nevaforget
a462b2cf06
Fingerprint auth was missing because moongreet rejected multi-stage auth_message sequences from greetd. With pam_fprintd.so in the PAM stack, greetd sends non-secret prompts for fingerprint and secret prompts for password — moongreet now handles both in a loop. - Replace single-pass auth with multi-stage auth_message loop - fprintd D-Bus probe (gio::DBusProxy) for UI feedback only - Fingerprint label shown when device available and fingers enrolled - 60s socket timeout when fingerprint available (pam_fprintd scan time) - Config option: [appearance] fingerprint-enabled (default: true) - Fix: password entry focus loss after auth error (grab_focus while widget was insensitive — now re-enable before grab_focus)
36 lines
3.6 KiB
Markdown
36 lines
3.6 KiB
Markdown
# Decisions
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## 2026-03-29 – Fingerprint authentication via greetd multi-stage PAM
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- **Who**: Ragnar, Dom
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- **Why**: moonlock supports fprintd but moongreet rejected multi-stage auth. Users with enrolled fingerprints couldn't use them at the login screen.
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- **Tradeoffs**: Direct fprintd D-Bus verification (like moonlock) can't start a greetd session — greetd controls session creation via PAM. Using greetd multi-stage means PAM decides the auth order (fingerprint first, then password fallback), not truly parallel. Acceptable — matches standard pam_fprintd behavior.
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- **How**: Replace single-pass auth with a loop over auth_message rounds. Secret prompts get the password, non-secret prompts (fprintd) get None and block until PAM resolves. fprintd D-Bus probe (gio::DBusProxy) only for UI — detecting device availability and enrolled fingers. 60s socket timeout when fingerprint available. Config option `fingerprint-enabled` (default true).
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## 2026-03-28 – Remove embedded wallpaper from binary
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- **Who**: Selene, Dom
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- **Why**: Wallpaper is installed by moonarch to /usr/share/moonarch/wallpaper.jpg. Embedding a 374K JPEG in the binary is redundant. GTK background color (Catppuccin Mocha base) is a clean fallback.
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- **Tradeoffs**: Without moonarch installed AND without config, greeter shows plain dark background instead of wallpaper. Acceptable — that's the expected minimal state.
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- **How**: Remove wallpaper.jpg from GResources, return None from resolve_background_path when no file found, skip wallpaper window creation and background picture when no path available.
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## 2026-03-28 – GPU blur via GskBlurNode replaces CPU blur
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- **Who**: Ragnar, Dom
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- **Why**: CPU-side Gaussian blur (`image` crate) blocked the GTK main thread for 500ms–2s on 4K wallpapers at cold cache. Disk cache and async orchestration added significant complexity.
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- **Tradeoffs**: GPU blur quality is slightly different (box-blur approximation vs true Gaussian), acceptable for wallpaper backgrounds. Removes `image` crate dependency entirely (~15 transitive crates eliminated). No disk cache needed.
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- **How**: `Snapshot::push_blur()` + `GskRenderer::render_texture()` on `connect_realize`. Blur happens once on the GPU when the widget gets its renderer, producing a concrete `gdk::Texture`. Zero startup latency. Symmetric with moonlock and moonset.
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## 2026-03-28 – Optional background blur via `image` crate (superseded)
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- **Who**: Selene, Dom
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- **Why**: Blurred wallpaper as greeter background is a common UX pattern for login screens
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- **Tradeoffs**: Adds `image` crate dependency (~15 transitive crates); CPU-side Gaussian blur at load time adds startup latency proportional to image size and sigma. Acceptable because blur runs once and the texture is shared across monitors.
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- **How**: `load_background_texture(bg_path, blur_radius)` loads texture, optionally applies `imageops::blur()`, returns blurred `gdk::Texture`. Config option `background-blur: Option<f32>` in `[appearance]` TOML section.
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## 2026-03-28 – Audit fixes for shared wallpaper texture (v0.4.1)
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- **Who**: Selene, Dominik
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- **Why**: Quality, performance, and security audits flagged issues in `load_background_texture()`, debug logging, and greetd error handling
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- **Tradeoffs**: GResource path now requires UTF-8 (returns `None` for non-UTF-8 instead of aborting); 50 MB wallpaper limit is generous but prevents OOM; debug logging off by default trades observability for security
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- **How**: GResource branch via `resources_lookup_data()` + `from_bytes()` (no abort), file size limit, error details only at debug level, `MOONGREET_DEBUG` env var for log level, greetd retry path truncation matching `show_greetd_error()`
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