Ffmpeg Kit macOS Codesign Crash

What it does

When your agent uses it

• MacOS app builds successfully but crashes immediately on launch
• Crash log shows Library not loaded: libfontconfig.1.dylib
• Similar homebrew library
• Error mentions code signature not valid for use in process with different Team IDs

Example prompts

• “Library not loaded: libfontconfig.1.dylib”
• “code signature not valid for use in process”
• “different Team IDs”
• “/ffmpeg-kit-macos-codesign-crash”

Workflow steps

3 steps, taken from the first numbered list in SKILL.md.

1. 1flutter run -d macos should launch the app without crashing
2. 2Video encoding/decoding operations should work normally
3. 3iOS builds continue to work (they weren't affected)

What it can do on your machine

Read from SKILL.md and the folder at commit 6487b05. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  Shell commands in SKILL.md call:

  • flutter

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  Links to these hosts (documentation or services it may open):

  • pub.dev
  • developer.apple.com

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Ffmpeg Kit macOS Codesign Crash loads about 1.1k tokens when it runs. Until then it costs about 142 tokens; SKILL.md has 350 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~142

When it runs · the whole SKILL.md, loaded when a task matches

~1.1k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from divinevideo/divine-mobile at commit 6487b05, republished under its MPL-2.0 licence (© divinevideo). 350 words, ~1,142 tokens.

name

ffmpeg-kit-macos-codesign-crash

description

Fix Flutter macOS app crash at launch due to FFmpeg Kit library loading failure. Use when: (1) macOS app builds successfully but crashes immediately on launch, (2) Crash log shows "Library not loaded: libfontconfig.1.dylib" or similar homebrew library, (3) Error mentions "code signature not valid for use in process" with "different Team IDs", (4) Using ffmpeg_kit_flutter_new (Full GPL variant). The Full GPL variant has external dependencies on homebrew libraries that fail macOS code signing. Switch to ffmpeg_kit_flutter_new_min.

author

Claude Code

version

1.0.0

date

2025-01-25

# Before
ffmpeg_kit_flutter_new: ^3.2.0

# After
ffmpeg_kit_flutter_new_min: ^3.1.0

// Before
import 'package:ffmpeg_kit_flutter_new/ffmpeg_kit.dart';
import 'package:ffmpeg_kit_flutter_new/ffprobe_kit.dart';
import 'package:ffmpeg_kit_flutter_new/return_code.dart';

// After
import 'package:ffmpeg_kit_flutter_new_min/ffmpeg_kit.dart';
import 'package:ffmpeg_kit_flutter_new_min/ffprobe_kit.dart';
import 'package:ffmpeg_kit_flutter_new_min/return_code.dart';

flutter clean
rm -f macos/Podfile.lock
flutter pub get
flutter run -d macos

grep -r "ffmpeg_kit_flutter_new" lib/ --include="*.dart" -l

find lib -name "*.dart" -exec sed -i '' \
  's/ffmpeg_kit_flutter_new/ffmpeg_kit_flutter_new_min/g' {} \;

© divinevideo, MPL-2.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in .agents/skills/ffmpeg-kit-macos-codesign-crash of divinevideo/divine-mobile.

Open the folder on GitHubat commit 6487b05