feat: auto-detect project config on first open

[Simonstorms]

Motivation

I always had two problems with Emdash: worktrees didn't really work out of the box because the setup
script wasn't configured, and I couldn't find where to edit the config (should have read the docs).
This feature fixes both by auto-detecting your project setup and showing the settings file on project
creation, so new users immediately see where to edit the config.

Summary

• Auto-detect package manager, install/run scripts, and env files when a project is first opened (no
  .emdash.json yet)
• Show detected config in a review modal so the user can confirm or edit before saving
• Extract shared default preserve patterns to src/shared/lifecycle.ts to avoid duplication

Changes

• New: ProjectDetectionService.ts — detects Node/Python/Ruby/Rust/Go/Java/PHP/Elixir projects,
  scans for env files via git ls-files
• Modified: fsIpc.ts — returns detected config (without writing) when .emdash.json is missing
• Modified: ProjectMainView.tsx — auto-opens config editor on first project open
• Modified: ConfigEditorModal.tsx — adds auto-detect banner, Confirm button, cancel writes
  defaults
• Modified: lifecycle.ts — shared DEFAULT_PRESERVE_PATTERNS and DEFAULT_EMDASH_CONFIG
• Modified: WorktreeService.ts — imports shared constants instead of local duplicates

Demo

Screen.Recording.2026-02-11.at.15.34.33.mov

Test plan

• Open a project that already has .emdash.json — nothing should change
• Click Cancel on auto-detect modal — defaults written, re-opening shows standard config
• Delete .emdash.json from a Node/pnpm project, re-open — should detect pnpm install and
  correct env files

[vercel]

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[greptile-apps]

Greptile Overview

Greptile Summary

This PR adds first-open project config auto-detection when a repo does not yet have an .emdash.json. In the main process, fs:getProjectConfig now returns a synthesized config (scripts + preserve patterns) with an isNew flag rather than writing a default file immediately. The renderer uses that isNew signal to automatically open the config editor and show an “auto-detected” banner with a Confirm action; canceling for a new config writes the standard defaults so subsequent opens don’t re-trigger detection. The shared default preserve patterns and default config object are moved to src/shared/lifecycle.ts and reused by both worktree preservation and the config UI.

Confidence Score: 5/5

• This PR looks safe to merge with low functional risk.
• Changes are localized to config detection/UX, reuse existing ignored-file scanning behavior already used for worktree preservation, and maintain backwards compatibility when an existing .emdash.json is present. No definite correctness issues found in the changed code paths.
• src/main/services/ProjectDetectionService.ts and src/renderer/components/ConfigEditorModal.tsx (behavior on cancel/confirm should match intended UX).

Important Files Changed

Filename	Overview
src/main/services/ProjectDetectionService.ts	Adds project config auto-detection (scripts + env/preservePatterns) used when .emdash.json is missing; logic aligns with existing ignored-file preservation.
src/main/services/WorktreeService.ts	Replaces local default preserve patterns with shared DEFAULT_PRESERVE_PATTERNS; no behavior change beyond constant source.
src/main/services/fsIpc.ts	fs:getProjectConfig now returns detected config without writing when .emdash.json is missing and adds isNew flag; otherwise reads existing file.
src/renderer/components/ConfigEditorModal.tsx	Adds auto-detect banner/Confirm UX and writes defaults on cancel for new configs; behavior matches PR description though cancel discards detected content.
src/renderer/components/ProjectMainView.tsx	On project open, preloads config and auto-opens editor when config is newly detected; ensures state resets on project change/close.
src/renderer/types/electron-api.d.ts	Extends getProjectConfig return type with optional isNew flag to support auto-detect flow.
src/shared/lifecycle.ts	Introduces shared DEFAULT_PRESERVE_PATTERNS and DEFAULT_EMDASH_CONFIG constants for reuse across main/renderer.

Sequence Diagram

sequenceDiagram
  participant PMV as ProjectMainView
  participant CEM as ConfigEditorModal
  participant API as electronAPI (preload)
  participant IPC as fsIpc (main)
  participant DET as ProjectDetectionService
  participant FS as Filesystem

  PMV->>API: getProjectConfig(projectPath)
  API->>IPC: invoke fs:getProjectConfig

  alt config exists
    IPC->>FS: read .emdash.json
    FS-->>IPC: content
    IPC-->>API: success + content + isNew=false
  else config missing
    IPC->>DET: detectConfig(projectPath)
    DET->>FS: check marker files
    DET->>FS: git ls-files (ignored/untracked)
    DET-->>IPC: detected config
    IPC-->>API: success + detected content + isNew=true
  end

  API-->>PMV: result

  opt auto-detected
    PMV->>PMV: open ConfigEditorModal
    PMV->>CEM: render (isAutoDetected=true)
    CEM->>API: getProjectConfig(projectPath)
    API->>IPC: invoke fs:getProjectConfig
    IPC-->>API: content + isNew
    API-->>CEM: content

    alt user confirms/saves
      CEM->>API: saveProjectConfig(projectPath, content)
      API->>IPC: invoke fs:saveProjectConfig
      IPC->>FS: write .emdash.json
      FS-->>IPC: ok
      IPC-->>API: success
      API-->>CEM: success
    else user cancels (new config)
      CEM->>API: saveProjectConfig(projectPath, DEFAULT_CONFIG)
      API->>IPC: invoke fs:saveProjectConfig
      IPC->>FS: write .emdash.json
      IPC-->>API: success
      API-->>CEM: success (ignored)
    end
  end

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