pi-fast-apply

Morph integration package for Pi, starting with a Pi-native Fast Apply extension surface.

Status

pi-fast-apply now ships a Pi-native fast_apply tool backed by the official @morphllm/morphsdk Fast Apply API.

Implemented and verified in this repo:

• native fast_apply tool registration in extensions/index.ts
• Pi-owned path resolution, file reads/writes, and withFileMutationQueue() protection
• dry-run support with preview details (udiff, mergedCode, change counts)
• real SDK-backed write path using Morph API key
• Pi-native auth management with /morph-login, /morph-logout, and /morph-status commands
• manual validation against a temporary real file with both dry-run and real-write success

Not implemented yet:

• WarpGrep Pi-native tools
• Compact lifecycle integration
• richer custom TUI rendering beyond the default text result

Intended package scope

pi-fast-apply is intended to become the Pi-native home for Morph-backed capabilities such as:

• Fast Apply editing via a native fast_apply tool
• future WarpGrep local and GitHub search tools
• future Morph Compact lifecycle integration when Pi hook strategy is ready

The package should keep Pi in control of tool registration, path resolution, queueing, and user-facing UX instead of treating MCP as the primary native path.

Package shape

{
  "pi": {
    "extensions": ["./extensions"],
    "image": "https://raw.githubusercontent.com/victor-software-house/pi-fast-apply/main/assets/preview.png"
  }
}

Requirements

A Morph API key is required to use fast_apply. Two configuration paths are supported:

1. Pi auth storage (recommended) — run /morph-login <api-key> inside Pi to store the key in ~/.pi/agent/auth.json
2. Environment variable — set MORPH_API_KEY in the shell, .env, or via a secret manager like fnox

Resolution priority: Pi auth storage is checked first. If no key is found there, the MORPH_API_KEY environment variable is used as a fallback.

Auth commands

Command	Description
/morph-login <key>	Store a Morph API key in Pi auth storage
/morph-logout	Remove stored Morph credentials from Pi auth storage
/morph-status	Show current auth source, API base URL, and timeout

Additional environment variables

• MORPH_API_URL — override the default Morph base URL (https://api.morphllm.com)
• MORPH_EDIT_TIMEOUT_MS — override the default 60s timeout

Auth security trade-offs

Pi's auth.json is stored with 0600 file permissions and uses file locking for safe concurrent access. This is consistent with how Pi stores credentials for all providers (Anthropic, OpenAI, etc.). For stronger at-rest encryption, environment-variable injection through fnox, age-encrypted secrets, or a system keychain remains a valid alternative — use MORPH_API_KEY via your preferred secret manager instead of /morph-login.

Tool contract

fast_apply is meant for existing files where exact string replacement would be brittle.

Parameters:

• path — relative or absolute path to an existing file
• instruction — first-person change description
• codeEdit — partial edit using // ... existing code ... markers
• dryRun — preview without writing the file

Behavior:

• refuses to create new files; use Pi's write tool for that
• requires marker-based partial edits for non-trivial existing files
• keeps file I/O inside Pi and uses Morph only for the semantic merge step
• returns udiff, merged output, and change stats in tool details

Validation snapshot

Manual package-level validation was run against the real Morph service on a temporary math.ts file.

Verified outcomes:

• dry run succeeded without changing the file
• real write succeeded and updated the file
• SDK returned change stats and unified diff output
• registered command surface includes morph-status

Observed sample change summary from validation:

• +3 -0 ~0

Development

bun install
bun run typecheck
bun run lint

Autofix:

bun run fix

Formatting only:

bun run format

License

MIT