);
+    port.postMessage({ ok: false, error } satisfies HeicWorkerResult);
+  }
+}

src/web/routes/session-routes.ts

@@ -54,6 +54,7 @@ import {
 } from '../../hooks-config.js';
 import { generateClaudeMd } from '../../templates/claude-md.js';
 import { imageWatcher } from '../../image-watcher.js';
+import { convertHeicToJpeg } from '../heic-jpeg-converter.js';
 import { getLifecycleLog } from '../../session-lifecycle-log.js';
 import type { SessionPort, EventPort, ConfigPort, InfraPort, AuthPort } from '../ports/index.js';
 import { MAX_CONCURRENT_SESSIONS } from '../../config/map-limits.js';
@@ -191,30 +192,18 @@ export function imageMagicMatchesExt(data: Buffer, ext: string): boolean {
       return data[0] === 0x42 && data[1] === 0x4d;
     case '.heic':
     case '.heif': {
-      // ISO Base Media File Format: size + "ftyp" + major brand.
+      // ISO Base Media File Format: size + "ftyp" + major brand. The brand
+      // list matches heic-decode's own isHeic() — accepting more brands here
+      // would only route bytes into a conversion that always throws.
       if (u32be(4) !== 0x66747970) return false;
       const brand = data.subarray(8, 12).toString('ascii');
-      return ['heic', 'heix', 'hevc', 'hevx', 'heim', 'heis', 'hevm', 'hevs', 'mif1', 'msf1'].includes(brand);
+      return ['heic', 'heix', 'hevc', 'hevx', 'mif1', 'msf1'].includes(brand);
     }
     default:
       return false;
   }
 }
 
-async function convertHeicToJpeg(imageBytes: Buffer): Promise<Buffer> {
-  const { default: convert } = await import('heic-convert');
-  const converted = await convert({ buffer: imageBytes, format: 'JPEG', quality: 0.92 });
-  const jpegBytes = Buffer.isBuffer(converted)
-    ? converted
-    : converted instanceof ArrayBuffer
-      ? Buffer.from(converted)
-      : Buffer.from(converted.buffer, converted.byteOffset, converted.byteLength);
-  if (!imageMagicMatchesExt(jpegBytes, '.jpg')) {
-    throw new Error('HEIC conversion did not produce JPEG bytes');
-  }
-  return jpegBytes;
-}
-
 // Per-(IP, sessionId) token bucket for paste-image. 30 requests/minute.
 // Bucket map entries are pruned when they drift > 1h stale to bound memory
 // against a flood of unique IP keys.
@@ -1889,22 +1878,12 @@ export function registerSessionRoutes(
       );
     }
 
-    // Sniff actual bytes — filename and Content-Type are both attacker-supplied.
+    // Route HEIC on the raw bytes, NOT the declared ext/mime: on some Android
-    // Polyglot HTML/PNG would otherwise pass and serve back with image/png MIME.
+    // galleries (e.g. MIUI) a HEIF comes back mislabeled as image/jpeg, and
-    if (!imageMagicMatchesExt(imageBytes, ext)) {
+    // browsers that cannot decode HEIF upload the original file as-is — so a
-      // Diagnostic: on some Android galleries (e.g. MIUI) a WebP/HEIF is
+    // HEIC payload can arrive under any declared type. Filename and
-      // mislabeled as image/jpeg, so the declared ext passes the allowlist but
+    // Content-Type are attacker-supplied anyway; only the bytes are trusted.
-      // the magic bytes do not. Log the real header so format mismatches can be
+    if (imageMagicMatchesExt(imageBytes, '.heic')) {
-      // pinned down without a reproduce-and-guess loop. The client now
-      // re-encodes images to JPEG/PNG before upload, so this should be rare.
-      console.warn(
-        `[paste-image] magic mismatch: filename=${JSON.stringify(part.filename)} mime=${JSON.stringify(part.mimetype)} declaredExt=${ext} magic=${imageBytes.subarray(0, 12).toString('hex')}`
-      );
-      reply.code(415);
-      return createErrorResponse(ApiErrorCode.INVALID_INPUT, `Image bytes do not match declared type ${ext}`);
-    }
-
-    if (ext === '.heic' || ext === '.heif') {
       try {
         imageBytes = await convertHeicToJpeg(imageBytes);
         ext = '.jpg';
@@ -1915,6 +1894,16 @@ export function registerSessionRoutes(
         reply.code(415);
         return createErrorResponse(ApiErrorCode.INVALID_INPUT, 'Could not convert HEIC image to JPEG');
       }
+    } else if (!imageMagicMatchesExt(imageBytes, ext)) {
+      // Sniff actual bytes — a polyglot HTML/PNG would otherwise pass and
+      // serve back with image/png MIME. Log the real header so format
+      // mismatches can be pinned down without a reproduce-and-guess loop. The
+      // client re-encodes images to JPEG/PNG before upload, so this is rare.
+      console.warn(
+        `[paste-image] magic mismatch: filename=${JSON.stringify(part.filename)} mime=${JSON.stringify(part.mimetype)} declaredExt=${ext} magic=${imageBytes.subarray(0, 12).toString('hex')}`
+      );
+      reply.code(415);
+      return createErrorResponse(ApiErrorCode.INVALID_INPUT, `Image bytes do not match declared type ${ext}`);
     }
 
     // Save to {workingDir}/.claude-images/

test/heic-jpeg-core.test.ts

@@ -0,0 +1,125 @@
+/**
+ * @fileoverview Tests for the HEIC → JPEG conversion core (heic-jpeg-worker.ts).
+ *
+ * Exercises the REAL heic-decode WASM parse path (no mocks) for the
+ * decompression-bomb guard: a crafted <300-byte HEIC can declare arbitrary
+ * dimensions in its `ispe` box, and heic-decode's plain decode path allocates
+ * `width * height * 4` bytes straight from those header values (30000×30000 →
+ * a 3.6GB allocation). The guard must reject via the allocation-free `.all`
+ * dimension read BEFORE decode().
+ *
+ * Port: N/A (pure module test, no server).
+ */
+
+import { describe, it, expect, vi } from 'vitest';
+import { convertHeicBufferToJpeg, MAX_HEIC_DECODE_PIXELS } from '../src/web/heic-jpeg-worker.js';
+
+// ── Minimal ISOBMFF/HEIF builder — just enough boxes (ftyp/meta/hdlr/pitm/
+// iloc/iinf/iprp[hvcC+ispe]/mdat) for libheif to parse the image handle and
+// report the ispe-declared dimensions. There is no real HEVC bitstream, so
+// pixel decode of these files always fails — which is the point: the guard
+// must fire before any decode is attempted.
+
+function box(type: string, ...payloads: (Buffer | string)[]): Buffer {
+  const payload = Buffer.concat(payloads.map((p) => (Buffer.isBuffer(p) ? p : Buffer.from(p))));
+  const header = Buffer.alloc(8);
+  header.writeUInt32BE(8 + payload.length, 0);
+  header.write(type, 4, 'ascii');
+  return Buffer.concat([header, payload]);
+}
+
+function fullbox(type: string, version: number, flags: number, ...payloads: (Buffer | string)[]): Buffer {
+  const vf = Buffer.alloc(4);
+  vf.writeUInt32BE((version << 24) | flags, 0);
+  return box(type, vf, ...payloads);
+}
+
+function u16(n: number): Buffer {
+  const b = Buffer.alloc(2);
+  b.writeUInt16BE(n, 0);
+  return b;
+}
+
+function u32(n: number): Buffer {
+  const b = Buffer.alloc(4);
+  b.writeUInt32BE(n, 0);
+  return b;
+}
+
+/** Craft a HEIC container whose header declares `width`×`height`. */
+function craftHeic(width: number, height: number): Buffer {
+  const ftyp = box('ftyp', 'heic', u32(0), 'mif1heic');
+  const hdlr = fullbox('hdlr', 0, 0, u32(0), 'pict', u32(0), u32(0), u32(0), Buffer.from([0]));
+  const pitm = fullbox('pitm', 0, 0, u16(1));
+  const infe = fullbox('infe', 2, 0, u16(1), u16(0), 'hvc1', Buffer.from([0]));
+  const iinf = fullbox('iinf', 0, 0, u16(1), infe);
+  const ispe = fullbox('ispe', 0, 0, u32(width), u32(height));
+  // Minimal HEVCDecoderConfigurationRecord (23 bytes, zero parameter-set arrays).
+  const hvcC = box(
+    'hvcC',
+    Buffer.from([
+      0x01, 0x01, 0x60, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x5d, 0xf0, 0x00, 0xfc, 0xfd, 0xf8, 0xf8, 0x00,
+      0x00, 0x03, 0x00,
+    ]),
+    Buffer.from([0x00])
+  );
+  const ipco = box('ipco', hvcC, ispe);
+  const ipma = fullbox('ipma', 0, 0, u32(1), u16(1), Buffer.from([2]), Buffer.from([0x81, 0x02]));
+  const iprp = box('iprp', ipco, ipma);
+  // iloc v0: offset_size=4, length_size=4, base_offset_size=0; one extent in mdat.
+  const ilocItem = Buffer.concat([u16(1), u16(0), u16(1), u32(0), u32(16)]);
+  const iloc = fullbox('iloc', 0, 0, Buffer.from([0x44, 0x00]), u16(1), ilocItem);
+  const meta = fullbox('meta', 0, 0, hdlr, pitm, iloc, iinf, iprp);
+  const mdat = box('mdat', Buffer.alloc(16));
+  return Buffer.concat([ftyp, meta, mdat]);
+}
+
+describe('heic-jpeg-core', () => {
+  it('rejects a crafted bomb header (30000×30000 declared, 3.6GB decode) before decoding', async () => {
+    const bomb = craftHeic(30000, 30000);
+    expect(bomb.length).toBeLessThan(1024); // tiny input, huge declared output
+    await expect(convertHeicBufferToJpeg(bomb)).rejects.toThrow(/30000x30000 exceed the 64MP decode limit/);
+  });
+
+  it('rejects dimensions just over the cap', async () => {
+    // 8000×8001 = 64,008,000 px — barely over MAX_HEIC_DECODE_PIXELS (64MP).
+    expect(8000 * 8001).toBeGreaterThan(MAX_HEIC_DECODE_PIXELS);
+    await expect(convertHeicBufferToJpeg(craftHeic(8000, 8001))).rejects.toThrow(/decode limit/);
+  });
+
+  it('lets dimensions under the cap through the guard (failure, if any, comes from pixel decode)', async () => {
+    // The crafted file has no real HEVC bitstream, so decode fails — but NOT
+    // with the dimension-limit error, proving the guard ran and passed.
+    await expect(convertHeicBufferToJpeg(craftHeic(100, 100))).rejects.toThrow(/^(?!.*decode limit).*$/);
+  });
+
+  it('rejects non-HEIC bytes', async () => {
+    await expect(convertHeicBufferToJpeg(Buffer.from('this is definitely not a HEIC image'))).rejects.toThrow(
+      /not a HEIC image/i
+    );
+  });
+
+  it('encodes decoded RGBA into JPEG bytes with valid magic (heic-decode mocked, real jpeg-js)', async () => {
+    const dispose = vi.fn();
+    const handle = {
+      width: 2,
+      height: 2,
+      decode: async () => ({ width: 2, height: 2, data: new Uint8ClampedArray(16).fill(128) }),
+    };
+    vi.doMock('heic-decode', () => {
+      const decode = Object.assign(async () => handle.decode(), {
+        all: async () => Object.assign([handle], { dispose }),
+      });
+      return { default: decode };
+    });
+    try {
+      const jpeg = await convertHeicBufferToJpeg(Buffer.from('mock input'));
+      expect(jpeg[0]).toBe(0xff);
+      expect(jpeg[1]).toBe(0xd8);
+      expect(jpeg[2]).toBe(0xff);
+      expect(dispose).toHaveBeenCalledTimes(1);
+    } finally {
+      vi.doUnmock('heic-decode');
+    }
+  });
+});

test/routes/session-routes.test.ts

@@ -26,12 +26,15 @@ import { ApiErrorCode, httpStatusForErrorCode } from '../../src/types.js';
 
 // Mock execFile so the send-key route's `tmux` invocation is observable (not run for real).
 const { execFile } = vi.hoisted(() => ({ execFile: vi.fn() }));
+// The real converter spawns a worker thread (TS worker file — not loadable
+// under vitest); the conversion pipeline itself is covered by
+// test/heic-jpeg-core.test.ts against the real heic-decode WASM.
 const heicConvert = vi.hoisted(() => vi.fn(async () => Buffer.from('ffd8ffe000104a4649460001', 'hex')));
 vi.mock('node:child_process', async (orig) => {
   const actual = await orig<typeof import('node:child_process')>();
   return { ...actual, execFile };
 });
-vi.mock('heic-convert', () => ({ default: heicConvert }));
+vi.mock('../../src/web/heic-jpeg-converter.js', () => ({ convertHeicToJpeg: heicConvert }));
 
 import { registerSessionRoutes } from '../../src/web/routes/session-routes.js';
 
@@ -170,7 +173,81 @@ describe('session-routes', () => {
       const body = JSON.parse(res.body);
       expect(body.success).toBe(true);
       expect(body.data.path).toMatch(/\/\.claude-images\/paste-\d+-[a-f0-9]{8}\.jpg$/);
-      expect(heicConvert).toHaveBeenCalledWith({ buffer: heic, format: 'JPEG', quality: 0.92 });
+      expect(heicConvert).toHaveBeenCalledWith(heic);
+    });
+
+    it('converts mislabeled HEIC (declared image/jpeg, HEIF bytes — the MIUI/Android case) via magic sniff', async () => {
+      const workDir = await mkdtemp(join(tmpdir(), 'codeman-heic-mislabel-'));
+      harness.ctx._session.workingDir = workDir;
+      heicConvert.mockClear();
+
+      const boundary = 'codeman-test-boundary';
+      // ftyp brand mif1 — HEIF bytes hiding under a JPEG filename + MIME.
+      const heic = Buffer.from('000000346674797061696631000000006d69663168656963', 'hex');
+      heic.write('mif1', 8, 'ascii'); // major brand
+      const res = await harness.app.inject({
+        method: 'POST',
+        url: `/api/sessions/${harness.ctx._sessionId}/paste-image`,
+        headers: {
+          host: 'codeman.test',
+          origin: 'http://codeman.test',
+          'content-type': `multipart/form-data; boundary=${boundary}`,
+        },
+        payload: imageUploadBody(boundary, 'IMG_2001.jpg', 'image/jpeg', heic),
+      });
+
+      await rm(workDir, { recursive: true });
+
+      expect(res.statusCode).toBe(200);
+      const body = JSON.parse(res.body);
+      expect(body.success).toBe(true);
+      expect(body.data.path).toMatch(/\/\.claude-images\/paste-\d+-[a-f0-9]{8}\.jpg$/);
+      expect(heicConvert).toHaveBeenCalledWith(heic);
+    });
+
+    it('returns 415 with the error envelope when HEIC conversion fails', async () => {
+      heicConvert.mockClear();
+      heicConvert.mockRejectedValueOnce(new Error('HEIC dimensions 30000x30000 exceed the 64MP decode limit'));
+
+      const boundary = 'codeman-test-boundary';
+      const heic = Buffer.from('00000034667479706865696300000000', 'hex');
+      const res = await harness.app.inject({
+        method: 'POST',
+        url: `/api/sessions/${harness.ctx._sessionId}/paste-image`,
+        headers: {
+          host: 'codeman.test',
+          origin: 'http://codeman.test',
+          'content-type': `multipart/form-data; boundary=${boundary}`,
+        },
+        payload: imageUploadBody(boundary, 'IMG_4997.HEIC', 'image/heic', heic),
+      });
+
+      expect(res.statusCode).toBe(415);
+      const body = JSON.parse(res.body);
+      expect(body.success).toBe(false);
+      expect(body.errorCode).toBe('INVALID_INPUT');
+      expect(body.error).toMatch(/HEIC/);
+    });
+
+    it('rejects ftyp brands heic-decode cannot convert (e.g. heim) without invoking the converter', async () => {
+      heicConvert.mockClear();
+
+      const boundary = 'codeman-test-boundary';
+      const heim = Buffer.from('00000034667479706865696d00000000', 'hex');
+      const res = await harness.app.inject({
+        method: 'POST',
+        url: `/api/sessions/${harness.ctx._sessionId}/paste-image`,
+        headers: {
+          host: 'codeman.test',
+          origin: 'http://codeman.test',
+          'content-type': `multipart/form-data; boundary=${boundary}`,
+        },
+        payload: imageUploadBody(boundary, 'IMG_4998.HEIC', 'image/heic', heim),
+      });
+
+      expect(res.statusCode).toBe(415);
+      expect(JSON.parse(res.body).success).toBe(false);
+      expect(heicConvert).not.toHaveBeenCalled();
     });
   });