diff --git a/apps/figcraft-web/src/web.rs b/apps/figcraft-web/src/web.rs
index 802d229a..40451d43 100644
--- a/apps/figcraft-web/src/web.rs
+++ b/apps/figcraft-web/src/web.rs
@@ -71,6 +71,9 @@ struct WebShell {
 impl eframe::App for WebShell {
     // eframe runs `logic` for visible tabs and, with only `run_logic`, for hidden ones: keep
     // autosave/live/control deadlines moving without a paint. `FigApp::ui` does not repeat it.
+    /// Run the browser shell's eframe logic callback: guard `background_tick` so hidden tabs
+    /// still advance autosave, live and control deadlines without painting. `FigApp::ui` does
+    /// not repeat it.
     fn logic(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
         figcraft_ui_egui::windows::guard(&mut self.fig, ctx, |fig| fig.background_tick(ctx));
     }
diff --git a/apps/figcraft/src/control_server.rs b/apps/figcraft/src/control_server.rs
index 2af5610d..ada44c0f 100644
--- a/apps/figcraft/src/control_server.rs
+++ b/apps/figcraft/src/control_server.rs
@@ -97,6 +97,9 @@ fn spawn_connection(stream: TcpStream, queue: Queue, ctx: CtxSlot, workers: &mut
     }
 }
 
+/// Serve one control connection: read bounded JSON lines, reject oversized frames and a
+/// full queue, queue one request, wait under its gate, and write one reply. Non-JSON input
+/// answers with an error and closes the connection so HTTP body lines cannot become commands.
 fn serve(mut out: TcpStream, queue: Queue, ctx: CtxSlot, timeout: Duration) -> std::io::Result<()> {
     out.set_read_timeout(Some(timeout))?;
     out.set_write_timeout(Some(timeout))?;
diff --git a/apps/figcraft/src/control_server_tests.rs b/apps/figcraft/src/control_server_tests.rs
index 6144cdf3..f29a7773 100644
--- a/apps/figcraft/src/control_server_tests.rs
+++ b/apps/figcraft/src/control_server_tests.rs
@@ -28,6 +28,7 @@ fn reply(reader: &mut BufReader<TcpStream>) -> Value {
     serde_json::from_str(&line).unwrap()
 }
 
+/// Build a `ui.inspect` control request with a throwaway reply channel.
 fn request() -> ControlRequest {
     ControlRequest { id: json!(0), method: "ui.inspect".into(), params: json!({}), reply: mpsc::channel().0, state: Default::default() }
 }
@@ -115,6 +116,8 @@ fn full_queue_rejects_before_dispatch_and_ui_queue_stays_bounded() {
     worker.join().unwrap().unwrap();
 }
 
+/// Asserts a commit that writes the file and queues its reply wins the gate: the transport's
+/// timeout branch consumes that reply and leaves the state `Replied`.
 #[test]
 fn a_committed_reply_wins_over_the_transport_timeout() {
     let dir = std::env::temp_dir().join(format!("figcraft-control-commit-{}", std::process::id()));
@@ -139,6 +142,7 @@ fn a_committed_reply_wins_over_the_transport_timeout() {
     let _ = std::fs::remove_dir_all(&dir);
 }
 
+/// Asserts a zero-duration wait reports `Timeout` and cancels the open gate.
 #[test]
 fn a_timeout_cancels_an_open_request() {
     let gate = RequestGate::new();
@@ -147,6 +151,8 @@ fn a_timeout_cancels_an_open_request() {
     assert_eq!(gate.state(), RequestState::Cancelled, "nothing may write after the timeout");
 }
 
+/// Asserts a closed reply channel reports `Disconnected` and leaves the gate `Open`, not
+/// cancelled.
 #[test]
 fn a_disconnected_reply_channel_is_not_reported_as_a_timeout() {
     let gate = RequestGate::new();
@@ -268,6 +274,9 @@ fn a_limit_sized_frame_is_accepted_at_eof() {
     worker.join().unwrap().unwrap();
 }
 
+/// Asserts expired requests stop occupying the UI queue cap, a later request is admitted
+/// and answered, and a window that finally draws discards its expired command before
+/// dispatch.
 #[test]
 fn timed_out_requests_release_a_full_deferred_ui_queue() {
     use figcraft_ui_egui::{FigApp, NoServices, control, windows};
diff --git a/apps/figcraft/src/main.rs b/apps/figcraft/src/main.rs
index be380c60..4a1488ad 100644
--- a/apps/figcraft/src/main.rs
+++ b/apps/figcraft/src/main.rs
@@ -62,6 +62,9 @@ struct App {
 }
 
 impl eframe::App for App {
+    /// Native eframe logic callback: store the first context, drain control requests, run
+    /// guarded background work, poll macOS open events, handle close requests and title
+    /// changes, and schedule recovery repaints on the app clock.
     fn logic(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
         {
             let mut slot = self.ctx_slot.lock().unwrap_or_else(std::sync::PoisonError::into_inner);
diff --git a/crates/collab-net/src/sessions_tests.rs b/crates/collab-net/src/sessions_tests.rs
index 3c39e4d8..cf569a6d 100644
--- a/crates/collab-net/src/sessions_tests.rs
+++ b/crates/collab-net/src/sessions_tests.rs
@@ -89,6 +89,9 @@ fn rect(s: &mut Session) -> u64 {
     s.execute("shape.rectangle", &json!({"x": 10, "y": 10, "width": 40, "height": 30})).unwrap()["id"].as_u64().unwrap()
 }
 
+/// Asserts two files are hosted and joined independently: each has its own port, session and
+/// edits, presence stays in its file's session, and closing one file's session leaves the
+/// other live.
 #[test]
 fn two_files_are_hosted_and_joined_independently() {
     let mut host = session("Hana");
diff --git a/crates/engine/src/cmd/edit.rs b/crates/engine/src/cmd/edit.rs
index 044ae884..38b24ea6 100644
--- a/crates/engine/src/cmd/edit.rs
+++ b/crates/engine/src/cmd/edit.rs
@@ -601,6 +601,10 @@ pub fn design_clipboard_buffer(html: &str) -> Option<Vec<u8>> {
     figcraft_format::fig::is_fig(&bytes).then_some(bytes)
 }
 
+/// Paste design layers from clipboard HTML or base64 `data`: decode and reject missing,
+/// invalid or oversized data, load a temporary `.fig`, take its top-level page layers,
+/// store them as a foreign-file clipboard source with a bumped layers generation, then
+/// delegate to `paste` and append import warnings.
 fn paste_design_layers(s: &mut Session, p: &Value) -> Result<Value> {
     const CMD: &str = "edit.pasteDesignLayers";
     let bytes = match (string(p, "html"), string(p, "data")) {
diff --git a/crates/engine/src/text_behaviour_tests.rs b/crates/engine/src/text_behaviour_tests.rs
index d88066cb..8cd8b145 100644
--- a/crates/engine/src/text_behaviour_tests.rs
+++ b/crates/engine/src/text_behaviour_tests.rs
@@ -134,6 +134,8 @@ fn ime_composition_with_cjk() {
     assert!(s.ds().unwrap().text_edit.as_ref().unwrap().preedit.is_none());
 }
 
+/// Asserts `delete_surrounding_bytes` removes an exact UTF-8 byte range across CJK and a
+/// supplementary emoji, leaves nothing past the start, and the whole edit is one undo step.
 #[test]
 fn ime_delete_surrounding_bytes_is_exact_and_one_undo_step() {
     // 0.37's `DeleteSurroundingBytes` counts UTF-8 bytes around the selection, before the paired
@@ -156,6 +158,9 @@ fn ime_delete_surrounding_bytes_is_exact_and_one_undo_step() {
     assert_eq!(chars(&s, t), "ab\u{4F60}\u{597D}c\u{1F600}d", "one undo restores the whole session");
 }
 
+/// Asserts a byte range that only partly covers a character leaves it in place, while an
+/// exact range deletes it, and a selection survives for the paired commit with its
+/// direction preserved.
 #[test]
 fn ime_delete_surrounding_bytes_keeps_partial_characters_and_selection() {
     // The fork deletes the byte range exactly and leaves a character the range only partly
diff --git a/crates/engine/src/textedit.rs b/crates/engine/src/textedit.rs
index 9c62c331..6551783c 100644
--- a/crates/engine/src/textedit.rs
+++ b/crates/engine/src/textedit.rs
@@ -69,6 +69,8 @@ pub struct ImeSurrounding {
 /// A mutex (rather than an atomic) also works on wasm32 targets without 64-bit atomics.
 static EDITING_SESSION: LazyLock<Mutex<u64>> = LazyLock::new(|| Mutex::new(0));
 
+/// Return the next editing-session token from a mutex-protected counter (`wrapping_add`).
+/// Zero is a valid token; the mutex also works on wasm32 without 64-bit atomics.
 fn next_editing_session() -> u64 {
     let mut session = match EDITING_SESSION.lock() {
         Ok(session) => session,
@@ -143,6 +145,9 @@ fn range(te: &TextEdit) -> (usize, usize) {
     (te.caret.min(te.anchor), te.caret.max(te.anchor))
 }
 
+/// Apply an unconditional text-model mutation through `edit_if`, whose success clears the
+/// composition, clamps caret and anchor to the character count, marks a `characters` override
+/// when the node is source-backed, normalizes the document and bumps the revision.
 fn edit(s: &mut Session, f: impl FnOnce(&mut TextData, &mut TextEdit)) -> Result<()> {
     edit_if(s, |t, te| {
         f(t, te);
@@ -230,6 +235,11 @@ pub fn insert_ime_commit(s: &mut Session, text: &str) -> Result<ImeInsertion> {
     insert_model(s, text, true)
 }
 
+/// Insert committed text, optionally as an IME commit: normalize line endings, drop control
+/// characters except `\n`/`\t`, ignore a bare newline/CR IME commit, clear an active
+/// composition for an empty or control-only IME commit, and turn a committed space after a
+/// line-start `-`, `*` or `1.` into a bulleted/numbered list. Reports whether the insertion was
+/// plain, transformed, or a no-op.
 fn insert_model(s: &mut Session, text: &str, ime_commit: bool) -> Result<ImeInsertion> {
     // Stock `TextEdit` deliberately ignores these two commits (they are not a mutation); only a
     // real commit may do so, since typing Enter goes through `insert`.
@@ -894,6 +904,9 @@ mod tests {
         e
     }
 
+    /// Asserts double-clicking a text layer selects all text, a second double-click selects the
+    /// word without changing the editing session, and drag and Shift+click extend the
+    /// selection.
     #[test]
     fn pointer_double_click_drag_and_shift_click() {
         let (mut s, id) = setup("Hello world");
@@ -1132,6 +1145,8 @@ mod tests {
         }
     }
 
+    /// Asserts surrounding text is logical UTF-8 text with byte offsets and keeps a reversed
+    /// selection reversed.
     #[test]
     fn ime_surrounding_uses_logical_utf8_bytes_and_keeps_selection_direction() {
         let (mut s, id) = setup("café😀e\u{301}x");
@@ -1146,6 +1161,8 @@ mod tests {
         assert_eq!(ime.owner.document, s.ds().unwrap().uid);
     }
 
+    /// Asserts an active composition is excluded from surrounding text and an empty text layer
+    /// reports an available, empty payload.
     #[test]
     fn ime_surrounding_excludes_the_composition_and_empty_text_is_available() {
         let (mut s, id) = setup("Hi");
@@ -1162,6 +1179,8 @@ mod tests {
         assert_eq!((ime.text.as_str(), ime.cursor, ime.anchor), ("", 0, 0), "an empty layer is available, not unavailable");
     }
 
+    /// Asserts surrounding text is capped at `MAX_IME_SURROUNDING_BYTES`, an exactly budget-sized
+    /// selection is describable, and one byte more is `SelectionTooWide`.
     #[test]
     fn ime_surrounding_is_bounded_and_a_too_wide_selection_is_explicitly_unavailable() {
         let long = "a".repeat(5000);
@@ -1182,6 +1201,8 @@ mod tests {
         assert_eq!(ime_surrounding(&s), Err(ImeSurroundingUnavailable::SelectionTooWide));
     }
 
+    /// Asserts edits and caret moves keep the same IME owner, while ending and beginning a new
+    /// edit session changes the generation.
     #[test]
     fn ime_owner_is_stable_through_edits_and_the_session_changes_on_begin() {
         let (mut s, id) = setup("Hello");
@@ -1197,6 +1218,8 @@ mod tests {
         assert_ne!(replaced.editing_session, first.editing_session, "a new edit session is a replacement epoch");
     }
 
+    /// Asserts byte deletion around a reversed selection removes whole characters on both
+    /// sides, keeps the selected text and direction, and a final no-op leaves the text alone.
     #[test]
     fn ime_delete_surrounding_bytes_keeps_the_reversed_selection_and_deletes_around_it() {
         let (mut s, id) = setup("ab你好cd");
@@ -1215,6 +1238,8 @@ mod tests {
         assert_eq!(data(&s, id).characters, "你好", "a no-op delete does not touch the text");
     }
 
+    /// Asserts character deletion keeps and shifts the selection, and a no-op delete leaves an
+    /// active composition and the revision untouched.
     #[test]
     fn ime_delete_surrounding_chars_keeps_the_selection_and_ignores_a_no_op() {
         let (mut s, id) = setup("ab你好cd");
@@ -1235,6 +1260,7 @@ mod tests {
         assert_eq!(s.ds().unwrap().revision, revision);
     }
 
+    /// Asserts a text layer in another document has a different IME owner.
     #[test]
     fn ime_owner_identity_changes_with_the_document() {
         let (mut s, id) = setup("Hi");
@@ -1250,6 +1276,8 @@ mod tests {
         assert_eq!(second.node, other);
     }
 
+    /// Asserts a space committed after a line-start `-` becomes a bulleted list and reports
+    /// `Transformed`; a plain `"x"` commit reports `Plain`, and an empty commit reports `Nothing`.
     #[test]
     fn ime_commit_reports_list_autoformat_as_an_application_transformation() {
         let (mut s, id) = setup("-");
@@ -1261,6 +1289,8 @@ mod tests {
         assert_eq!(insert_ime_commit(&mut s, "").unwrap(), ImeInsertion::Nothing);
     }
 
+    /// Asserts CRLF normalization reports `Transformed`, control-only input reports `Nothing`,
+    /// and bare newline/CR commits are ignored while a live composition remains.
     #[test]
     fn ime_commit_normalisation_is_a_transformation_and_a_bare_newline_is_ignored() {
         let (mut s, id) = setup("Hi");
@@ -1283,6 +1313,8 @@ mod tests {
         assert_eq!(data(&s, id).characters, "Hia\nb\n");
     }
 
+    /// Asserts an empty or control-only IME commit ends a live composition (bumping the revision
+    /// once), inserts nothing, and is a harmless no-op when no composition is active.
     #[test]
     fn an_empty_ime_commit_ends_the_composition_without_inserting_text() {
         let (mut s, id) = setup("Hello");
diff --git a/crates/engine/src/textfit_tests.rs b/crates/engine/src/textfit_tests.rs
index f9508942..e35f810c 100644
--- a/crates/engine/src/textfit_tests.rs
+++ b/crates/engine/src/textfit_tests.rs
@@ -64,6 +64,8 @@ fn a_one_word_last_line_is_avoided() {
     assert!(l.lines.len() == 1 || words.split_whitespace().count() > 1 || words.contains('\u{a0}'), "{words:?}");
 }
 
+/// Asserts `data.fill` keeps a short copy's font size, shrinks a long copy, and leaves the
+/// source text layer untouched.
 #[test]
 fn data_fill_sizes_each_copys_text() {
     figcraft_text::scan_system_fonts();
diff --git a/crates/engine/src/tools.rs b/crates/engine/src/tools.rs
index e6776d2c..e65afe2c 100644
--- a/crates/engine/src/tools.rs
+++ b/crates/engine/src/tools.rs
@@ -2010,6 +2010,10 @@ impl Session {
         Ok(())
     }
 
+    /// Handle a double-click gesture: finish a pen path, rename or click labels/widgets,
+    /// cancel an in-progress move/resize/draw/marquee, handle board double-clicks, enter text
+    /// editing (select-all on entry, word-select inside the running edit), enter vector editing
+    /// for selected shapes, and step groups/frames one level deeper.
     fn double_click(&mut self, ev: &PointerEvent) -> Result<()> {
         let ds = self.ds()?;
         let (doc, sel, page) = (ds.doc.clone(), ds.selection.clone(), ds.page);
diff --git a/crates/text/build.rs b/crates/text/build.rs
index ecca6a45..ba087983 100644
--- a/crates/text/build.rs
+++ b/crates/text/build.rs
@@ -6,6 +6,9 @@
 use std::fmt::Write as _;
 use std::path::PathBuf;
 
+/// Font build script: emit `craft_fonts.rs` from `input_fonts`, passing the
+/// `CRAFT_FONTS_DIR`, `CRAFT_FONTS_REQUIRED`, wasm target and `FIGCRAFT_EMBED_CJK` inputs;
+/// report generation and write failures with `cargo::error`.
 fn main() {
     println!("cargo::rerun-if-env-changed=CRAFT_FONTS_DIR");
     println!("cargo::rerun-if-env-changed=CRAFT_FONTS_REQUIRED");
@@ -77,6 +80,10 @@ struct Catalog {
     faces: Vec<(String, String)>,
 }
 
+/// Parse a font manifest of `family | style | file | scripts` rows into `CraftFont`
+/// entries: skip Adobe-authored families, skip CJK unless requested, keep the web catalog
+/// to its budgeted families, canonicalize and watch each face, and emit `include_bytes!`
+/// items.
 fn craft_fonts(dir: &std::path::Path, manifest_rel: &str, wasm: bool, embed_cjk: bool) -> Result<Catalog, String> {
     let manifest = dir.join(manifest_rel);
     watch(&manifest);
@@ -121,6 +128,8 @@ mod tests {
     struct Fixture(PathBuf);
 
     impl Fixture {
+        /// Test fixture: create a unique temporary directory, write a synthetic face file and
+        /// install the default Georgian manifest.
         fn new() -> Self {
             let dir = std::env::temp_dir().join(format!("fig-font-input-{}-{}", std::process::id(), NEXT.fetch_add(1, Ordering::Relaxed)));
             std::fs::create_dir_all(dir.join("fonts")).unwrap();
@@ -131,6 +140,7 @@ mod tests {
             fixture
         }
 
+        /// Test fixture: write manifest rows that all point at the fixture's `fonts/face.ttf` face.
         fn manifest(&self, name: &str, faces: &[(&str, &str)]) {
             let text = faces.iter().map(|(family, style)| format!("{family} | {style} | fonts/face.ttf | Latn\n")).collect::<String>();
             std::fs::write(self.0.join("fonts").join(name), text).unwrap();
@@ -138,11 +148,15 @@ mod tests {
     }
 
     impl Drop for Fixture {
+        /// Remove the fixture's temporary directory, ignoring errors.
         fn drop(&mut self) {
             let _ = std::fs::remove_dir_all(&self.0);
         }
     }
 
+    /// Asserts the native Latin catalog keeps its 43 permitted presentation faces, the web
+    /// catalog keeps only the four Inter faces, Adobe-authored families are absent, and
+    /// permitted native faces remain.
     #[test]
     fn restored_latin_catalog_preserves_permitted_native_faces_and_web_budget() {
         let f = Fixture::new();
@@ -160,6 +174,7 @@ mod tests {
         assert!(input_fonts(Some(&f.0), true, true, false).is_ok());
     }
 
+    /// Asserts required web input rejects a catalog missing Inter Regular or Inter SemiBold.
     #[test]
     fn required_web_rejects_core_only_and_partial_latin_catalogs() {
         let f = Fixture::new();
@@ -168,6 +183,8 @@ mod tests {
         assert!(input_fonts(Some(&f.0), true, true, false).unwrap_err().contains("Inter SemiBold"));
     }
 
+    /// Asserts required web input embeds the Inter and Georgian catalogs (three entries) and
+    /// rejects a manifest without Noto Sans Georgian Regular.
     #[test]
     fn required_web_embeds_both_catalogs_and_requires_georgian() {
         let f = Fixture::new();
@@ -180,6 +197,8 @@ mod tests {
         assert!(input_fonts(Some(&f.0), true, true, false).unwrap_err().contains("Noto Sans Georgian Regular"));
     }
 
+    /// Asserts absent font input is empty when optional and an error when required, while present
+    /// input includes Noto Sans Georgian.
     #[test]
     fn optional_and_native_inputs_keep_their_existing_policy() {
         let f = Fixture::new();
@@ -189,6 +208,8 @@ mod tests {
         assert!(input_fonts(Some(&f.0), false, true, false).unwrap().contains("Noto Sans Georgian"));
     }
 
+    /// Asserts required web input rejects a manifest whose face file is missing, even when every
+    /// face row is listed.
     #[test]
     fn required_web_rejects_missing_asset_even_with_all_face_rows() {
         let f = Fixture::new();
diff --git a/crates/ui-egui/src/a11y.rs b/crates/ui-egui/src/a11y.rs
index 79a28118..3c5fafb6 100644
--- a/crates/ui-egui/src/a11y.rs
+++ b/crates/ui-egui/src/a11y.rs
@@ -253,6 +253,8 @@ struct Shared {
     name: String,
 }
 
+/// Run `f` on the per-context temporary `Shared` accessibility state keyed by
+/// `figcraft_a11y`.
 fn shared<R>(ctx: &Context, f: impl FnOnce(&mut Shared) -> R) -> R {
     ctx.data_mut(|d| f(d.get_temp_mut_or_default::<Shared>(Id::unique("figcraft_a11y"))))
 }
diff --git a/crates/ui-egui/src/a11y_tests.rs b/crates/ui-egui/src/a11y_tests.rs
index a2c54cbe..14be637d 100644
--- a/crates/ui-egui/src/a11y_tests.rs
+++ b/crates/ui-egui/src/a11y_tests.rs
@@ -404,6 +404,8 @@ fn the_align_buttons_are_off_for_a_layer_alone_on_the_page() {
     assert!(!align_left(&tree(&mut u)), "one in a frame aligns to it");
 }
 
+/// Asserts side-panel and Pages edges are not focusable, and Tab never stops on the
+/// side-panel edges.
 #[test]
 fn the_custom_panel_edges_never_enter_the_keyboard_or_focus_order() {
     // FigCraft's panels are fixed, so egui makes no `panel.__resize` widgets; the draggable edges
diff --git a/crates/ui-egui/src/assets_panel.rs b/crates/ui-egui/src/assets_panel.rs
index e9f0ffce..db0cc0f7 100644
--- a/crates/ui-egui/src/assets_panel.rs
+++ b/crates/ui-egui/src/assets_panel.rs
@@ -164,6 +164,7 @@ enum Act {
     Hide(NodeId, bool),
 }
 
+/// Stable egui id for the assets drag payload.
 fn drag_id() -> Id {
     Id::unique("asset_drag")
 }
@@ -581,6 +582,10 @@ fn render_thumbs(ui: &Ui, w: f32, thumbs: &mut Thumbs, wanted: &[(Source, NodeId
     }
 }
 
+/// Draw the Assets panel: refresh libraries, switch to the libraries view when asked,
+/// otherwise cache a listing keyed by revision, query and library state, render local and
+/// enabled-library assets with reused thumbnails, and dispatch place, style, hide, toggle
+/// and drag actions.
 pub fn show(app: &mut FigApp, ui: &mut Ui) {
     refresh_libraries(app, ui);
     if app.ui.libraries {
@@ -773,6 +778,8 @@ fn drag_feedback(app: &mut FigApp, ui: &mut Ui, doc: &Document, libs: &HashMap<S
     ui.ctx().request_repaint();
 }
 
+/// Draw the 64×64 component ghost on the tooltip layer, using the thumbnail when available
+/// and the component or component-set icon otherwise.
 fn ghost(ui: &Ui, p: Pos2, set: bool, tex: Option<egui::TextureHandle>) {
     let t = Tokens::get(ui.ctx());
     let painter = ui.ctx().layer_painter(egui::LayerId::new(egui::Order::Tooltip, Id::unique("asset_ghost")));
@@ -831,6 +838,10 @@ fn libraries_view(app: &mut FigApp, ui: &mut Ui) {
     });
 }
 
+/// Draw the publish form: status, publishable components/styles/collections, description and
+/// publish buttons. Run `library.publish` locally or publish to the server in the
+/// background, reset the form on success, and report when the file is unsaved so other files
+/// cannot yet use it.
 fn publish_form(app: &mut FigApp, ui: &mut Ui, w: f32, doc: &Document) {
     let form_id = Id::unique("asset_publish_form");
     let mut form: PublishForm = ui.data(|d| d.get_temp(form_id)).unwrap_or_default();
@@ -1010,6 +1021,8 @@ fn usage(app: &mut FigApp, ui: &mut Ui, w: f32, link: &str) {
     ui.add_space(8.0);
 }
 
+/// Draw the libraries enabled in this file with version/count/status, remove and swap
+/// actions, add-file and pasted-link controls, and background fetch/cancel handling.
 fn enabled_libraries(app: &mut FigApp, ui: &mut Ui, w: f32, doc: &Document) {
     let t = Tokens::get(ui.ctx());
     title(ui, w, tr("Libraries in this file"));
diff --git a/crates/ui-egui/src/canvas.rs b/crates/ui-egui/src/canvas.rs
index 4211b3cc..a6770823 100644
--- a/crates/ui-egui/src/canvas.rs
+++ b/crates/ui-egui/src/canvas.rs
@@ -163,6 +163,10 @@ fn pointer_event(app: &FigApp, kind: PointerKind, pos: Pos2, m: &egui::Modifiers
     }
 }
 
+/// Run one canvas pass: update the viewport size and first-fit zoom; handle pointer/key input
+/// and accessibility; draw the drop overlay, guides, live pointer and preedit; request/poll
+/// renders and upload the texture; draw the page background and last texture; then draw overlays,
+/// labels, handles, comments, versions/branch/dev/live UI and the cursor.
 pub fn show(app: &mut FigApp, ui: &mut Ui, worker: &mut Worker) {
     let rect = ui.max_rect();
     app.canvas.rect = rect;
diff --git a/crates/ui-egui/src/clipboard_fence_tests.rs b/crates/ui-egui/src/clipboard_fence_tests.rs
index 9211a4d4..76ddf81c 100644
--- a/crates/ui-egui/src/clipboard_fence_tests.rs
+++ b/crates/ui-egui/src/clipboard_fence_tests.rs
@@ -25,14 +25,17 @@ struct Recorded {
 struct Clipboard(Arc<Mutex<Recorded>>);
 
 impl Services for Clipboard {
+    /// Record a system-clipboard text write in the test clipboard service.
     fn clipboard_set_text(&mut self, s: &str) {
         let mut r = self.0.lock().unwrap();
         r.text.push(s.to_string());
         r.last_text = Some(s.to_string());
     }
+    /// Return the test system clipboard's last text.
     fn clipboard_get_text(&mut self) -> Option<String> {
         self.0.lock().unwrap().last_text.clone()
     }
+    /// Count a PNG clipboard write in the test clipboard service.
     fn clipboard_set_png(&mut self, _w: u32, _h: u32, _rgba: &[u8]) {
         self.0.lock().unwrap().pngs += 1;
     }
@@ -46,6 +49,7 @@ struct Win {
 }
 
 impl Win {
+    /// Create a test window over a session containing one selected rectangle.
     fn new() -> Self {
         let mut s = Session::new();
         s.execute("shape.rectangle", &json!({"x": 10, "y": 10, "width": 100, "height": 50})).unwrap();
@@ -54,6 +58,7 @@ impl Win {
         win
     }
 
+    /// Build a test window around `s` with a recording clipboard service and run three frames.
     fn with_session(s: Session) -> Self {
         let recorded = Arc::new(Mutex::new(Recorded::default()));
         let app = FigApp::new(s, Box::new(Clipboard(recorded.clone())));
@@ -64,6 +69,7 @@ impl Win {
         win
     }
 
+    /// Run one production UI frame with `events` at the next 60 Hz test time.
     fn frame(&mut self, events: Vec<Event>) {
         self.time += 1.0 / 60.0;
         self.app.clock.set_test_now(Some(self.time));
@@ -74,12 +80,15 @@ impl Win {
         out.textures_delta.clear();
     }
 
+    /// Return the recorded `(text writes, PNG writes)` count.
     fn writes(&self) -> (usize, usize) {
         let r = self.recorded.lock().unwrap();
         (r.text.len(), r.pngs)
     }
 }
 
+/// Asserts that a control-channel copy shortcut writes no system clipboard, still runs the
+/// command and is acknowledged.
 #[test]
 fn a_synthetic_copy_shortcut_leaves_the_system_clipboard_alone() {
     let mut w = Win::new();
@@ -106,6 +115,8 @@ fn a_synthetic_copy_shortcut_leaves_the_system_clipboard_alone() {
     assert!(rx.try_recv().is_ok(), "the batch is acknowledged");
 }
 
+/// Asserts copy commands run under the synthetic-control fence write nothing, while the same
+/// command afterwards writes once.
 #[test]
 fn a_copy_command_invoked_for_a_synthetic_click_still_keeps_the_clipboard() {
     let mut w = Win::new();
@@ -120,6 +131,7 @@ fn a_copy_command_invoked_for_a_synthetic_click_still_keeps_the_clipboard() {
     assert_eq!(w.writes(), (1, 0));
 }
 
+/// Return the characters of a text node in the test window.
 fn edit_text(w: &Win, id: NodeId) -> String {
     match &w.app.session.doc().unwrap().node(id).unwrap().kind {
         NodeKind::Text(t) => t.characters.clone(),
@@ -127,6 +139,8 @@ fn edit_text(w: &Win, id: NodeId) -> String {
     }
 }
 
+/// Asserts a synthetic Cut deletes the selected text, keeps the edit session active, writes
+/// no system clipboard, and ends its fence with the frame.
 #[test]
 fn a_synthetic_cut_deletes_the_selection_but_leaves_the_users_clipboard_alone() {
     let mut s = Session::new();
@@ -147,6 +161,8 @@ fn a_synthetic_cut_deletes_the_selection_but_leaves_the_users_clipboard_alone()
     assert!(!w.app.control_synthetic, "the fence ends with the frame");
 }
 
+/// Asserts a programmatic copy leaves the system clipboard alone and invalidates the stale
+/// mirror, so a later user paste uses the system text rather than the programmatic layers.
 #[test]
 fn a_programmatic_copy_does_not_let_a_stale_mirror_hide_the_users_paste() {
     let mut s = Session::new();
diff --git a/crates/ui-egui/src/colorpicker.rs b/crates/ui-egui/src/colorpicker.rs
index 90d00c3f..f1cde02f 100644
--- a/crates/ui-egui/src/colorpicker.rs
+++ b/crates/ui-egui/src/colorpicker.rs
@@ -339,6 +339,8 @@ fn hue_color(ctx: &egui::Context, h: f32) -> Color32 {
     doc_c32(ctx, Hsb { h, s: 1.0, b: 1.0 }.to_color())
 }
 
+/// Draw the saturation/value square and its knob, updating `hsb.s` and `hsb.b` on click or
+/// drag; returns `(changed, done)`.
 fn sv_square(ui: &mut Ui, rect: Rect, hsb: &mut Hsb) -> (bool, bool) {
     // White → hue horizontally, then transparent → black vertically.
     let mut m = Mesh::default();
@@ -377,6 +379,8 @@ fn sv_square(ui: &mut Ui, rect: Rect, hsb: &mut Hsb) -> (bool, bool) {
     (changed, resp.drag_stopped() || resp.clicked())
 }
 
+/// Draw the hue gradient and knob, updating `hsb.h` clamped below 360; returns
+/// `(changed, done)`.
 fn hue_slider(ui: &mut Ui, rect: Rect, hsb: &mut Hsb) -> (bool, bool) {
     let n = 12;
     let mut m = Mesh::default();
@@ -417,6 +421,8 @@ fn slider_knob(ui: &mut Ui, rect: Rect, t: f32, id: Id) -> Option<(f32, bool)> {
     None
 }
 
+/// Draw the checkerboard and transparent-to-opaque alpha gradient with a knob; returns the
+/// new alpha and done state, or `None` when the slider is not interacting.
 fn alpha_slider(ui: &mut Ui, rect: Rect, color: Color) -> Option<(f32, bool)> {
     widgets::checker(&ui.painter().with_clip_rect(rect), rect, rect.height() / 2.0);
     let mut m = Mesh::default();
@@ -441,6 +447,9 @@ pub fn window_id() -> Id {
     Id::unique("color_picker")
 }
 
+/// Draw the colour picker for the current target: close it when there is no target or the
+/// target's selection no longer matches, otherwise apply eyedropper, paint-kind, colour and
+/// gradient-stop edits live, positioned beside a plugin field when applicable.
 pub fn show(app: &mut FigApp, ctx: &egui::Context) {
     let Some(target) = app.ui.picker.clone() else {
         // A colour sampled for a picker that has closed has no paint to go to.
diff --git a/crates/ui-egui/src/control.rs b/crates/ui-egui/src/control.rs
index 4c3be3de..97e62d1f 100644
--- a/crates/ui-egui/src/control.rs
+++ b/crates/ui-egui/src/control.rs
@@ -70,18 +70,22 @@ pub struct RequestGate {
 }
 
 impl RequestGate {
+    /// Create a request gate in its default `Open` state.
     pub fn new() -> Self {
         Self::default()
     }
 
+    /// Return a copy of the gate's current request state.
     pub fn state(&self) -> RequestState {
         *self.state.lock().unwrap_or_else(std::sync::PoisonError::into_inner)
     }
 
+    /// Whether the gate is `Cancelled`.
     pub fn is_cancelled(&self) -> bool {
         self.state() == RequestState::Cancelled
     }
 
+    /// Whether the gate is `Replied`.
     pub fn is_replied(&self) -> bool {
         self.state() == RequestState::Replied
     }
@@ -121,6 +125,7 @@ pub struct ControlRequest {
 }
 
 impl ControlRequest {
+    /// Whether this request's gate is `Cancelled`.
     pub fn is_cancelled(&self) -> bool {
         self.state.is_cancelled()
     }
@@ -147,6 +152,7 @@ struct SlotInner {
 }
 
 impl CaptureSlot {
+    /// Create an empty capture slot for `viewport`, holding a clone of the UI context.
     fn new(ctx: &Context, viewport: egui::ViewportId) -> Arc<Self> {
         Arc::new(Self { inner: Mutex::new(SlotInner::default()), ctx: ctx.clone(), viewport })
     }
@@ -161,6 +167,8 @@ impl CaptureSlot {
         })
     }
 
+    /// Store the first delivered image only while the slot is open and untaken, ignoring later
+    /// or closed deliveries, then wake the viewport after releasing the lock.
     pub(crate) fn complete(&self, image: Arc<egui::ColorImage>) {
         {
             let mut inner = self.inner.lock().unwrap_or_else(std::sync::PoisonError::into_inner);
@@ -214,6 +222,7 @@ pub struct CaptureSpec {
 const SHOT_PNG_OVERHEAD: usize = 64 * 1024;
 
 impl CaptureSpec {
+    /// Return the checked pixel byte count (`width × height × 4`), or `None` on overflow.
     fn bytes(&self) -> Option<usize> {
         self.size_px[0].checked_mul(self.size_px[1])?.checked_mul(4)
     }
@@ -272,6 +281,7 @@ pub struct ShotRequest {
 }
 
 impl ShotRequest {
+    /// Close and drop the capture slot, if any, and zero the reserved byte count.
     fn release(&mut self) {
         if let Some(slot) = self.slot.take() {
             slot.close();
@@ -327,6 +337,7 @@ fn current_spec(ctx: &Context, viewport: egui::ViewportId) -> Option<CaptureSpec
     Some(CaptureSpec { viewport, size_px: [w as usize, h as usize], pixels_per_point: ppp, zoom })
 }
 
+/// Send one reply carrying the request id, ignoring a disconnected receiver.
 fn reply(r: &mut ShotRequest, result: Result<Value, String>) {
     let _ = r.reply.send(ControlReply { id: r.id.clone(), result });
 }
@@ -819,6 +830,8 @@ enum EncodedShot {
 }
 
 impl EncodedShot {
+    /// Deliver the encoded shot: for `File`, write the PNG through `file_access` and return its
+    /// path and dimensions; for `Data`, return the prebuilt result.
     fn finish(self) -> Result<Value, String> {
         match self {
             Self::File { path, png, width, height } => {
diff --git a/crates/ui-egui/src/control_capture_tests.rs b/crates/ui-egui/src/control_capture_tests.rs
index ce4df1aa..6068ce52 100644
--- a/crates/ui-egui/src/control_capture_tests.rs
+++ b/crates/ui-egui/src/control_capture_tests.rs
@@ -12,6 +12,7 @@ use serde_json::json;
 use crate::control::{CaptureSpec, ControlReply, ControlRequest};
 use crate::layers_drag_tests::Ui;
 
+/// Queue a `ui.screenshot` request in the test app and return its reply receiver.
 fn push(u: &mut Ui, id: u64, params: serde_json::Value) -> std::sync::mpsc::Receiver<ControlReply> {
     let (tx, rx) = std::sync::mpsc::channel();
     u.app.control_queue.push(ControlRequest { id: json!(id), method: "ui.screenshot".into(), params, reply: tx, state: Default::default() });
@@ -38,10 +39,13 @@ fn resized_frame(u: &mut Ui, size: egui::Vec2) -> egui::FullOutput {
     out
 }
 
+/// Whether any viewport in the frame output issues a `Screenshot` command.
 fn has_screenshot(out: &egui::FullOutput) -> bool {
     out.viewport_output.values().any(|v| v.commands.iter().any(|c| matches!(c, egui::ViewportCommand::Screenshot(_))))
 }
 
+/// Asserts reverse capture completion replies only to the matching request, then drains both
+/// requests.
 #[test]
 fn two_captures_correlate_by_request_across_reverse_completion() {
     let mut u = Ui::new(Session::empty());
@@ -67,6 +71,7 @@ fn two_captures_correlate_by_request_across_reverse_completion() {
     assert!(u.app.capture.shots.is_empty(), "no retained requests");
 }
 
+/// Asserts a cancelled capture gets no reply and its slot is released.
 #[test]
 fn a_cancelled_capture_never_replies_or_writes() {
     let mut u = Ui::new(Session::empty());
@@ -89,6 +94,7 @@ fn commit_dir(tag: &str) -> std::path::PathBuf {
     dir
 }
 
+/// Asserts cancellation after encoding still prevents the final file write and reply.
 #[test]
 fn a_cancellation_after_encoding_prevents_the_final_write() {
     let dir = commit_dir("cancelled");
@@ -107,6 +113,7 @@ fn a_cancellation_after_encoding_prevents_the_final_write() {
     let _ = std::fs::remove_dir_all(&dir);
 }
 
+/// Asserts a capture that arrives past its deadline reports a timeout and writes no PNG.
 #[test]
 fn a_real_arrival_that_crosses_the_deadline_does_not_write_its_png() {
     let mut u = Ui::new(Session::empty());
@@ -129,6 +136,8 @@ fn a_real_arrival_that_crosses_the_deadline_does_not_write_its_png() {
     let _ = std::fs::remove_dir_all(&dir);
 }
 
+/// Asserts an expiry during encoding reports the timeout under the gate, marks the request
+/// replied and writes no file.
 #[test]
 fn an_expiry_during_encoding_prevents_the_final_write_and_reports_timeout() {
     let dir = commit_dir("expired");
@@ -149,6 +158,8 @@ fn an_expiry_during_encoding_prevents_the_final_write_and_reports_timeout() {
     let _ = std::fs::remove_dir_all(&dir);
 }
 
+/// Asserts a commit before the deadline writes the file and queues one reply, and a second
+/// commit is refused.
 #[test]
 fn a_commit_before_the_deadline_writes_and_queues_its_reply_once() {
     let dir = commit_dir("committed");
@@ -172,6 +183,8 @@ fn a_commit_before_the_deadline_writes_and_queues_its_reply_once() {
     let _ = std::fs::remove_dir_all(&dir);
 }
 
+/// Asserts a capture past its deadline sends one timeout reply, releases its slot, and late
+/// pixels are ignored.
 #[test]
 fn a_capture_after_its_deadline_replies_once_and_late_pixels_are_inert() {
     let mut u = Ui::new(Session::empty());
@@ -191,6 +204,8 @@ fn a_capture_after_its_deadline_replies_once_and_late_pixels_are_inert() {
     assert!(rx.try_recv().is_err(), "a late capture is inert");
 }
 
+/// Asserts the snapshot count budget rejects an over-budget request before issuing, and every
+/// admitted capture still completes under its own id.
 #[test]
 fn a_snapshot_batch_is_capped_before_issuing_over_the_count_budget() {
     let mut u = Ui::new(Session::empty());
@@ -213,6 +228,7 @@ fn a_snapshot_batch_is_capped_before_issuing_over_the_count_budget() {
     rxs.clear();
 }
 
+/// Asserts an undersized readback is not accepted but reissued with one retry and no reply.
 #[test]
 fn an_undersized_readback_is_reissued_instead_of_accepted() {
     let mut u = Ui::new(Session::empty());
@@ -230,6 +246,7 @@ fn an_undersized_readback_is_reissued_instead_of_accepted() {
     assert!(!r.issued, "waits for the settled geometry again");
 }
 
+/// Asserts a one-pixel rounding difference is accepted as the same surface.
 #[test]
 fn a_one_pixel_rounding_difference_is_still_the_same_surface() {
     let mut u = Ui::new(Session::empty());
@@ -245,6 +262,7 @@ fn a_one_pixel_rounding_difference_is_still_the_same_surface() {
     assert!(u.app.capture.shots.is_empty(), "released");
 }
 
+/// Asserts an A→B→A tab switch invalidates the admitted capture with "document changed".
 #[test]
 fn a_document_a_to_b_to_a_switch_is_not_the_admitted_capture() {
     let mut s = Session::empty();
@@ -268,6 +286,8 @@ fn a_document_a_to_b_to_a_switch_is_not_the_admitted_capture() {
     assert!(u.app.capture.shots.is_empty(), "released");
 }
 
+/// Asserts a geometry change bumps the capture epoch and reissues instead of accepting old
+/// pixels.
 #[test]
 fn a_geometry_change_reissues_instead_of_accepting_old_pixels() {
     let mut u = Ui::new(Session::empty());
@@ -288,6 +308,8 @@ fn a_geometry_change_reissues_instead_of_accepting_old_pixels() {
     assert!(!r.issued, "waits for the settled geometry again");
 }
 
+/// Asserts a translucent pixel round-trips through the PNG as straight RGBA without
+/// darkening.
 #[test]
 fn a_translucent_pixel_round_trips_straight_rgba() {
     let img = egui::ColorImage::from_rgba_unmultiplied([1, 1], &[128, 64, 32, 128]);
@@ -298,6 +320,8 @@ fn a_translucent_pixel_round_trips_straight_rgba() {
     assert_eq!(decoded.get_pixel(0, 0).0, [128, 64, 32, 128], "straight alpha is not darkened");
 }
 
+/// Asserts a capture is not issued before three completed real UI frames; the following
+/// completed frame issues it.
 #[test]
 fn a_capture_is_not_issued_before_three_completed_real_ui_frames() {
     let mut u = Ui::new(Session::empty());
@@ -313,6 +337,8 @@ fn a_capture_is_not_issued_before_three_completed_real_ui_frames() {
     assert!(u.app.capture.shots[0].issued, "issued once three frames have presented their layout");
 }
 
+/// Asserts a discarded sizing pass does not count toward capture settling, and the next
+/// completed frame issues it.
 #[test]
 fn a_discarded_sizing_pass_does_not_count_as_a_settled_capture_frame() {
     let mut u = Ui::new(Session::empty());
@@ -327,6 +353,8 @@ fn a_discarded_sizing_pass_does_not_count_as_a_settled_capture_frame() {
     assert!(u.app.capture.shots[0].issued, "the next completed frame issues the capture");
 }
 
+/// Asserts pixels delivered while hidden force a draining paint and are answered rather than
+/// timed out.
 #[test]
 fn a_hidden_window_that_delivers_pixels_is_asked_to_paint_the_draining_pass() {
     let mut u = Ui::new(Session::empty());
@@ -354,6 +382,8 @@ fn a_hidden_window_that_delivers_pixels_is_asked_to_paint_the_draining_pass() {
     assert!(u.app.capture.shots.is_empty(), "released");
 }
 
+/// Asserts a capture for a window with unknown visibility is parked with its deadline and a
+/// paint request, then times out once.
 #[test]
 fn a_capture_for_a_window_with_unknown_visibility_is_admitted_with_a_deadline() {
     let mut u = Ui::new(Session::empty());
@@ -386,6 +416,8 @@ fn a_capture_for_a_window_with_unknown_visibility_is_admitted_with_a_deadline()
     assert!(u.app.capture.shots.is_empty(), "released");
 }
 
+/// Asserts a completed capture is rejected when current geometry is unavailable, failing
+/// closed.
 #[test]
 fn a_completed_capture_is_rejected_when_current_geometry_is_unavailable() {
     let mut u = Ui::new(Session::empty());
@@ -412,6 +444,7 @@ fn a_completed_capture_is_rejected_when_current_geometry_is_unavailable() {
     assert!(u.app.capture.shots.is_empty(), "released");
 }
 
+/// Asserts a tab switch while a capture settles invalidates it with "document changed".
 #[test]
 fn a_capture_belongs_to_the_document_admitted_not_the_one_showing_when_it_arrives() {
     let mut s = Session::empty();
@@ -435,6 +468,8 @@ fn a_capture_belongs_to_the_document_admitted_not_the_one_showing_when_it_arrive
     assert!(u.app.capture.shots.is_empty(), "released");
 }
 
+/// Asserts the capture budget covers the encoding and reply peaks, not just pixels, and an
+/// over-budget resize is rejected before readback.
 #[test]
 fn the_capture_budget_counts_the_encoding_peak_not_only_the_pixels() {
     let fits = CaptureSpec { viewport: egui::ViewportId::ROOT, size_px: [4096, 4096], pixels_per_point: 1.0, zoom: 1.0 };
@@ -462,6 +497,8 @@ fn the_capture_budget_counts_the_encoding_peak_not_only_the_pixels() {
     assert!(!has_screenshot(&out), "over-budget growth is rejected before any readback command");
 }
 
+/// Asserts resizing settling captures rechecks aggregate reserved bytes, rejects the request
+/// that no longer fits, and makes the survivor reserve its real cost.
 #[test]
 fn resizing_settling_captures_rechecks_the_aggregate_reserved_bytes() {
     let mut u = Ui::new(Session::empty());
@@ -481,6 +518,8 @@ fn resizing_settling_captures_rechecks_the_aggregate_reserved_bytes() {
     assert!(!has_screenshot(&out), "neither request was read back using the old small reservation");
 }
 
+/// Asserts an allowed resize restarts settling, issues only after three new-size frames, and
+/// reserves the current cost.
 #[test]
 fn an_allowed_resize_restarts_settling_and_issues_with_the_current_reservation() {
     let mut u = Ui::new(Session::empty());
@@ -518,6 +557,8 @@ fn push_input(u: &mut Ui, id: u64) -> std::sync::mpsc::Receiver<ControlReply> {
     rx
 }
 
+/// Asserts injected input is queued, applied by the presenting pass, and acknowledged once
+/// after that pass.
 #[test]
 fn injected_input_is_acknowledged_only_after_the_pass_that_applies_it() {
     let mut u = Ui::new(Session::empty());
@@ -534,6 +575,8 @@ fn injected_input_is_acknowledged_only_after_the_pass_that_applies_it() {
     assert!(!u.app.control_synthetic, "the fence ends with the frame");
 }
 
+/// Asserts a discarded pass neither acknowledges nor replays an injected batch; the presented
+/// pass acknowledges once.
 #[test]
 fn a_discarded_pass_does_not_acknowledge_or_lose_an_injected_batch() {
     let mut u = Ui::new(Session::empty());
@@ -565,6 +608,8 @@ fn a_discarded_pass_does_not_acknowledge_or_lose_an_injected_batch() {
     assert!(app.input_acks.is_empty() && app.applied_acks.is_empty());
 }
 
+/// Asserts injected text is applied once across a discarded sizing pass and acknowledged
+/// once.
 #[test]
 fn injected_text_lands_once_across_a_discarded_sizing_pass() {
     // egui reruns a discarded pass with the same `RawInput`. The custom editor applied the text in
diff --git a/crates/ui-egui/src/credits_tests.rs b/crates/ui-egui/src/credits_tests.rs
index 8b10a622..fb3993ad 100644
--- a/crates/ui-egui/src/credits_tests.rs
+++ b/crates/ui-egui/src/credits_tests.rs
@@ -51,10 +51,12 @@ impl Ui {
         u
     }
 
+    /// Store the About table's current view in test context data.
     fn set_view(&self, v: View) {
         self.ctx.data_mut(|d| d.insert_temp(egui::Id::unique("credits_view"), v));
     }
 
+    /// Read the stored About table view, defaulting when unset.
     fn view(&self) -> View {
         self.ctx.data(|d| d.get_temp::<View>(egui::Id::unique("credits_view"))).unwrap_or_default()
     }
diff --git a/crates/ui-egui/src/dialogs.rs b/crates/ui-egui/src/dialogs.rs
index 3ec562a2..8d4d8fdb 100644
--- a/crates/ui-egui/src/dialogs.rs
+++ b/crates/ui-egui/src/dialogs.rs
@@ -179,6 +179,10 @@ pub fn keys(app: &mut FigApp, ctx: &Context) {
     }
 }
 
+/// Draw the app's dialogs and cards: pending opens/imports/missing fonts, About,
+/// Preferences, shortcuts, find/replace, batch rename, menu input, variables, dev compare,
+/// branch, export preview, colour profile, plugin, live join/publish, online dialogs and
+/// close confirmation.
 pub fn show(app: &mut FigApp, ctx: &Context) {
     // Dropped files waiting to open: their card, then (once it has shown) the files.
     crate::pending_open::pending_opens(app, ctx);
diff --git a/crates/ui-egui/src/field_tests.rs b/crates/ui-egui/src/field_tests.rs
index 4e724553..341e7cca 100644
--- a/crates/ui-egui/src/field_tests.rs
+++ b/crates/ui-egui/src/field_tests.rs
@@ -467,6 +467,8 @@ fn lead(u: &Ui, id: Id) -> Pos2 {
     u.ctx.read_response(id.with("lead")).unwrap_or_else(|| panic!("no field {id:?}")).rect.center()
 }
 
+/// Asserts scrubbing the colour picker's R and alpha fields updates the colour live, each
+/// scrub adding one undo step.
 #[test]
 fn scrubbing_colour_picker_fields_is_live_and_one_undo_step() {
     let (mut u, a, _) = setup();
@@ -490,6 +492,8 @@ fn scrubbing_colour_picker_fields_is_live_and_one_undo_step() {
     assert_eq!(undo_steps(&u), steps + 2, "alpha");
 }
 
+/// Asserts scrubbing a prototype delay sets the value once when released and adds one undo
+/// step.
 #[test]
 fn scrubbing_a_prototype_delay_sets_it_once_when_let_go() {
     let mut s = Session::new();
@@ -514,6 +518,7 @@ fn scrubbing_a_prototype_delay_sets_it_once_when_let_go() {
     assert_eq!((ms, undo_steps(&u)), (800, steps + 1));
 }
 
+/// Asserts scrubbing the scale panel's width scales the layer live in one undo step.
 #[test]
 fn scrubbing_the_scale_panel_width_scales_live_in_one_undo_step() {
     let (mut u, a, _) = setup();
@@ -584,6 +589,8 @@ fn the_intensity_label_fits_whole_in_every_language() {
     out.textures_delta.clear();
 }
 
+/// Asserts a label too long for its number field is elided before the value, while the value
+/// stays whole and both remain inside the field.
 #[test]
 fn a_label_too_long_for_its_field_ends_in_an_ellipsis_before_the_value() {
     let ctx = egui::Context::default();
@@ -780,6 +787,8 @@ fn a_deferred_field_save_keeps_its_document_when_the_next_input_switches_tabs()
     }
 }
 
+/// Asserts a deferred field save does not retarget a closed, moved or foreign owner: the other
+/// file stays untouched, Save as is not opened, and the stale request is consumed once.
 #[test]
 fn a_deferred_field_save_does_not_retarget_a_closed_moved_or_foreign_owner() {
     for change in ["closed", "moved", "foreign"] {
diff --git a/crates/ui-egui/src/frame_labels.rs b/crates/ui-egui/src/frame_labels.rs
index 4c4b0de1..a87fc9f4 100644
--- a/crates/ui-egui/src/frame_labels.rs
+++ b/crates/ui-egui/src/frame_labels.rs
@@ -58,6 +58,9 @@ pub fn turn_since(painter: &Painter, from: ShapeIdx, pivot: Pos2, angle: f32) {
     });
 }
 
+/// Recursively rotate shape geometry by `rot`/`angle` about `pivot`: leaves
+/// no-op/callback/band shapes alone, rotates points and centers, adds the angle to
+/// ellipses/rects/text, and rotates meshes.
 fn turn(shape: &mut Shape, rot: Rot2, angle: f32, pivot: Pos2) {
     let at = |p: &mut Pos2| *p = pivot + rot * (*p - pivot);
     match shape {
diff --git a/crates/ui-egui/src/frame_presets.rs b/crates/ui-egui/src/frame_presets.rs
index 0d1c4b91..9eb28162 100644
--- a/crates/ui-egui/src/frame_presets.rs
+++ b/crates/ui-egui/src/frame_presets.rs
@@ -10,6 +10,8 @@ use crate::icons::{self, Icon};
 use crate::theme::{Tokens, regular, semibold};
 use crate::widgets::{self, PAD};
 
+/// Draw the expandable frame-preset categories; choosing a preset runs `frame.create`,
+/// switches to the Move tool and zooms to the new selection.
 pub fn panel(app: &mut FigApp, ui: &mut Ui) {
     let t = Tokens::get(ui.ctx());
     widgets::section_header(ui, tr("Frame"), &[], false);
diff --git a/crates/ui-egui/src/guides.rs b/crates/ui-egui/src/guides.rs
index 827597ac..3200ca42 100644
--- a/crates/ui-egui/src/guides.rs
+++ b/crates/ui-egui/src/guides.rs
@@ -49,6 +49,7 @@ struct Placed {
     line: Option<[Point; 2]>,
 }
 
+/// Stable egui id for guide dragging.
 fn drag_id() -> Id {
     Id::unique("guide_drag")
 }
diff --git a/crates/ui-egui/src/handles.rs b/crates/ui-egui/src/handles.rs
index b7a575fa..d29d59ee 100644
--- a/crates/ui-egui/src/handles.rs
+++ b/crates/ui-egui/src/handles.rs
@@ -67,6 +67,7 @@ fn crop_corners(app: &FigApp, id: NodeId, r: (f64, f64, f64, f64)) -> Option<[Po
     ])
 }
 
+/// Stable egui id for handle dragging.
 fn drag_id() -> Id {
     Id::unique("figcraft_handle_drag")
 }
diff --git a/crates/ui-egui/src/home.rs b/crates/ui-egui/src/home.rs
index ebea682e..9c809b99 100644
--- a/crates/ui-egui/src/home.rs
+++ b/crates/ui-egui/src/home.rs
@@ -188,6 +188,8 @@ fn dropped(app: &mut FigApp, ctx: &egui::Context) {
     }
 }
 
+/// Draw the Home sidebar: app icon and wordmark, file/template search (Escape clears it)
+/// and section tabs; choosing a section clears the file query.
 fn sidebar(app: &mut FigApp, ui: &mut Ui, t: &Tokens, left: Rect) {
     let mut y = left.min.y + 20.0;
     crate::theme::paint_app_icon(ui, Rect::from_min_size(pos2(left.min.x + 12.0, y - 4.0), vec2(32.0, 32.0)));
@@ -475,6 +477,8 @@ fn matches(template: &Template, query: &str, kind: Option<Kind>) -> bool {
             || has(template.size))
 }
 
+/// Draw template search and kind filter, show no-match guidance and a "Show all templates"
+/// button that clears the query and kind, and lay matching templates out in a grid.
 fn templates(app: &mut FigApp, ui: &mut Ui, t: &Tokens) {
     heading(ui, t, tr("Templates"));
     ui.horizontal(|ui| {
diff --git a/crates/ui-egui/src/idle_tests.rs b/crates/ui-egui/src/idle_tests.rs
index cc19d6a9..ee25124a 100644
--- a/crates/ui-egui/src/idle_tests.rs
+++ b/crates/ui-egui/src/idle_tests.rs
@@ -248,6 +248,8 @@ fn a_finished_background_render_wakes_the_ui() {
     assert!(worker.poll().is_some(), "the woken frame finds the image");
 }
 
+/// Asserts a control request wakes an idle UI and is answered, and screenshots keep frames
+/// coming until delivered before the UI rests again.
 #[test]
 fn control_requests_and_screenshots_wake_an_idle_ui() {
     let (mut h, _) = document();
@@ -341,6 +343,8 @@ fn cjk_names_are_looked_for_in_edits_not_on_every_pan() {
     assert_eq!(h.app.cjk_needed(&ctx, 0), crate::cjk::HANGUL);
 }
 
+/// Asserts a hidden window answers edits and inspection at once, while a screenshot is
+/// parked with a deadline and times out once instead of waiting for a frame.
 #[test]
 fn a_hidden_window_answers_at_once() {
     // #269, #720: minimised or covered, the window draws no frames, but the app's logic still runs:
@@ -424,6 +428,8 @@ fn auto_save_writes_a_changed_file_then_rests() {
     let _ = std::fs::remove_dir_all(&dir);
 }
 
+/// Asserts a hidden logic tick runs background work and advances the autosave deadline
+/// without counting a UI frame, and is idempotent at the same time.
 #[test]
 fn a_hidden_logic_tick_runs_background_work_but_counts_no_ui_frame() {
     let (mut h, _) = document();
@@ -444,6 +450,7 @@ fn a_hidden_logic_tick_runs_background_work_but_counts_no_ui_frame() {
     assert_eq!(h.app.ui.next_autosave, deadline, "idempotent at the same monotonic time");
 }
 
+/// Asserts a discarded sizing pass counts one drawn frame, not one per pass.
 #[test]
 fn a_discarded_sizing_pass_sets_up_and_counts_one_frame_only() {
     let (mut h, _) = document();
diff --git a/crates/ui-egui/src/ime_tests.rs b/crates/ui-egui/src/ime_tests.rs
index e699dda5..e6c2f698 100644
--- a/crates/ui-egui/src/ime_tests.rs
+++ b/crates/ui-egui/src/ime_tests.rs
@@ -48,6 +48,7 @@ fn ime_descriptor(u: &mut Ui, events: Vec<Event>) -> IMEOutput {
     u.frame_raw(RawInput { events, ..Default::default() }).platform_output.ime.expect("the IME stays on while editing")
 }
 
+/// Return the available surrounding-text payload of an IME output, panicking when unavailable.
 fn available(ime: &IMEOutput) -> &IMESurroundingTextPayload {
     match &ime.surrounding_text {
         IMESurroundingText::Available(payload) => payload,
@@ -55,6 +56,7 @@ fn available(ime: &IMEOutput) -> &IMESurroundingTextPayload {
     }
 }
 
+/// Create a text layer with `text` and return its node id.
 fn text_layer(s: &mut Session, text: &str) -> NodeId {
     NodeId(s.execute("text.create", &json!({"text": text, "x": 40, "y": 40})).unwrap()["id"].as_u64().unwrap())
 }
@@ -103,6 +105,8 @@ fn pinyin_composes_inline_and_commits_once_with_the_ime_on_every_frame() {
     assert_eq!(text(&u, t), "Hi你好\n!");
 }
 
+/// Asserts an empty IME commit ends the composition, inserts nothing, keeps the editor
+/// focused, and the next pass observes the committed text.
 #[test]
 fn an_empty_ime_commit_ends_the_composition_without_inserting_text() {
     // Safari's egui web integration sends `Commit("")` (not `Preedit("")`) when the last
@@ -126,6 +130,8 @@ fn an_empty_ime_commit_ends_the_composition_without_inserting_text() {
     assert_eq!(text(&u, t), "Hello");
 }
 
+/// Asserts byte deletion before the paired commit replaces the exact UTF-8 range, and one undo
+/// restores the pre-IME text.
 #[test]
 fn an_ime_replacing_text_deletes_in_bytes_before_the_paired_commit() {
     // 0.37 sends `DeleteSurroundingBytes` immediately before the commit that replaces it. The
@@ -146,6 +152,8 @@ fn an_ime_replacing_text_deletes_in_bytes_before_the_paired_commit() {
     assert_eq!(text(&u, t), "ab\u{4F60}\u{597D}cd", "one undo restores the pre-IME text");
 }
 
+/// Asserts a caret click invalidates the whole stale IME batch (both byte and character
+/// deletions) while a later direct commit still works.
 #[test]
 fn a_caret_click_rejects_the_stale_delete_and_commit_in_the_same_input_batch() {
     figcraft_text::scan_system_fonts();
@@ -185,6 +193,8 @@ fn a_caret_click_rejects_the_stale_delete_and_commit_in_the_same_input_batch() {
     }
 }
 
+/// Asserts a control-channel document switch rejects the old composition's delete and commit
+/// batch, while a direct commit to the new target remains valid.
 #[test]
 fn a_document_switch_rejects_the_old_compositions_delete_and_commit_batch() {
     figcraft_text::scan_system_fonts();
@@ -214,6 +224,8 @@ fn a_document_switch_rejects_the_old_compositions_delete_and_commit_batch() {
     assert_eq!(text(&u, b), "BravoX", "a direct commit to the new noncomposing target remains valid");
 }
 
+/// Asserts the first observation and ordinary typing are `Other`, while an accepted commit is
+/// `InputMethod` with UTF-8 offsets, the same owner and generation.
 #[test]
 fn ime_cause_is_input_method_only_for_an_accepted_commit() {
     figcraft_text::scan_system_fonts();
@@ -240,6 +252,8 @@ fn ime_cause_is_input_method_only_for_an_accepted_commit() {
     assert_eq!(text(&u, t), "Hi你好x");
 }
 
+/// Asserts a frame mixing IME and application edits is `Other`, and a later pure commit is
+/// `InputMethod` without lingering state.
 #[test]
 fn ime_cause_reports_mixed_application_and_ime_mutations_as_other() {
     figcraft_text::scan_system_fonts();
@@ -267,6 +281,7 @@ fn ime_cause_reports_mixed_application_and_ime_mutations_as_other() {
     assert_eq!(text(&u, t), "Hiあbうcえおdか");
 }
 
+/// Asserts a control-channel text edit is an application change (`Other`).
 #[test]
 fn a_control_channel_text_edit_is_an_application_change() {
     figcraft_text::scan_system_fonts();
@@ -283,6 +298,8 @@ fn a_control_channel_text_edit_is_an_application_change() {
     assert_eq!(available(&out).text, "Hiz");
 }
 
+/// Asserts a byte delete followed by a commit is `InputMethod` and describes the
+/// post-mutation text and caret.
 #[test]
 fn ime_delete_then_commit_is_input_method_and_describes_the_post_mutation_text() {
     figcraft_text::scan_system_fonts();
@@ -302,6 +319,8 @@ fn ime_delete_then_commit_is_input_method_and_describes_the_post_mutation_text()
     assert_eq!(text(&u, t), "abXd");
 }
 
+/// Asserts preedit text is excluded from surrounding text and earns no receipt, while the
+/// following commit is `InputMethod`.
 #[test]
 fn preedit_is_not_surrounding_text_but_the_commit_that_follows_is_input_method() {
     figcraft_text::scan_system_fonts();
@@ -322,6 +341,8 @@ fn preedit_is_not_surrounding_text_but_the_commit_that_follows_is_input_method()
     assert_eq!(available(&committed).cursor, 8);
 }
 
+/// Asserts surrounding text is logical UTF-8 with byte offsets and keeps a reversed
+/// selection.
 #[test]
 fn ime_surrounding_text_is_logical_utf8_and_keeps_a_reversed_selection() {
     figcraft_text::scan_system_fonts();
@@ -339,6 +360,8 @@ fn ime_surrounding_text_is_logical_utf8_and_keeps_a_reversed_selection() {
     assert!(payload.cursor < payload.anchor, "the reversed selection is not sorted");
 }
 
+/// Asserts empty text is available while a selection wider than the 4000-byte budget is
+/// explicitly unavailable but still has a nonzero IME context generation.
 #[test]
 fn empty_text_is_available_while_a_too_wide_selection_is_explicitly_unavailable() {
     figcraft_text::scan_system_fonts();
@@ -361,6 +384,7 @@ fn empty_text_is_available_while_a_too_wide_selection_is_explicitly_unavailable(
     assert!(wide.context_generation > 0, "the owner stays known when only the text is unavailable");
 }
 
+/// Asserts replacing a too-wide selection with a commit is still an `InputMethod` receipt.
 #[test]
 fn a_commit_replacing_a_too_wide_selection_is_still_an_input_method_receipt() {
     figcraft_text::scan_system_fonts();
@@ -382,6 +406,8 @@ fn a_commit_replacing_a_too_wide_selection_is_still_an_input_method_receipt() {
     assert_eq!((available(&out).cursor, available(&out).anchor), (1, 1));
 }
 
+/// Asserts another text node is another owner, and re-entering the same node changes the
+/// context generation while keeping the owner key.
 #[test]
 fn a_new_edit_session_and_another_text_node_are_new_ime_owners() {
     figcraft_text::scan_system_fonts();
@@ -405,6 +431,8 @@ fn a_new_edit_session_and_another_text_node_are_new_ime_owners() {
     assert_ne!(again.context_generation, first.context_generation, "re-entering is a replaced target");
 }
 
+/// Asserts an accepted commit survives a discarded rerun without inserting twice and keeps
+/// its `InputMethod` cause, while a mixed rerun is `Other`.
 #[test]
 fn an_accepted_commit_survives_a_discarded_pass_without_reapplying_or_losing_its_cause() {
     figcraft_text::scan_system_fonts();
@@ -428,6 +456,9 @@ fn an_accepted_commit_survives_a_discarded_pass_without_reapplying_or_losing_its
     assert_eq!(mixed.change_cause, ImeChangeCause::Other);
 }
 
+/// Asserts IME context state is scoped per viewport: each viewport has its own generation,
+/// the root keeps its context across an aux pass, and a closed aux viewport does not inherit
+/// the old generation.
 #[test]
 fn ime_context_state_is_scoped_per_viewport() {
     figcraft_text::scan_system_fonts();
@@ -480,6 +511,7 @@ fn ime_context_state_is_scoped_per_viewport() {
     assert_ne!(aux_again.context_generation, aux_ime.context_generation);
 }
 
+/// Asserts the engine's IME surrounding-text byte limit equals egui's wire limit.
 #[test]
 fn the_engine_surrounding_limit_matches_the_wire_limit() {
     // A divergence would truncate or overrun the bounded payload silently.
@@ -488,6 +520,8 @@ fn the_engine_surrounding_limit_matches_the_wire_limit() {
     assert_eq!(engine, wire);
 }
 
+/// Asserts a frame observes the IME exactly once in both the editor pass and the Home
+/// early-return pass.
 #[test]
 fn a_frame_observes_the_ime_once_even_when_it_ends_early() {
     figcraft_text::scan_system_fonts();
@@ -506,6 +540,8 @@ fn a_frame_observes_the_ime_once_even_when_it_ends_early() {
     assert_eq!(u.app.ime_observations - before, 1, "one idle observation on the home screen");
 }
 
+/// Asserts a double-click inside an existing edit selects the word without changing the IME
+/// owner or generation.
 #[test]
 fn a_double_click_inside_the_edit_keeps_the_ime_generation() {
     figcraft_text::scan_system_fonts();
@@ -536,6 +572,8 @@ fn a_double_click_inside_the_edit_keeps_the_ime_generation() {
     assert_eq!(available(&after).text, "Hello world");
 }
 
+/// Asserts a `window.new` that moves the edited file leaves the root window emitting no IME
+/// descriptor.
 #[test]
 fn a_window_new_that_moves_the_edited_file_leaves_the_root_ime_idle() {
     figcraft_text::scan_system_fonts();
@@ -560,6 +598,8 @@ fn a_window_new_that_moves_the_edited_file_leaves_the_root_ime_idle() {
     assert!(out.platform_output.ime.is_none(), "the root must not emit a descriptor for a file it no longer shows");
 }
 
+/// Asserts a CRLF-normalized commit is application-origin (`Other`), and bare-newline and
+/// control-only commits insert nothing.
 #[test]
 fn a_transformed_commit_is_application_origin_and_a_bare_newline_does_nothing() {
     figcraft_text::scan_system_fonts();
@@ -582,6 +622,8 @@ fn a_transformed_commit_is_application_origin_and_a_bare_newline_does_nothing()
     assert!(matches!(control.surrounding_text, IMESurroundingText::Available(_)));
 }
 
+/// Asserts character deletion keeps the selection for the paired commit, which replaces it
+/// and reports `InputMethod`.
 #[test]
 fn ime_delete_surrounding_chars_keeps_the_selection_for_the_paired_commit() {
     figcraft_text::scan_system_fonts();
diff --git a/crates/ui-egui/src/layers.rs b/crates/ui-egui/src/layers.rs
index 42a9569e..0ce4fa7a 100644
--- a/crates/ui-egui/src/layers.rs
+++ b/crates/ui-egui/src/layers.rs
@@ -134,6 +134,8 @@ pub fn rail(app: &mut FigApp, ui: &mut Ui) {
     }
 }
 
+/// Draw the left panel: versions when open, otherwise the file/Assets header with in-place
+/// file rename and collapse control, followed by Pages and Layers or the Assets panel.
 pub fn left_panel(app: &mut FigApp, ui: &mut Ui) {
     if app.ui.versions.open {
         crate::versions::panel(app, ui);
@@ -173,6 +175,8 @@ pub fn left_panel(app: &mut FigApp, ui: &mut Ui) {
     }
 }
 
+/// Draw the page list with open/search/add controls, filtering, selection, rename,
+/// reorder/drag and layer drop-to-page; Dev Mode allows opening pages but blocks mutations.
 fn pages(app: &mut FigApp, ui: &mut Ui) {
     let t = Tokens::get(ui.ctx());
     // Dev Mode only inspects: rows open pages, but don't add, rename, reorder, duplicate or delete.
@@ -444,6 +448,7 @@ struct Sweep {
     ids: Vec<NodeId>,
 }
 
+/// Stable egui id for the eye/padlock sweep state.
 fn sweep_id() -> Id {
     Id::unique("layer_toggle_sweep")
 }
@@ -654,6 +659,7 @@ fn rename_layer(app: &mut FigApp, id: NodeId) {
     app.ui.layers_seen_sel = app.session.selection();
 }
 
+/// Stable egui id for a layer row's rename field.
 fn rename_id(id: NodeId) -> Id {
     Id::unique(("rename", id))
 }
@@ -722,6 +728,8 @@ fn search_field(ui: &mut Ui, t: &Tokens, w: f32, id: Id, hint: &str, text: &mut
     }
 }
 
+/// Draw the layer tree with search, cached rows, reveal-selection expansion and scrolling,
+/// rename/Tab navigation, selection and drag/drop, sweep toggles and Dev Mode restrictions.
 fn layers(app: &mut FigApp, ui: &mut Ui) {
     let t = Tokens::get(ui.ctx());
     // Dev Mode only inspects: rows select and expand, but don't rename, reorder, hide or lock.
diff --git a/crates/ui-egui/src/layers_behaviour_tests.rs b/crates/ui-egui/src/layers_behaviour_tests.rs
index e801ad00..0f312499 100644
--- a/crates/ui-egui/src/layers_behaviour_tests.rs
+++ b/crates/ui-egui/src/layers_behaviour_tests.rs
@@ -312,6 +312,7 @@ fn pages_down_to(u: &mut Ui, to: f32) -> Vec<NodeId> {
     opened
 }
 
+/// Asserts a 60-page list scrolls with the wheel to its last page, past its first pages.
 #[test]
 fn a_long_pages_list_scrolls_and_leaves_room_for_the_layers() {
     let mut s = Session::new();
@@ -383,6 +384,8 @@ fn double_click_checking_focus(u: &mut Ui, p: Pos2) {
     }
 }
 
+/// Asserts double-clicking a page selects and renames it, with the keyboard in its name
+/// field for the screen-reader tree.
 #[test]
 fn double_clicking_a_page_renames_it_with_the_focus_in_the_screen_reader_tree() {
     let mut s = Session::new();
diff --git a/crates/ui-egui/src/layers_rename_tests.rs b/crates/ui-egui/src/layers_rename_tests.rs
index 6ffa9696..c1c229eb 100644
--- a/crates/ui-egui/src/layers_rename_tests.rs
+++ b/crates/ui-egui/src/layers_rename_tests.rs
@@ -144,6 +144,8 @@ fn rename_without_a_name_renames_one_row_or_opens_the_dialog() {
     assert!(std::sync::Arc::ptr_eq(&doc, &s.ds().unwrap().doc));
 }
 
+/// Asserts a layer rename continues after its row is scrolled out of view and commits on
+/// Enter.
 #[test]
 fn a_rename_scrolled_out_of_view_goes_on() {
     let mut s = Session::new();
diff --git a/crates/ui-egui/src/layout_panel.rs b/crates/ui-egui/src/layout_panel.rs
index eef37755..0874da2f 100644
--- a/crates/ui-egui/src/layout_panel.rs
+++ b/crates/ui-egui/src/layout_panel.rs
@@ -283,6 +283,8 @@ fn add_slot(ui: &mut Ui, label: &str, tip: &str, width: f32) -> egui::Response {
     resp
 }
 
+/// Draw the 3×3 main/cross alignment grid, auto-gap modes, grid column/row gaps and the
+/// horizontal baseline checkbox.
 fn alignment(app: &mut FigApp, ui: &mut Ui, ids: &[NodeId], l: &AutoLayout) {
     let t = Tokens::get(ui.ctx());
     let grid_mode = l.mode == LayoutMode::Grid;
diff --git a/crates/ui-egui/src/lib.rs b/crates/ui-egui/src/lib.rs
index d3c17453..6f0effd8 100644
--- a/crates/ui-egui/src/lib.rs
+++ b/crates/ui-egui/src/lib.rs
@@ -488,6 +488,7 @@ pub struct FrameClock {
 }
 
 impl Default for FrameClock {
+    /// Start the frame clock at the current web time with no injected test time.
     fn default() -> Self {
         Self { origin: web_time::Instant::now(), test_now: None }
     }
@@ -722,6 +723,9 @@ pub struct UiState {
 }
 
 impl Default for UiState {
+    /// Seed the default UI state (panel widths, tabs, pages, Home, presenters, pickers and
+    /// dialogs off, and the rest of the transient UI fields); `FigApp::new` overrides panel
+    /// widths and the pages height from preferences.
     fn default() -> Self {
         Self {
             left_width: PANEL_DEFAULT,
@@ -915,6 +919,9 @@ pub struct FigApp {
 pub type Done = Box<dyn FnOnce(&mut FigApp, &egui::Context, Value)>;
 
 impl FigApp {
+    /// Construct `FigApp` from a session and services, taking panel widths and pages height
+    /// from preferences and initializing UI, canvas, clocks, capture/IME and transient channel
+    /// state.
     pub fn new(session: Session, services: Box<dyn Services>) -> Self {
         // The main window's panels open as wide as they were left.
         let (left_width, right_width) = session.prefs.panel_widths;
@@ -2044,6 +2051,9 @@ impl FigApp {
         }
     }
 
+    /// Draw the toast: start its lifetime on the frame **after** the first drawn frame, request
+    /// that frame and the frame that hides it, expire and remove it at the deadline, and place it
+    /// at the bottom centre.
     fn toast_ui(&mut self, ctx: &egui::Context) {
         let Some((msg, clock)) = &mut self.ui.toast else { return };
         let now = ctx.input(|i| i.time);
diff --git a/crates/ui-egui/src/live_join_tests.rs b/crates/ui-egui/src/live_join_tests.rs
index 81eddc76..bc1db8ad 100644
--- a/crates/ui-egui/src/live_join_tests.rs
+++ b/crates/ui-egui/src/live_join_tests.rs
@@ -14,6 +14,7 @@ fn escape(h: &mut Harness) {
     }
 }
 
+/// Whether the Join link field currently has focus.
 fn link_focused(h: &Harness) -> bool {
     h.ctx.memory(|m| m.has_focus(egui::Id::unique("live_join_link")))
 }
diff --git a/crates/ui-egui/src/live_server_tests.rs b/crates/ui-egui/src/live_server_tests.rs
index 0bf1e631..014be152 100644
--- a/crates/ui-egui/src/live_server_tests.rs
+++ b/crates/ui-egui/src/live_server_tests.rs
@@ -20,6 +20,7 @@ fn key(h: &mut Harness, key: Key) {
     }
 }
 
+/// Whether the widget with the given id currently has focus.
 fn focused(h: &Harness, id: &str) -> bool {
     h.ctx.memory(|m| m.has_focus(egui::Id::unique(id)))
 }
diff --git a/crates/ui-egui/src/live_share_tests.rs b/crates/ui-egui/src/live_share_tests.rs
index 06d902bd..d7fc61c8 100644
--- a/crates/ui-egui/src/live_share_tests.rs
+++ b/crates/ui-egui/src/live_share_tests.rs
@@ -385,6 +385,9 @@ fn without_a_code_the_link_is_shared_instead() {
     assert_eq!(script.lock().unwrap().copied.last().map(String::as_str), Some(PLAIN));
 }
 
+/// Asserts the join field accepts a typed code or invite link, joins on Enter, clears after
+/// joining, shows failure/retry, rejects an invalid code with an error, and accepts local
+/// codes and links.
 #[test]
 fn the_join_field_takes_a_code_or_a_link_and_enter_joins() {
     let (mut h, script) = harness();
@@ -450,6 +453,8 @@ fn the_home_screen_joins_with_a_code_and_opens_the_file() {
     assert_eq!(h.app.session.docs.len(), 2);
 }
 
+/// Asserts the join dialog uses the same shared join field, focuses it, and closes once the
+/// join starts.
 #[test]
 fn the_join_dialog_is_the_same_field() {
     let (mut h, script) = harness();
diff --git a/crates/ui-egui/src/live_tests.rs b/crates/ui-egui/src/live_tests.rs
index eaff7354..63c3c42a 100644
--- a/crates/ui-egui/src/live_tests.rs
+++ b/crates/ui-egui/src/live_tests.rs
@@ -290,6 +290,8 @@ fn cursors_follow_pages_in_a_shared_document() {
     assert_eq!(h.app.ui.toast.as_ref().map(|t| t.0.as_str()), Some("Hana left"));
 }
 
+/// Asserts clicking a peer's avatar follows that peer, and Escape or scrolling the canvas
+/// stops following.
 #[test]
 fn clicking_an_avatar_follows_and_escape_stops() {
     let (mut h, _) = Harness::new();
diff --git a/crates/ui-egui/src/menu_aim_tests.rs b/crates/ui-egui/src/menu_aim_tests.rs
index ed167e12..6f7c4b8a 100644
--- a/crates/ui-egui/src/menu_aim_tests.rs
+++ b/crates/ui-egui/src/menu_aim_tests.rs
@@ -87,6 +87,7 @@ impl Ui {
 
 const TOPS: [&str; 6] = ["File", "Edit", "View", "Object", "Text", "Arrange"];
 
+/// Stable id for a top-level menu in the menu-aim test harness.
 fn top(name: &str) -> Id {
     Id::unique(("menu", name))
 }
@@ -145,6 +146,8 @@ fn a_reopened_main_menu_shows_no_stale_submenu() {
     assert!(u.tops_shown().is_empty(), "reopened with {:?} open", u.tops_shown());
 }
 
+/// Asserts leaving a top menu and returning to it does not restore the submenu that was open
+/// before.
 #[test]
 fn a_submenu_one_level_down_reopens_closed() {
     let mut u = Ui::new();
diff --git a/crates/ui-egui/src/menu_input_tests.rs b/crates/ui-egui/src/menu_input_tests.rs
index a50173bc..6fc65533 100644
--- a/crates/ui-egui/src/menu_input_tests.rs
+++ b/crates/ui-egui/src/menu_input_tests.rs
@@ -69,6 +69,8 @@ fn batch_rename_opens_its_existing_dialog() {
     assert!(ui.app.ui.last_error.is_none());
 }
 
+/// Asserts `file.rename` opens the left panel's inline file-name editor (not a dialog),
+/// focuses it, and commits the typed name on Enter.
 #[test]
 fn rename_file_edits_the_file_name_in_place() {
     let mut ui = Ui::new(Session::new());
diff --git a/crates/ui-egui/src/menus.rs b/crates/ui-egui/src/menus.rs
index e73d242d..e5ddb899 100644
--- a/crates/ui-egui/src/menus.rs
+++ b/crates/ui-egui/src/menus.rs
@@ -478,10 +478,12 @@ struct At {
     path: String,
 }
 
+/// Scoped egui id for the current menu level.
 fn at_key(ui: &Ui) -> Id {
     ui.scope_id().with("menu_level")
 }
 
+/// Return the current menu root/path, defaulting to the main menu root.
 fn level_at(ui: &Ui) -> At {
     ui.data(|d| d.get_temp::<At>(at_key(ui))).unwrap_or(At { root: Id::unique("menus"), path: String::new() })
 }
@@ -817,6 +819,9 @@ const TOP_MENUS: &[&str] = &[
     tr_noop("Help"),
 ];
 
+/// Draw the main and context menu trees: forget closed/stale submenu state, apply
+/// control-channel Select-layer open/close, close on outside click or Escape, then draw the
+/// colour picker and palette popups.
 pub fn popups(app: &mut FigApp, ctx: &egui::Context) {
     let t = Tokens::get(ctx);
     // A closed menu forgets its open submenus (and a context menu opened somewhere else starts
@@ -1020,6 +1025,7 @@ pub fn popups(app: &mut FigApp, ctx: &egui::Context) {
 /// The context menu's Select layer submenu (its key in the context menu's tree).
 const SELECT_LAYER: &str = "Select layer";
 
+/// Stable egui id for the context menu's pending Select-layer open request.
 fn select_layer_ask_id() -> Id {
     Id::unique("ctx_select_layer_ask")
 }
diff --git a/crates/ui-egui/src/panel_remove_tests.rs b/crates/ui-egui/src/panel_remove_tests.rs
index a2e8d3ee..1608902d 100644
--- a/crates/ui-egui/src/panel_remove_tests.rs
+++ b/crates/ui-egui/src/panel_remove_tests.rs
@@ -64,10 +64,13 @@ fn remove_button(u: &mut Ui, list: &str, index: usize) -> Pos2 {
         .unwrap_or_else(|| panic!("no Remove button in {list} row {index} {row:?} {all:?}"))
 }
 
+/// Read a temporary boolean open-settings flag keyed by `salt` and row index.
 fn flag(u: &Ui, salt: &'static str, i: usize) -> bool {
     u.ctx.data(|d| d.get_temp::<bool>(Id::unique((salt, i)))).unwrap_or(false)
 }
 
+/// Asserts removing a fill keeps the open picker on the surviving paint (with its index
+/// shifted), and removing the paint being edited closes the picker.
 #[test]
 fn removing_a_fill_keeps_the_picker_on_its_paint() {
     let mut s = Session::new();
@@ -93,6 +96,8 @@ fn removing_a_fill_keeps_the_picker_on_its_paint() {
     assert_eq!(u.app.ui.picker, None);
 }
 
+/// Asserts removing effects or grids moves open settings and an open colour picker to the
+/// surviving row, or closes them when their own row is removed.
 #[test]
 fn removing_effects_and_grids_keeps_open_settings_with_their_rows() {
     let mut s = Session::new();
diff --git a/crates/ui-egui/src/panel_reorder_tests.rs b/crates/ui-egui/src/panel_reorder_tests.rs
index 54caa687..ffeb948e 100644
--- a/crates/ui-egui/src/panel_reorder_tests.rs
+++ b/crates/ui-egui/src/panel_reorder_tests.rs
@@ -73,6 +73,8 @@ fn escape_cancels_a_row_drag() {
     assert_eq!(u.app.session.ds().unwrap().selection, [r], "the Escape only cancels the drag");
 }
 
+/// Asserts effect and layout-grid rows reorder by drag, while a mixed fill list exposes no
+/// drag handle.
 #[test]
 fn effects_and_grids_drag_too_and_mixed_lists_dont() {
     let (mut u, r) = setup();
diff --git a/crates/ui-egui/src/perf_tests.rs b/crates/ui-egui/src/perf_tests.rs
index 7b5d1212..eba5e68c 100644
--- a/crates/ui-egui/src/perf_tests.rs
+++ b/crates/ui-egui/src/perf_tests.rs
@@ -68,6 +68,8 @@ impl Bench {
     }
 }
 
+/// Build and print a synthetic UI benchmark report for the given layer count; it makes no
+/// assertions.
 fn report(layers: usize) {
     let mut b = Bench::new(layers);
     let mut rows: Vec<(&str, f64)> = Vec::new();
@@ -180,6 +182,7 @@ fn design_system(icons: usize, instances: usize) -> (Document, figcraft_engine::
     figcraft_engine::synthetic_ds::design_system_with_instances(&spec, instances).unwrap()
 }
 
+/// Build a test mouse-wheel event for the given vertical delta.
 fn wheel(d: f32) -> Event {
     Event::MouseWheel {
         unit: egui::MouseWheelUnit::Point,
diff --git a/crates/ui-egui/src/plugin_panel_tests.rs b/crates/ui-egui/src/plugin_panel_tests.rs
index 3b0f2746..53b1ba56 100644
--- a/crates/ui-egui/src/plugin_panel_tests.rs
+++ b/crates/ui-egui/src/plugin_panel_tests.rs
@@ -89,6 +89,9 @@ fn an_open_plugin_panel_draws_no_frames_while_idle() {
     Harness::new(session()).assert_idle("a plugin panel");
 }
 
+/// Asserts a plugin colour field's swatch opens the picker on that field, a picked colour
+/// reaches the plugin, and a second plugin's panel opens while the first remains (two panels
+/// present).
 #[test]
 fn a_colour_field_opens_the_colour_picker_and_two_panels_show_side_by_side() {
     let mut u = Ui::new(session());
diff --git a/crates/ui-egui/src/plugins_ui.rs b/crates/ui-egui/src/plugins_ui.rs
index 83295359..26479c4d 100644
--- a/crates/ui-egui/src/plugins_ui.rs
+++ b/crates/ui-egui/src/plugins_ui.rs
@@ -245,6 +245,9 @@ const INSTALL: &str = "plugin.directory.install";
 const MANAGE_W: f32 = 400.0;
 const ROW_TEXT_W: f32 = 300.0;
 
+/// Draw the Plugins window with installed and browse tabs, dispatching remove, import,
+/// browse, confirm and stop actions; closing the window cancels its directory requests and
+/// clears confirmation.
 fn manage_window(app: &mut FigApp, ctx: &Context) {
     let t = Tokens::get(ctx);
     let mut open = true;
@@ -509,6 +512,8 @@ fn summary(p: &InstalledPlugin) -> String {
     parts.join(" · ")
 }
 
+/// Draw a plugin command's parameter form: close it when the plugin or command disappeared,
+/// edit values and colour picks, run `plugin.run` on Run, and close on Cancel.
 fn form_window(app: &mut FigApp, ctx: &Context) {
     let Some(mut form) = app.ui.plugin_form.clone() else { return };
     let Some((name, command)) = app
diff --git a/crates/ui-egui/src/present_tests.rs b/crates/ui-egui/src/present_tests.rs
index 4679c15d..93729922 100644
--- a/crates/ui-egui/src/present_tests.rs
+++ b/crates/ui-egui/src/present_tests.rs
@@ -137,6 +137,8 @@ fn preview_pane_opens_follows_edits_and_the_selection() {
     assert!(u.app.ui.preview.is_none());
 }
 
+/// Asserts the preview's device viewport and scroll range, wheel and drag scrolling, the
+/// end clamp with spring-back, and that navigation resets scroll to the top.
 #[test]
 fn the_frame_scrolls_on_the_device_screen_by_wheel_and_drag() {
     let (mut u, a, b, _) = setup();
diff --git a/crates/ui-egui/src/present_view_tests.rs b/crates/ui-egui/src/present_view_tests.rs
index 97fbba03..361a4caf 100644
--- a/crates/ui-egui/src/present_view_tests.rs
+++ b/crates/ui-egui/src/present_view_tests.rs
@@ -135,6 +135,8 @@ fn num(v: &Value) -> f64 {
     v.as_f64().unwrap()
 }
 
+/// Asserts presenter fit/fit-width/fill/actual scaling, pan ranges, wheel and drag panning,
+/// option carry-over to the next presentation, and R restarting the flow.
 #[test]
 fn presenter_scales_by_its_options_and_pans_what_overflows() {
     let (mut u, big) = big();
@@ -272,6 +274,7 @@ fn scrolling_keeps_its_momentum_and_springs_back_from_the_ends() {
     assert_eq!(u.preview()["flinging"], json!(false));
 }
 
+/// Asserts wheel momentum continues after input stops and then comes to rest.
 #[test]
 fn the_wheel_coasts_after_it_stops() {
     let (mut u, a, ..) = setup();
diff --git a/crates/ui-egui/src/proto_canvas.rs b/crates/ui-egui/src/proto_canvas.rs
index 1faba513..b5d402b4 100644
--- a/crates/ui-egui/src/proto_canvas.rs
+++ b/crates/ui-egui/src/proto_canvas.rs
@@ -20,6 +20,7 @@ struct Drag {
     pos: Pos2,
 }
 
+/// Stable egui id for prototype connection dragging.
 fn drag_id() -> Id {
     Id::unique("proto_canvas_drag")
 }
@@ -59,6 +60,8 @@ struct Sources {
     ids: Arc<Vec<NodeId>>,
 }
 
+/// Return the cached subtree nodes with interactions for `page`, recomputing only when the
+/// document pointer or page changes.
 pub(crate) fn sources(ctx: &egui::Context, doc: &Arc<Document>, page: NodeId) -> Arc<Vec<NodeId>> {
     ctx.data_mut(|d| {
         let c = d.get_temp_mut_or_default::<Sources>(Id::unique("proto_canvas_sources"));
diff --git a/crates/ui-egui/src/proto_editor.rs b/crates/ui-egui/src/proto_editor.rs
index cc3c352b..7163807e 100644
--- a/crates/ui-egui/src/proto_editor.rs
+++ b/crates/ui-egui/src/proto_editor.rs
@@ -129,6 +129,7 @@ fn unavailable(label: &str) -> &'static str {
     }
 }
 
+/// Stable egui id for a node interaction's open action path.
 fn open_id(cx: &Cx) -> Id {
     Id::unique(("proto_open_action", cx.node, cx.k))
 }
diff --git a/crates/ui-egui/src/proto_editor_tests.rs b/crates/ui-egui/src/proto_editor_tests.rs
index e6838a0a..63c152e1 100644
--- a/crates/ui-egui/src/proto_editor_tests.rs
+++ b/crates/ui-egui/src/proto_editor_tests.rs
@@ -78,6 +78,9 @@ fn condition(u: &Ui, btn: NodeId, block: usize) -> String {
     blocks[block].condition.as_ref().map(|c| c.display(&doc.variables)).unwrap_or_default()
 }
 
+/// Asserts the interaction editor shows conditional blocks and nested actions, restarts a
+/// condition when a variable of another type is picked, ignores a right-hand-side variable pick
+/// for a complex condition, and one undo restores the previous condition.
 #[test]
 fn the_interaction_editor_shows_conditionals_and_picks_their_variables() {
     let (mut s, _, b, btn) = setup();
@@ -154,6 +157,8 @@ fn the_builder_takes_variable_operator_value_conditions() {
     }
 }
 
+/// Asserts invalid typed conditions keep their draft and show errors without saving, a valid
+/// one clears the error and saves, and Enter does not leak to shortcuts.
 #[test]
 fn typed_conditions_are_checked_and_errors_show_until_fixed() {
     let (mut s, _, b, btn) = setup();
diff --git a/crates/ui-egui/src/proto_panel.rs b/crates/ui-egui/src/proto_panel.rs
index 972f068b..1b2e2df9 100644
--- a/crates/ui-egui/src/proto_panel.rs
+++ b/crates/ui-egui/src/proto_panel.rs
@@ -426,6 +426,8 @@ fn flows_overview(app: &mut FigApp, ui: &mut Ui, doc: &Document, page: NodeId) {
     }
 }
 
+/// Draw prototype settings: device and rotation, device colour, custom size, responsive
+/// toggle and page background, running `proto.settings`.
 fn settings(app: &mut FigApp, ui: &mut Ui, doc: &Document, page: NodeId) {
     if widgets::section_header(ui, tr("Prototype settings"), &[(Icon::Preview, tr("Open prototype preview"))], false).is_some() {
         app.run("proto.preview", json!({}));
@@ -552,6 +554,7 @@ fn custom_size(app: &mut FigApp, ui: &mut Ui, model: Option<proto::Device>) {
     });
 }
 
+/// Show, create or preview the flow starting at `frame` and edit its description.
 fn flow_section(app: &mut FigApp, ui: &mut Ui, doc: &Document, page: NodeId, frame: NodeId) {
     let flows = flows_of(doc, page);
     let mine = flows.iter().find(|f| f.start == frame).cloned();
@@ -579,6 +582,8 @@ fn flow_section(app: &mut FigApp, ui: &mut Ui, doc: &Document, page: NodeId, fra
     }
 }
 
+/// List a node's interactions, add a default click navigation (or Back), open the editor
+/// popover and remove interactions.
 fn interactions(app: &mut FigApp, ui: &mut Ui, doc: &Document, page: NodeId, node: &Node) {
     let t = Tokens::get(ui.ctx());
     let id = node.id;
@@ -696,6 +701,7 @@ fn animates(a: &Action) -> bool {
     )
 }
 
+/// Stable egui id for the prototype key-capture flag.
 fn capture_id() -> Id {
     Id::unique("proto_key_capture")
 }
@@ -704,6 +710,8 @@ fn capturing(ctx: &egui::Context) -> bool {
     ctx.data(|d| d.get_temp::<bool>(capture_id())).unwrap_or(false)
 }
 
+/// Draw an interaction's trigger controls: trigger picker, mouse/delay fields, key capture
+/// and controller-button selection, patching the interaction.
 fn trigger_rows(app: &mut FigApp, ui: &mut Ui, node: NodeId, k: usize, it: &Interaction) {
     let t = Tokens::get(ui.ctx());
     widgets::sublabels(ui, tr("Trigger"), None);
@@ -1021,6 +1029,8 @@ pub(crate) fn action_fields(app: &mut FigApp, ui: &mut Ui, doc: &Document, page:
     }
 }
 
+/// Draw an interaction's animation controls: transition, direction, easing, duration and
+/// custom easing fields, plus an animated curve preview.
 fn animation_rows(app: &mut FigApp, ui: &mut Ui, node: NodeId, k: usize, it: &Interaction) {
     let t = Tokens::get(ui.ctx());
     widgets::sublabels(ui, tr("Animation"), None);
diff --git a/crates/ui-egui/src/proto_reorder_tests.rs b/crates/ui-egui/src/proto_reorder_tests.rs
index 1f70f48d..d69be4f6 100644
--- a/crates/ui-egui/src/proto_reorder_tests.rs
+++ b/crates/ui-egui/src/proto_reorder_tests.rs
@@ -44,6 +44,7 @@ fn setup() -> (Ui, NodeId) {
     (u, btn)
 }
 
+/// Stable id for a prototype node's open action path in the reorder tests.
 fn open_id(btn: NodeId) -> egui::Id {
     egui::Id::unique(("proto_open_action", btn, 0usize))
 }
diff --git a/crates/ui-egui/src/right.rs b/crates/ui-egui/src/right.rs
index e2dca4a6..a084b9d0 100644
--- a/crates/ui-egui/src/right.rs
+++ b/crates/ui-egui/src/right.rs
@@ -78,6 +78,8 @@ impl FigApp {
     }
 }
 
+/// Draw the right panel: people, present and share controls, Design/Prototype tabs and zoom
+/// menu, then route the scroll area to comments, frame presets, design, prototype or inspect.
 pub fn right_panel(app: &mut FigApp, ui: &mut Ui) {
     let t = Tokens::get(ui.ctx());
     let w = ui.available_width();
@@ -393,6 +395,8 @@ fn design(app: &mut FigApp, ui: &mut Ui) {
     crate::export_panel::section(app, ui, &doc, &sel);
 }
 
+/// Draw the page section: background and colour profile, local variables/styles, and the
+/// page export section.
 fn page_section(app: &mut FigApp, ui: &mut Ui, doc: &Document) {
     let t = Tokens::get(ui.ctx());
     let Ok(page) = app.session.page() else { return };
@@ -455,6 +459,8 @@ fn page_section(app: &mut FigApp, ui: &mut Ui, doc: &Document) {
     crate::export_panel::page_section(app, ui, doc, page);
 }
 
+/// Draw the selection header: type name (or Mixed), frame/group conversion, orientation
+/// swap and frame presets, component/mask/boolean quick actions, and instance details.
 fn header(app: &mut FigApp, ui: &mut Ui, doc: &Document, sel: &[NodeId]) {
     let t = Tokens::get(ui.ctx());
     let label = match common(doc, sel, |n| n.kind.label()) {
@@ -589,6 +595,8 @@ fn position(app: &mut FigApp, ui: &mut Ui, doc: &Document, sel: &[NodeId]) {
     ui.add_space(8.0);
 }
 
+/// Draw alignment and distribution, X/Y and rotation with flip/rotate controls, the
+/// absolute-position toggle and frame constraints.
 fn position_fields(app: &mut FigApp, ui: &mut Ui, doc: &Document, sel: &[NodeId]) {
     let ids = sel.to_vec();
     let col = widgets::col_width(ui.available_width());
@@ -807,6 +815,8 @@ fn pretty(s: &str) -> String {
     }
 }
 
+/// Draw visibility/blend/mask, opacity, uniform or per-corner radius, corner smoothing and
+/// the blend-mode row.
 fn appearance(app: &mut FigApp, ui: &mut Ui, doc: &Document, sel: &[NodeId]) {
     let ids = sel.to_vec();
     let visible = common(doc, sel, |n| n.visible).unwrap_or(true);
@@ -1080,6 +1090,8 @@ fn range_fill(app: &mut FigApp, ui: &mut Ui, doc: &Document, id: NodeId, start:
     });
 }
 
+/// Draw a selected-text range fill, or the fill/stroke paint rows with add, style, reorder,
+/// stroke align/weight, per-side weights and advanced stroke settings.
 fn paints(app: &mut FigApp, ui: &mut Ui, doc: &Document, sel: &[NodeId], fills: bool) {
     if fills
         && let Some((id, a, b)) = figcraft_engine::textedit::selected_range(&app.session)
@@ -1641,6 +1653,8 @@ fn paint_label(p: &Paint) -> String {
     }
 }
 
+/// Draw the effect list with add/style/type/toggle/remove/reorder, open settings, and keep an
+/// open picker and settings flags aligned when rows move or are removed.
 fn effects(app: &mut FigApp, ui: &mut Ui, doc: &Document, sel: &[NodeId]) {
     let ids = sel.to_vec();
     let list = common(doc, sel, |n| n.effects.clone());
@@ -1723,6 +1737,8 @@ fn fx_field(app: &mut FigApp, ui: &mut Ui, ids: &[NodeId], i: usize, prop: &str,
     crate::variable_ui::number_field(app, ui, ids, &format!("effects/{i}/{prop}"), Id::unique(("fx", prop, i)), lead, Some(value), "", width)
 }
 
+/// Draw type-specific effect fields for shadows, blurs, noise, texture and glass, using live
+/// scrub edits that stay one undo step and bindable colour fields.
 fn effect_settings(app: &mut FigApp, ui: &mut Ui, ids: &[NodeId], i: usize, e: &Effect) {
     let half = (ui.available_width() - PAD * 2.0 - 8.0) / 2.0;
     let set = |app: &mut FigApp, e2: Effect, scrub: Option<bool>| {
@@ -1959,6 +1975,8 @@ fn fx_color(app: &mut FigApp, ui: &mut Ui, ids: &[NodeId], i: usize, e: &Effect,
     }
 }
 
+/// Draw the layout-grid list with add/style/type/toggle/remove/reorder, per-grid settings,
+/// and keep open-settings flags aligned when rows move or are removed.
 fn grids(app: &mut FigApp, ui: &mut Ui, doc: &Document, sel: &[NodeId]) {
     let ids = sel.to_vec();
     let list = common(doc, sel, |n| n.grids.clone());
diff --git a/crates/ui-egui/src/rtl_names_tests.rs b/crates/ui-egui/src/rtl_names_tests.rs
index c88ab267..22f59817 100644
--- a/crates/ui-egui/src/rtl_names_tests.rs
+++ b/crates/ui-egui/src/rtl_names_tests.rs
@@ -34,6 +34,7 @@ fn caret_x(ctx: &egui::Context, text: &str, cursor: CCursor) -> f32 {
     ctx.fonts_mut(|f| f.layout_no_wrap(text.to_string(), regular(11.0), Color32::WHITE).pos_from_cursor(cursor).min.x)
 }
 
+/// Read the primary character cursor of a test text field.
 fn cursor(ctx: &egui::Context, id: Id) -> CCursor {
     egui::TextEdit::load_state(ctx, id).unwrap().cursor.char_range().unwrap().primary
 }
@@ -75,6 +76,8 @@ fn fonts() -> Option<egui::Context> {
     Some(ctx)
 }
 
+/// Asserts names keep their logical text while glyphs paint in visual order, including
+/// ellipsis placement at the overflow end and mixed-direction rows.
 #[test]
 fn names_keep_logical_text_and_paint_in_visual_order() {
     let Some(ctx) = fonts() else { return };
@@ -137,6 +140,8 @@ fn names_keep_logical_text_and_paint_in_visual_order() {
     });
 }
 
+/// Asserts Arabic letters take joined contextual forms and truncation puts the ellipsis at
+/// the visual end of a right-to-left row.
 #[test]
 fn arabic_joining_and_truncation_use_the_visual_end() {
     let Some(ctx) = fonts() else { return };
@@ -177,6 +182,8 @@ fn arabic_joining_and_truncation_use_the_visual_end() {
     });
 }
 
+/// Asserts the shaper mirrors right-to-left parentheses in both glyph order and the atlas
+/// shapes chosen for them.
 #[test]
 fn rtl_brackets_are_mirrored_by_the_shaper() {
     let Some(ctx) = fonts() else { return };
@@ -211,6 +218,8 @@ fn rtl_brackets_are_mirrored_by_the_shaper() {
     });
 }
 
+/// Asserts Right/Left move the caret visually while logical offsets jump, Shift extends
+/// visually, and typing inserts at the logical caret; Latin text keeps egui's own caret.
 #[test]
 fn rename_caret_moves_visually_with_logical_offsets() {
     let Some(ctx) = fonts() else { return };
@@ -266,6 +275,8 @@ fn rename_caret_moves_visually_with_logical_offsets() {
     assert_eq!(caret(&ctx, lid).0, 2);
 }
 
+/// Asserts clicks map right-to-left visual positions to logical carets, so a click at the
+/// visual left end leaves the caret at the logical end and typing appends there.
 #[test]
 fn clicks_place_the_logical_caret_by_what_is_shown() {
     let Some(ctx) = fonts() else { return };
diff --git a/crates/ui-egui/src/section_panel.rs b/crates/ui-egui/src/section_panel.rs
index 586a5597..f3240d57 100644
--- a/crates/ui-egui/src/section_panel.rs
+++ b/crates/ui-egui/src/section_panel.rs
@@ -48,6 +48,9 @@ pub fn status_dropdown(app: &mut FigApp, ui: &mut Ui, doc: &Document, ids: &[Nod
     });
 }
 
+/// Draw section colour and hide-contents controls, Dev status, changed-reason Resolve, the
+/// last-change note and Resize to fit; returns for an empty selection or one without a Dev
+/// status.
 pub fn section(app: &mut FigApp, ui: &mut Ui, doc: &Document, sel: &[NodeId]) {
     let sections = !sel.is_empty() && sel.iter().all(|i| is_section(doc, *i));
     if sel.is_empty() || !sel.iter().all(|i| has_status(doc, *i)) {
diff --git a/crates/ui-egui/src/select_all_tests.rs b/crates/ui-egui/src/select_all_tests.rs
index a68a6854..d86de12d 100644
--- a/crates/ui-egui/src/select_all_tests.rs
+++ b/crates/ui-egui/src/select_all_tests.rs
@@ -45,6 +45,7 @@ fn selection(ctx: &egui::Context, te: Id) -> Option<(usize, usize)> {
     Some((a.min(b), a.max(b)))
 }
 
+/// Asserts clicking a hex field focuses it and selects all six characters.
 #[test]
 fn a_click_into_a_hex_field_selects_it_all() {
     let ctx = egui::Context::default();
@@ -57,6 +58,7 @@ fn a_click_into_a_hex_field_selects_it_all() {
     assert_eq!(selection(&ctx, id.with("te")), Some((0, 6)));
 }
 
+/// Asserts clicking an inline field selects it all and typing replaces the selection.
 #[test]
 fn a_click_into_an_inline_field_selects_it_all() {
     // A fill's hex in the Design panel, a variable's value, a rename.
@@ -75,6 +77,7 @@ fn a_click_into_an_inline_field_selects_it_all() {
     assert_eq!(out.as_deref(), Some("red"));
 }
 
+/// Asserts clicking a search box selects its whole query.
 #[test]
 fn a_click_into_a_search_box_selects_its_query() {
     let ctx = egui::Context::default();
@@ -87,6 +90,7 @@ fn a_click_into_a_search_box_selects_its_query() {
     assert_eq!(selection(&ctx, id), Some((0, 6)));
 }
 
+/// Asserts Tab focus selects a field's whole value.
 #[test]
 fn tab_into_a_field_selects_it_all() {
     let ctx = egui::Context::default();
@@ -106,6 +110,7 @@ fn tab_into_a_field_selects_it_all() {
     assert_eq!(selection(&ctx, id), Some((0, 7)));
 }
 
+/// Asserts a drag selects a non-empty proper subrange rather than the whole value.
 #[test]
 fn a_drag_selects_only_what_it_covers() {
     let ctx = egui::Context::default();
@@ -120,6 +125,7 @@ fn a_drag_selects_only_what_it_covers() {
     assert!(!(a == 0 && b == q.chars().count()), "not all of it: {a}..{b}");
 }
 
+/// Asserts re-clicking a field after focus was lost mid-edit selects all.
 #[test]
 fn a_field_left_mid_edit_selects_all_on_the_next_click() {
     let ctx = egui::Context::default();
diff --git a/crates/ui-egui/src/selection_colors.rs b/crates/ui-egui/src/selection_colors.rs
index c699788b..682b37fe 100644
--- a/crates/ui-egui/src/selection_colors.rs
+++ b/crates/ui-egui/src/selection_colors.rs
@@ -24,6 +24,9 @@ struct Cache {
     colors: Arc<Vec<SelectionColor>>,
 }
 
+/// Return the cached selection colours when the document and selection match. During an
+/// interaction reuse an existing matching cache, or return an empty list without discovering
+/// colours; otherwise discover and cache them.
 fn colors(ui: &Ui, document: u64, doc: &Arc<Document>, ids: &[NodeId], interacting: bool) -> Arc<Vec<SelectionColor>> {
     let key = Id::unique("selection_colors_cache");
     if let Some(cache) = ui.data(|d| d.get_temp::<Cache>(key))
@@ -49,6 +52,9 @@ pub(crate) fn open_picker(app: &mut FigApp, targets: Vec<PaintTarget>) {
     app.ui.picker = Some(PickerTarget::SelectionColor { targets, selection: ds.selection.clone(), document: ds.uid });
 }
 
+/// Draw the selection-colour groups (at least two): swatch opens the picker, hex and opacity
+/// edits, style/variable detach/apply/bind, and “select layers with this color”; disabled
+/// during an interaction.
 pub fn section(app: &mut FigApp, ui: &mut Ui, doc: &Arc<Document>, ids: &[NodeId]) {
     let Ok(ds) = app.session.ds() else { return };
     let interacting = ds.interaction.is_some();
@@ -249,6 +255,8 @@ mod tests {
         assert!(!p.frame(vec![]).iter().any(|(s, _)| s == "Selection colors"));
     }
 
+    /// Asserts the panel reuses cached colours through a live interaction and refreshes the cache
+    /// after the commit.
     #[test]
     fn panel_keeps_cached_colors_during_interaction_and_refreshes_after_commit() {
         let (mut p, a, _) = Panel::new();
@@ -268,6 +276,8 @@ mod tests {
         assert!(!Arc::ptr_eq(&before.colors, &after.colors));
     }
 
+    /// Asserts no cached colours are discovered during an interaction, and cancelling restores
+    /// the panel with the original colours.
     #[test]
     fn panel_defers_discovery_without_a_matching_cache_during_interaction() {
         let (mut p, a, _) = Panel::new();
diff --git a/crates/ui-egui/src/selection_spacing.rs b/crates/ui-egui/src/selection_spacing.rs
index 7d1d27b4..414348bb 100644
--- a/crates/ui-egui/src/selection_spacing.rs
+++ b/crates/ui-egui/src/selection_spacing.rs
@@ -24,6 +24,8 @@ struct LayoutCache {
     reorder: Option<Arc<ReorderLayout>>,
 }
 
+/// Return one cached spacing/reorder calculation per document, page, selection and frame,
+/// refreshing next frame after an edit and reusing an unchanged document snapshot.
 fn layout(app: &FigApp, ctx: &egui::Context, ids: &[NodeId]) -> Arc<SelectionSpacing> {
     let Ok(ds) = app.session.ds() else { return Arc::new(SelectionSpacing::default()) };
     let key = Id::unique("selection_spacing_layout");
@@ -52,11 +54,13 @@ fn layout(app: &FigApp, ctx: &egui::Context, ids: &[NodeId]) -> Arc<SelectionSpa
     });
     layout
 }
+/// Return the cached reorder layout, first ensuring the shared layout cache is populated.
 fn reorder_layout(app: &FigApp, ctx: &egui::Context, ids: &[NodeId]) -> Option<Arc<ReorderLayout>> {
     layout(app, ctx, ids);
     ctx.data(|d| d.get_temp::<LayoutCache>(Id::unique("selection_spacing_layout"))).and_then(|c| c.reorder)
 }
 
+/// Stable egui id for spacing/reorder drag state.
 fn drag_id() -> Id {
     Id::unique("selection_spacing_drag")
 }
@@ -107,6 +111,8 @@ fn start_drag(app: &mut FigApp, ctx: &egui::Context, ids: Vec<NodeId>, p: Pos2,
     }
 }
 
+/// Draw horizontal and vertical spacing fields, running `arrange.spacing` with
+/// `fromGesture`.
 pub fn panel(app: &mut FigApp, ui: &mut Ui, ids: &[NodeId]) {
     let layout = layout(app, ui.ctx(), ids);
     if layout.horizontal.is_none() && layout.vertical.is_none() {
diff --git a/crates/ui-egui/src/selection_spacing_tests.rs b/crates/ui-egui/src/selection_spacing_tests.rs
index aaeaabc3..b4b384d0 100644
--- a/crates/ui-egui/src/selection_spacing_tests.rs
+++ b/crates/ui-egui/src/selection_spacing_tests.rs
@@ -43,6 +43,7 @@ fn drag(u: &mut Ui, p: Pos2, by: egui::Vec2, release: bool) {
     }
 }
 
+/// Asserts typed and scrubbed spacing changes take effect with exactly one undo step.
 #[test]
 fn spacing_fields_type_scrub_and_keep_one_undo_step() {
     let (mut u, ids) = scene(true);
@@ -88,6 +89,8 @@ fn canvas_gap_drag_keeps_selection_and_undo_redo_for_both_grid_axes() {
     }
 }
 
+/// Asserts Escape rolls a spacing drag back, and releasing outside the window commits once
+/// while keeping the selection.
 #[test]
 fn escape_rolls_back_and_an_outside_release_finishes_the_gesture() {
     let (mut u, ids) = scene(false);
diff --git a/crates/ui-egui/src/shortcuts.rs b/crates/ui-egui/src/shortcuts.rs
index 2abb1cfc..d47d9607 100644
--- a/crates/ui-egui/src/shortcuts.rs
+++ b/crates/ui-egui/src/shortcuts.rs
@@ -205,6 +205,9 @@ pub struct AfterFieldSave {
 }
 
 impl AfterFieldSave {
+    /// Run a deferred field-save binding only if the originating window still exists and owns
+    /// the document; temporarily activate that document, run the binding, then restore the
+    /// previously front tab.
     fn run(self, app: &mut FigApp) {
         // A closed file or one moved to another window cannot turn this into a save of the
         // current tab. The UiState normally stays in its window's pane; validate that too.
@@ -299,6 +302,7 @@ pub(crate) fn revalidate_field_save(app: &FigApp, ctx: &Context, save: Option<Af
     }
 }
 
+/// Stable id, per viewport and editor, for a rejected field-save cancellation.
 fn field_save_cancellation(ctx: &Context, editor: egui::Id) -> egui::Id {
     egui::Id::unique(("field_save_cancelled", ctx.viewport_id(), editor))
 }
@@ -644,12 +648,16 @@ pub(crate) struct ImeInputBaseline {
 }
 
 impl ImeInputBaseline {
+    /// Capture an IME baseline only while a text edit and an active preedit exist, recording
+    /// the IME target and the caret/anchor.
     pub(crate) fn capture(app: &FigApp) -> Option<Self> {
         let te = app.session.ds().ok()?.text_edit.as_ref()?;
         te.preedit.as_ref()?;
         Some(Self { target: ime_target(app)?, caret: te.caret, anchor: te.anchor })
     }
 
+    /// Whether the IME target changed, editing or the preedit ended, or the caret/anchor moved
+    /// since the baseline was captured.
     fn interrupted(&self, app: &FigApp) -> bool {
         ime_target(app) != Some(self.target)
             || app
@@ -661,6 +669,9 @@ impl ImeInputBaseline {
     }
 }
 
+/// Apply a batch of text, IME, paste, copy, cut and key events: reject all IME events for an
+/// interrupted composition, swallow text produced by a key that ran a shortcut, then finish
+/// with triple-click line selection and preedit sync.
 fn text_keys(app: &mut FigApp, ctx: &Context, events: &[Event], ime_input: Option<ImeInputBaseline>) {
     // Validate once before the batch: an accepted DeleteSurrounding deliberately clears preedit,
     // but its following Commit still belongs to the same valid transaction. An interrupted
diff --git a/crates/ui-egui/src/style_picker_tests.rs b/crates/ui-egui/src/style_picker_tests.rs
index f86ddd73..b732c11d 100644
--- a/crates/ui-egui/src/style_picker_tests.rs
+++ b/crates/ui-egui/src/style_picker_tests.rs
@@ -95,6 +95,8 @@ fn text_session() -> (Session, figcraft_doc::NodeId) {
     (s, t)
 }
 
+/// Asserts hovering a text style previews it without an edit, leaving the popover restores
+/// the value, and clicking applies one undo step and closes the picker.
 #[test]
 fn text_styles_preview_on_hover_and_apply_on_click() {
     let (s, t) = text_session();
diff --git a/crates/ui-egui/src/tabs.rs b/crates/ui-egui/src/tabs.rs
index 92ff9f63..6f17910a 100644
--- a/crates/ui-egui/src/tabs.rs
+++ b/crates/ui-egui/src/tabs.rs
@@ -97,6 +97,8 @@ fn tab_drop_position(visible: &[(usize, Rect)], from: usize, pointer_x: f32) ->
     }
 }
 
+/// Draw the top tab bar: Home, document and presenter tabs, new-tab and window controls,
+/// open/close/reorder animation and tab closing, pausing the presenter when going Home.
 pub fn tab_bar(app: &mut FigApp, ui: &mut Ui) {
     let t = Tokens::get(ui.ctx());
     egui::Panel::top("tab_bar").exact_size(HEIGHT).frame(egui::Frame::NONE.fill(t.tab_bar)).show(ui, |ui| {
diff --git a/crates/ui-egui/src/theme.rs b/crates/ui-egui/src/theme.rs
index 80d1399c..9a384294 100644
--- a/crates/ui-egui/src/theme.rs
+++ b/crates/ui-egui/src/theme.rs
@@ -173,6 +173,7 @@ impl Tokens {
     }
 }
 
+/// Stable id for temporary theme tokens.
 fn tokens_id() -> egui::Id {
     egui::Id::unique("figcraft_tokens")
 }
@@ -436,6 +437,7 @@ pub fn c32(c: figcraft_color::Color) -> Color32 {
     Color32::from_rgba_unmultiplied(r, g, b, a)
 }
 
+/// Stable id for the current document-to-screen colour conversion.
 fn screen_conversion_id() -> egui::Id {
     egui::Id::unique("figcraft_screen_conversion")
 }
diff --git a/crates/ui-egui/src/theme_startup_tests.rs b/crates/ui-egui/src/theme_startup_tests.rs
index 1ae40f58..c128a597 100644
--- a/crates/ui-egui/src/theme_startup_tests.rs
+++ b/crates/ui-egui/src/theme_startup_tests.rs
@@ -84,6 +84,8 @@ fn unavailable_system_theme_uses_the_existing_light_fallback() {
     assert_eq!(Tokens::get(&ctx), Tokens::light());
 }
 
+/// Checks that the test graph enables egui's `default_fonts` and `monochrome_emoji_fonts`
+/// features by asserting both a Latin and an emoji glyph are available.
 #[test]
 fn tests_have_the_explicit_default_and_monochrome_emoji_font_features() {
     // 0.37 egui has no default features, and kittest's own dev-features do not propagate to this
diff --git a/crates/ui-egui/src/titlebar_tests.rs b/crates/ui-egui/src/titlebar_tests.rs
index 8fa4ad47..fff303ef 100644
--- a/crates/ui-egui/src/titlebar_tests.rs
+++ b/crates/ui-egui/src/titlebar_tests.rs
@@ -81,6 +81,8 @@ fn window_buttons_minimise_maximise_and_close() {
     assert!(u.frame(vec![]).contains(&ViewportCommand::Close));
 }
 
+/// Asserts closing the custom titlebar over a presenter with unsaved changes asks with the
+/// unsaved-changes dialog instead of emitting `Close`.
 #[test]
 fn titlebar_close_asks_over_the_presenter_when_a_file_is_unsaved() {
     let mut u = Ui::new(TitleBar::Custom);
diff --git a/crates/ui-egui/src/toolbar.rs b/crates/ui-egui/src/toolbar.rs
index 7af3356a..8f8f6cc1 100644
--- a/crates/ui-egui/src/toolbar.rs
+++ b/crates/ui-egui/src/toolbar.rs
@@ -91,6 +91,7 @@ const BOARD_GROUPS: &[Group] = &[
     Group::tools("comment", tr_noop("Comment"), &[(ToolId::Comment, Icon::Comment)]),
 ];
 
+/// Return the last tool index remembered for a toolbar group, falling back to `default`.
 fn remembered(ui: &Ui, key: &str, default: ToolId) -> ToolId {
     ui.data(|d| d.get_temp::<u8>(egui::Id::unique(("tb_last", key)))).and_then(|i| ToolId::ALL.get(i as usize).copied()).unwrap_or(default)
 }
@@ -535,6 +536,8 @@ fn options_flyout(app: &mut FigApp, ui: &mut Ui, g: &Group, bottom_left: egui::P
     }
 }
 
+/// Draw a tool group's flyout above its button, with keyboard/hover highlighting, remembered
+/// selection when a tool is clicked, and Escape to close.
 fn flyout(app: &mut FigApp, ui: &mut Ui, g: &Group, bottom_left: egui::Pos2) {
     let t = Tokens::get(ui.ctx());
     let item_h = 32.0;
diff --git a/crates/ui-egui/src/type_settings_tests.rs b/crates/ui-egui/src/type_settings_tests.rs
index cbde6cc1..421c1ce2 100644
--- a/crates/ui-egui/src/type_settings_tests.rs
+++ b/crates/ui-egui/src/type_settings_tests.rs
@@ -2,6 +2,8 @@
 //! de paragraphe") stays inside the popover, which otherwise widened a little every frame.
 use egui::{Area, Id, Pos2, RawInput, Rect, vec2};
 
+/// Asserts a long type-settings row label does not widen the popover beyond 264 pt across
+/// frames.
 #[test]
 fn a_long_label_does_not_widen_the_type_settings_popover() {
     let ctx = egui::Context::default();
diff --git a/crates/ui-egui/src/typography.rs b/crates/ui-egui/src/typography.rs
index 33c0d5a0..f61aa183 100644
--- a/crates/ui-egui/src/typography.rs
+++ b/crates/ui-egui/src/typography.rs
@@ -1167,10 +1167,13 @@ const ROW: f32 = 26.0;
 /// The font list's tallest (it scrolls past that).
 const LIST_HEIGHT: f32 = 380.0;
 
+/// Return the persisted list of recently used font families.
 fn recent_families(ctx: &egui::Context) -> Vec<String> {
     ctx.data_mut(|d| d.get_persisted::<Vec<String>>(Id::unique(RECENT_KEY))).unwrap_or_default()
 }
 
+/// Remember a font family at the front of the recent list, removing an earlier
+/// case-insensitive match and keeping at most eight entries.
 fn remember_family(ctx: &egui::Context, family: &str) {
     ctx.data_mut(|d| {
         let v = d.get_persisted_mut_or_default::<Vec<String>>(Id::unique(RECENT_KEY));
@@ -1568,6 +1571,8 @@ mod variable_tests {
         assert!(p.app.ui.last_error.is_none(), "{:?}", p.app.ui.last_error);
     }
 
+    /// Asserts bound font family and style chips replace the dropdowns, a selected text range
+    /// offers no variable binding, and detaching restores the last values.
     #[test]
     fn bound_font_family_and_style_show_their_variables_and_detach() {
         let mut p = Panel::new();
diff --git a/crates/ui-egui/src/typography_scrub_tests.rs b/crates/ui-egui/src/typography_scrub_tests.rs
index 1e629acf..9b95b8e5 100644
--- a/crates/ui-egui/src/typography_scrub_tests.rs
+++ b/crates/ui-egui/src/typography_scrub_tests.rs
@@ -44,6 +44,7 @@ impl Fields {
         out.textures_delta.clear();
         out.platform_output.cursor_icon
     }
+    /// Screen position of a typography field's label/lead, used to start a scrub.
     fn lead(&self, key: &str) -> Pos2 {
         let rect = self.ctx.read_response(Id::unique(key).with("click")).unwrap().rect;
         Pos2::new(rect.min.x + 12.0, rect.center().y)
@@ -157,6 +158,8 @@ fn typography_icon_scrub_changes_only_the_selected_characters_without_ending_tex
     assert_eq!(f.value("ty_ls"), 0.0);
 }
 
+/// Asserts typography spacing fields accept typed percent units, commit on Enter, and
+/// Escape restores the previous value without adding an undo step.
 #[test]
 fn typography_spacing_fields_still_accept_typed_units_and_escape_cancels() {
     let mut f = Fields::new();
diff --git a/crates/ui-egui/src/variable_ui.rs b/crates/ui-egui/src/variable_ui.rs
index 776d8aae..fe822a1f 100644
--- a/crates/ui-egui/src/variable_ui.rs
+++ b/crates/ui-egui/src/variable_ui.rs
@@ -40,6 +40,7 @@ struct Picker {
     at: Pos2,
 }
 
+/// Stable egui id for the variable picker.
 fn picker_id() -> Id {
     Id::unique("variable_picker")
 }
diff --git a/crates/ui-egui/src/variables_panel.rs b/crates/ui-egui/src/variables_panel.rs
index 2a9e3c04..372e3f04 100644
--- a/crates/ui-egui/src/variables_panel.rs
+++ b/crates/ui-egui/src/variables_panel.rs
@@ -173,6 +173,8 @@ pub fn show(app: &mut FigApp, ctx: &Context) {
     app.ui.variables = open.then_some(st);
 }
 
+/// Draw the variables header: the title at the left, and the import/export/Close controls at the
+/// right.
 fn header(app: &mut FigApp, ui: &mut Ui, open: &mut bool) {
     let t = Tokens::get(ui.ctx());
     let (r, _) = ui.allocate_exact_size(vec2(ui.available_width(), 44.0), Sense::hover());
@@ -253,6 +255,7 @@ fn extend(app: &mut FigApp, lib: &str, c: &str, st: &mut Editor) {
     }
 }
 
+/// Stable egui id for the rename field of a `Rename` target.
 fn rename_id(target: &Rename) -> Id {
     Id::unique(("var_rename", target))
 }
@@ -281,6 +284,8 @@ fn unique(base: &str, taken: impl Fn(&str) -> bool) -> String {
     (1..10_000).map(|k| if k == 1 { base.to_string() } else { format!("{base} {k}") }).find(|n| !taken(n)).unwrap_or_else(|| base.to_string())
 }
 
+/// Draw the collections sidebar with library headings, collection rows and a create-collection
+/// button.
 fn sidebar(app: &mut FigApp, ui: &mut Ui, views: &[View], local: &Variables, st: &mut Editor) {
     let t = Tokens::get(ui.ctx());
     let (hr, _) = ui.allocate_exact_size(vec2(SIDEBAR_W, 40.0), Sense::hover());
@@ -505,6 +510,8 @@ fn group_of(name: &str) -> &str {
     name.rsplit_once('/').map(|(g, _)| g).unwrap_or("")
 }
 
+/// Draw the variables table for the selected collection: search, library/extended notes,
+/// grouped rows, mode columns and the create-variable row when editable.
 fn table(app: &mut FigApp, ui: &mut Ui, view: &View, st: &mut Editor) {
     let t = Tokens::get(ui.ctx());
     // A sidebar click this frame picked another source: shown next frame.
@@ -594,6 +601,8 @@ fn table(app: &mut FigApp, ui: &mut Ui, view: &View, st: &mut Editor) {
     });
 }
 
+/// Draw a collection's mode header row with rename, duplicate, reorder and delete actions
+/// and an add-mode button when the collection is editable and not extended.
 fn header_row(app: &mut FigApp, ui: &mut Ui, view: &View, coll: &Collection, st: &mut Editor, width: f32) {
     let t = Tokens::get(ui.ctx());
     // An extended collection has the modes of the one it extends.
diff --git a/crates/ui-egui/src/vector_panel.rs b/crates/ui-egui/src/vector_panel.rs
index 29ae8726..07dda3ff 100644
--- a/crates/ui-egui/src/vector_panel.rs
+++ b/crates/ui-egui/src/vector_panel.rs
@@ -72,6 +72,8 @@ fn width_point(app: &mut FigApp, ui: &mut Ui, doc: &Document, ve: &VectorEdit) {
     ui.add_space(8.0);
 }
 
+/// Draw the selected points' position, dimensions, corner radius, mirroring and per-point
+/// stroke cap/join controls; the width tool delegates to its own panel.
 pub fn points(app: &mut FigApp, ui: &mut Ui, doc: &Document, ve: &VectorEdit) {
     if ve.tool == vectoredit::VTool::Width {
         width_point(app, ui, doc, ve);
diff --git a/crates/ui-egui/src/versions.rs b/crates/ui-egui/src/versions.rs
index 3519b610..19eb6a04 100644
--- a/crates/ui-egui/src/versions.rs
+++ b/crates/ui-egui/src/versions.rs
@@ -403,6 +403,8 @@ fn current_row(ui: &mut Ui, more: bool, active: bool) -> bool {
     !active && resp.on_hover_text(tr("Back to the current version")).clicked()
 }
 
+/// Draw one version row with timeline, name, time, up to three description lines and a
+/// more/context menu; returns the chosen preview, restore, edit, duplicate or delete action.
 fn version_row(ui: &mut Ui, row: &Row, last: bool, previewing: bool) -> Option<Action> {
     let t = Tokens::get(ui.ctx());
     let w = ui.available_width();
diff --git a/crates/ui-egui/src/widgets.rs b/crates/ui-egui/src/widgets.rs
index f356b797..a5dd2c7b 100644
--- a/crates/ui-egui/src/widgets.rs
+++ b/crates/ui-egui/src/widgets.rs
@@ -223,6 +223,9 @@ fn cancel_retargeted_field_save(ui: &mut Ui, id: Id) {
     ui.memory_mut(|m| m.surrender_focus(editor));
 }
 
+/// Implement the shared number field: label/icon lead, scrubbing, keyboard stepping and
+/// typing, select-all when a click starts editing, bindable values and deferred-save
+/// cancellation; returns an edit and/or bind event.
 fn number_field_impl(
     ui: &mut Ui,
     id: Id,
diff --git a/crates/ui-egui/src/windows_tests.rs b/crates/ui-egui/src/windows_tests.rs
index 55a7babd..0f5884dd 100644
--- a/crates/ui-egui/src/windows_tests.rs
+++ b/crates/ui-egui/src/windows_tests.rs
@@ -45,6 +45,8 @@ fn names(app: &FigApp) -> Vec<String> {
     app.session.docs.iter().map(|d| d.doc.name.clone()).collect()
 }
 
+/// Asserts closing a window in the presenter shows the unsaved-changes dialog and does not
+/// dismiss the preview.
 #[test]
 fn closing_a_window_in_the_presenter_shows_the_unsaved_changes_dialog() {
     let mut session = Session::new();
@@ -104,6 +106,8 @@ fn windows_hold_tabs_and_close_with_their_files() {
     assert_eq!(app.session.ds().unwrap().doc.name, "A");
 }
 
+/// Asserts a hidden other window answers edits and inspection in its own file while the main
+/// window keeps its file, and a capture parks with a deadline and times out once.
 #[test]
 fn another_hidden_window_answers_requests_that_need_no_frame_in_its_own_file() {
     let mut s = Session::empty();
@@ -180,6 +184,8 @@ fn a_request_for_a_window_on_screen_wakes_it_while_the_main_window_is_hidden() {
     assert!(woken.lock().unwrap().contains(&other), "the other window is asked to draw: {:?}", woken.lock().unwrap());
 }
 
+/// Asserts every direct UI frame clears the logic-tick marker so background work runs each
+/// frame.
 #[test]
 fn every_direct_ui_frame_runs_background_work() {
     // Direct `App::ui` harnesses never call `App::logic`: the tick marker the UI pass consumes
@@ -192,6 +198,8 @@ fn every_direct_ui_frame_runs_background_work() {
     }
 }
 
+/// Asserts synthetic input for a child window reaches the pane that draws it, leaving the
+/// main window's pane untouched.
 #[test]
 fn synthetic_input_for_a_child_window_reaches_the_pane_that_draws_it() {
     let mut s = Session::empty();
@@ -214,6 +222,8 @@ fn synthetic_input_for_a_child_window_reaches_the_pane_that_draws_it() {
     assert_eq!(crate::windows::take_input(&mut app, other), events, "the child's next frame takes its batch");
 }
 
+/// Asserts a child raw-input hook with no batch does not error or drain the root window's
+/// pending acknowledgement.
 #[test]
 fn a_frame_without_a_batch_does_not_error_another_windows_acknowledgement() {
     let mut s = Session::empty();
@@ -238,6 +248,8 @@ fn a_frame_without_a_batch_does_not_error_another_windows_acknowledgement() {
     assert_eq!(app.input_acks[0].reply.id, json!(5));
 }
 
+/// Asserts a child window runs `viewport_setup` and its pane keeps the dark theme after the
+/// swap back.
 #[test]
 fn a_child_window_runs_the_ui_setup_the_main_window_does() {
     // eframe calls `App::ui` only for the root window, so a child that draws while the root does
@@ -263,6 +275,8 @@ fn a_child_window_runs_the_ui_setup_the_main_window_does() {
     assert_eq!(again, Some(json!(true)));
 }
 
+/// Asserts a closed and later reused viewport does not inherit its old IME context
+/// generation.
 #[test]
 fn an_emptied_window_forgets_its_ime_context() {
     // `windows::begin` ends the viewport when a window loses its last file; a later window that