Add ExecuWhisper macOS dictation example (Parakeet + LFM2.5 formatter)

[seyeong-han]

Fully On-Device Free Dictation App

clean-reformatting.mp4

What you hear in the clip:

"Uh can we, can we move the meeting uh to Friday, actually no, let's let's make it Monday at 10 in the morning."

What gets pasted:

Can we move the meeting to Friday? Actually, no, let's make it Monday at 10 AM in the morning.

execuwhisper-overlay-dictation.mp4

Summary

ExecuWhisper is a native macOS dictation app that runs fully on-device using ExecuTorch. ASR via NVIDIA Parakeet-TDT (Metal backend); a fine-tuned LiquidAI LFM2.5-350M cleans disfluencies, casing, and punctuation (MLX delegate). No cloud, no API keys, no telemetry.

This PR adds the source under execuwhisper/macos/, mirroring the existing voxtral_realtime/macos/ layout.

What's in this diff

• New execuwhisper/macos/ directory:
  • ExecuWhisper/ — Swift app source.
  • ExecuWhisperTests/ — XCTest target.
  • docs/ — demo script, support runbook, release-QA checklist.
  • scripts/ — build.sh, create_dmg.sh, sign_release.sh, verify_*, probe_formatter.py, benchmark_helper.py.
  • project.yml — xcodegen spec (no DEVELOPMENT_TEAM hard-coded; user supplies via env var).
  • README.md, CHANGELOG.md, THIRD_PARTY_NOTICES.md, .gitignore.

Upstream dependencies (in review)

The helper binaries this app embeds live in three PRs against pytorch/executorch that are still in review. Reviewers/users have two paths:

• A. Wait for them to land on pytorch/executorch:main and build everything from a single source checkout.
• B. Use the prebuilt arm64 helpers attached to this PR's GitHub Release and only build the Swift app locally.

PR	What it adds
pytorch/executorch#18861	parakeet_helper (ASR runtime, Metal) + make parakeet-metal
pytorch/executorch#19195	LFM2.5 MLX export pipeline + lfm2_5_350m model class + lfm_2_5-mlx Makefile target
pytorch/executorch#19562	lfm25_formatter_helper (formatter runtime, MLX) + make lfm_2_5_formatter-mlx

Models

• ASR: younghan-meta/Parakeet-TDT-ExecuTorch-Metal
• Formatter: younghan-meta/LFM2.5-350M-ExecuWhisper-Formatter (new dedicated repo for the ExecuWhisper-specific fine-tune; includes fp32 weights, MLX-exported .pte, tokenizer, and full eval reports)

Prebuilt binaries

GitHub Release execuwhisper-v0.1.0 on the fork (until this PR merges) ships:

• lfm25_formatter_helper-arm64-darwin.tar.gz
• parakeet_helper-arm64-darwin.tar.gz
• mlx.metallib
• helpers-arm64-darwin.tar.gz (one-shot bundle of the above)

Helpers are pre-signed with the hardened runtime + disable-library-validation + allow-dyld-environment-variables entitlements. Not redistributing libomp.dylib (third-party LLVM OpenMP) — users obtain via brew install libomp. Not redistributing the .app / .dmg (legal review pending).

Validation

Release-gate eval for the formatter (AMI corpus subset):

Metric	Value	Gate	Status
Forbidden	0.030	≤ 0.10	✅
Coverage	0.874	≥ 0.85	✅
Verdict	RELEASE-READY	—	✅

In-app smoke tests: dictation overlay, hotkey, replacements, snippets, session export, long-input chunking, helper warm reuse — all passing on macOS 14.x and 15.x, MacBook Pro M3 / Mac Studio M2.

Known limitations

• macOS-only; Apple Silicon required (M1+); macOS 14+.
• Three upstream ExecuTorch PRs still in review (linked above).
• Formatter occasionally over-summarizes self-corrections ("actually no — make it tomorrow"); see model card for full eval breakdown.
• 30-word chunker is naive on word boundaries; smarter chunking deferred.

What changed since the previous push of this branch

• Moved from ExecuWhisper/ (top-level) to execuwhisper/macos/ (mirrors voxtral_realtime/macos/ convention).
• Dropped the committed .xcodeproj/; added .gitignore and an xcodegen generate build step.
• Removed hard-coded DEVELOPMENT_TEAM; users supply via env var.
• Sanitized requirements_et-mlx.txt / requirements_et-metal.txt (removed @ file:///Users/younghan/... editable installs; documented pip install -e <executorch_path> step in README).
• Updated HF repo references from younghan-meta/LFM2.5-ExecuTorch-MLX to the new dedicated younghan-meta/LFM2.5-350M-ExecuWhisper-Formatter.
• Removed internal handover docs (FINETUNING_HANDOVER.md, FINETUNING_DATASET_HANDOFF.md).
• Added THIRD_PARTY_NOTICES.md, ASCII architecture diagram, acknowledgements.
• Replaced personal-name test fixture in TextPipelineTests.swift with a generic example.
• Reworded "internal DMG" language across CHANGELOG.md, RELEASE_QA_CHECKLIST.md, and create_dmg.sh.
• Added BSD copyright headers to probe_formatter.py, sign_release.sh, verify_project_settings.sh, verify_release.sh.
• Eval results published to the HF model card under eval/.

Reviewer guidance

• Focus on: the Swift app (ExecuWhisper/Services/, ExecuWhisper/Views/), the build wiring (project.yml, scripts/build.sh), and the README's prebuilt-vs-source story.
• Auto-tested: xcodebuild -scheme ExecuWhisper test exercises the formatter prompt builder, replacement pipeline, session compatibility, and helper bridge reuse.
• Out of scope for this PR: Windows/Linux ports, DMG distribution (legal review pending), CI for native macOS apps in this repo (no precedent).