feat(memory-cli): cross-platform IDE detection for memory init

[bplatz]

fluree memory init used to detect installed IDEs primarily via macOS-specific /Applications/<App>.app probes, with fallbacks limited to ~/.<app> markers. That left Linux and Windows in a "must have launched the IDE once" hole, and made Claude Code's detection (no .app bundle) weaker than the others on every OS.

This PR makes detection multi-signal and cross-platform, hardens the IDE config installers against clobbering, and corrects Claude Code's project-root handling so running fluree memory init from a subdirectory behaves identically to running it from the repo root.

What changed

Detection refactor (fluree-db-cli/src/commands/memory.rs)

• Factored all filesystem/env probing behind a DetectionEnv trait. Production code uses RealEnv (delegates to std::env, dirs, std::fs); tests use FakeEnv.
• Each IDE is now detected via four signal classes — any one is enough:
  1. Binary on PATH (claude, code, cursor, windsurf, zed). claude is now a first-class signal — previously Claude Code only matched ~/.claude/.
  2. macOS app bundle in /Applications or ~/Applications.
  3. Home-dir marker (~/.claude, ~/.cursor, ~/.vscode, ~/.codeium/windsurf, ~/.zed, ~/.config/zed, ~/.claude.json).
  4. User-config dir under dirs::config_dir() — ~/.config/Code on Linux, ~/Library/Application Support/Cursor on macOS, %APPDATA%\Windsurf on Windows, etc. This is what closes the "launched once" gap on Linux/Windows.

Claude Code project-root handling

claude_code_already_configured used the canonicalized cwd as the lookup key — wrong when init is run from a subdirectory, since Claude stores its projects map keyed by the repo root. Now:

• Probes canonical(project_root) → project_root → canonical(cwd) in order.
• install_claude_code spawns claude mcp add with .current_dir(project_root).
• The CLAUDE.md append target is <project_root>/CLAUDE.md, not the cwd-relative Path::new("CLAUDE.md").

Refuse-to-clobber for IDE configs

read_or_default() silently replaced any unreadable/unparsable JSON with a fresh default — fine for missing files, dangerous for JSONC, hand-edits, invalid UTF-8, or permission errors. Replaced with load_config() returning:

• Default — file missing (ErrorKind::NotFound) or empty.
• Parsed — valid JSON.
• Unsafe { reason } — any other state. Installer prints a snippet to paste manually and returns InstallOutcome::Skipped.

This now applies to Cursor, VS Code, Windsurf, and Zed (Zed was already safe; the others now match).

Skipped vs installed accounting

Previously, install_tool() -> Ok(()) covered both "actually installed" and "refused to overwrite, printed snippet." So the user would see "Configured N tools" with N including refused targets. Fixed with a new InstallOutcome { Installed, Skipped } enum; run_init only counts Installed and now prints a separate "Skipped N tools (see manual snippet above)" line when needed. Claude Code's failed claude mcp add (binary missing, non-zero exit) also reports Skipped.

Windows PATHEXT fallback

The PATH probe previously checked nothing if PATHEXT was unset or empty. Now falls back to .COM / .EXE / .BAT / .CMD and also tries the bare name (so an extensionless file still matches).

macOS app-probe tidying

macos_app_installed now early-returns when system_applications_dir is None, so ~/Applications is no longer probed on Linux/Windows (matches the docs).

canonicalize moved behind DetectionEnv

claude_code_already_configured no longer reaches into std::fs::canonicalize directly — exposes the test seam fully.

Tests

21 unit tests in commands::memory::tests:

• project_root_walks_up_to_git_marker, project_root_falls_back_to_cwd_when_no_marker
• Per-IDE presence: claude_present_via_path, claude_present_via_home_marker, claude_absent_when_no_signal, vscode_present_via_config_dir, cursor_present_via_config_dir, windsurf_present_via_config_dir
• macOS probe: macos_app_probe_checks_both_system_and_user_applications, macos_app_probe_is_noop_when_system_dir_unset
• path_extensions_unix_returns_bare_name_only
• Claude already-configured: claude_already_configured_matches_project_root_from_nested_cwd, claude_already_configured_returns_false_when_other_project
• End-to-end detection: detect_returns_empty_on_empty_env, detect_finds_claude_via_path_only, detect_flags_already_configured_via_project_mcp_json
• load_config matrix: missing → Default, empty → Default, JSONC → Unsafe, invalid UTF-8 → Unsafe, valid JSON → Parsed

Docs

• docs/memory/cli/init.md — added Detection signals section + manual-fallback pointer.
• docs/memory/reference/ide-matrix.md — replaced macOS-centric wording with the four signal classes; added "running from a subdir" note.
• docs/cli/memory.md — added Detection signals subsection under fluree memory init.
• docs/memory/cli/mcp-install.md — documented the refuse-to-overwrite policy for non-Zed targets.