feat: bookmark lines and navigate them with Tab (#208)

CLAUDE.md

@@ -39,7 +39,7 @@ Every subsystem is a `Task<S, M>`: it owns shared state `S` behind an `Arc<RwLoc
 
 - **Interface** (`interfaces/`) — owns the serial port or RTT connection. Enum-dispatched: `InterfaceTask` / `InterfaceCommand` / `InterfaceShared` / `InterfaceType` select between `serial_if.rs` and `rtt_if.rs`.
 - **Inputs** (`inputs/inputs_task.rs`) — the command bar. Parses keystrokes, manages input history (`inputs/history.rs`), and has two `InputMode`s: `Normal` and `Search` (plus a `raw` passthrough flag used only in headless mode).
-- **Graphics** (`graphics/graphics_task.rs`) — renders the TUI, owns the scrollback buffer, handles selection/scrolling, persists the session to a timestamped `.txt` file, and is the sink for log messages. In headless mode it is replaced by `graphics/headless.rs` (same task slot, plain stdout, no TUI).
+- **Graphics** (`graphics/graphics_task.rs`) — renders the TUI, owns the scrollback buffer, handles selection/scrolling, persists the session to a timestamped `.txt` file, and is the sink for log messages. In headless mode it is replaced by `graphics/headless.rs` (same task slot, plain stdout, no TUI). Line-pinned features (bookmarks: right-click to toggle, `Tab`/`Shift+Tab` to jump, yellow timestamp) live in `graphics/screen.rs` and key off the stable per-line `BufferLine::id` so they survive scrollback rotation and filter changes.
 - **PluginEngine** (`plugin/engine.rs`) — runs a Tokio runtime hosting Lua plugins.
 
 ### Data buses (`infra/mpmc.rs`)

README.md

@@ -133,6 +133,10 @@ Press `Ctrl+F` to enter **search mode** and type a query to find it in the captu
 
 ![Search gif](videos/015_search/video.gif)
 
+#### Bookmarks
+
+Jumping to a specific line in a long history is tedious. **Right-click** a line to bookmark it (right-click again to remove the bookmark); a bookmarked line is marked by a **yellow timestamp**. Press `Tab` to jump to the next bookmark and `Shift+Tab` for the previous one, cycling around the ends — the same navigation feel as search. Bookmarks follow their line as the history scrolls and survive changing the filter (a bookmark hidden by a filter reappears once the line is shown again); `Ctrl+L` clears them along with the screen.
+
 #### Message Filter
 
 When received data floods the history — for example a stream of `dbg` lines — use the `!filter` and `!mute` commands to control which received messages are shown. The current filter is shown between square brackets at the top-right of the command bar (e.g. `[.*]`). The two commands share that slot, so setting one replaces the other.
@@ -252,7 +256,8 @@ Anything typed on the command bar that starts with `!` is a command. A line with
 | `Up` / `Down` | Navigate the command history. In search mode: previous / next match. |
 | `Ctrl`+`F` | Toggle search mode. |
 | `Ctrl`+`W` | In search mode: toggle case sensitivity. |
-| `Tab` | Autocomplete a `@tag` from the tag file. |
+| `Tab` | Autocomplete a `@tag` from the tag file (while the pop-up is up); otherwise jump to the next bookmark. |
+| `Shift`+`Tab` | Jump to the previous bookmark. |
 | `Ctrl`+`S` | Save the whole session to a `.txt` file. |
 | `Ctrl`+`R` | Start / stop a record session. |
 | `Ctrl`+`C` | Copy the current selection to the clipboard. |
@@ -266,6 +271,7 @@ Anything typed on the command bar that starts with `!` is a command. A line with
 | `Backspace` / `Delete` | Delete the character before / at the cursor. |
 | Mouse wheel | Scroll the history (hold `Ctrl` to scroll horizontally). |
 | Mouse drag | Select text (copy it with `Ctrl`+`C`). |
+| Mouse right-click | Toggle a bookmark on the clicked line (navigate with `Tab` / `Shift`+`Tab`). |
 
 ## Command-Line Options
 

src/graphics/buffer.rs

@@ -10,6 +10,19 @@ use crate::{
 use chrono::{DateTime, Local};
 use std::ops::AddAssign;
 use std::sync::Arc;
+use std::sync::atomic::{AtomicU64, Ordering};
+
+/// Monotonic source of per-line identifiers. A line keeps its `id` for its whole
+/// lifetime, independent of its position in the buffer, so features that pin to a
+/// specific line (bookmarks) survive re-indexing on capacity drop and the
+/// re-derivation of the displayed view when the filter changes. Every
+/// `BufferLine` is created on the graphics thread, so a `Relaxed` counter is
+/// enough — we only need uniqueness, not cross-thread ordering.
+static NEXT_LINE_ID: AtomicU64 = AtomicU64::new(0);
+
+fn next_line_id() -> u64 {
+    NEXT_LINE_ID.fetch_add(1, Ordering::Relaxed)
+}
 
 /// The payload of a stored buffer line. It is reference-counted so the filtered
 /// view (`Buffer`) can hold cheap clones of the lines in the full history
@@ -126,6 +139,11 @@ where
     T: AsRef<[u8]>,
 {
     pub line: usize,
+    /// Stable identity assigned at creation and preserved across cloning,
+    /// re-indexing and filter changes (see [`next_line_id`]). Unlike `line`
+    /// (the current index, which shifts as lines drop off the top), this never
+    /// changes for a given logical line, so it is what bookmarks pin to.
+    pub id: u64,
     pub timestamp: DateTime<Local>,
     pub level: Option<LogLevel>,
     pub message: T,
@@ -136,6 +154,7 @@ impl BufferLine<LineBytes> {
     pub fn decode(&self, decoder: ScreenDecoder) -> BufferLine<String> {
         BufferLine {
             line: self.line,
+            id: self.id,
             timestamp: self.timestamp,
             level: self.level,
             message: decoder.decode(&self.message),
@@ -146,6 +165,7 @@ impl BufferLine<LineBytes> {
     pub fn new_rx(timestamp: DateTime<Local>, message: Vec<u8>) -> Self {
         Self {
             line: 0,
+            id: next_line_id(),
             timestamp,
             level: None,
             message: message.into(),
@@ -156,6 +176,7 @@ impl BufferLine<LineBytes> {
     pub fn new_tx(timestamp: DateTime<Local>, message: Vec<u8>) -> Self {
         Self {
             line: 0,
+            id: next_line_id(),
             timestamp,
             level: None,
             message: message.into(),
@@ -166,6 +187,7 @@ impl BufferLine<LineBytes> {
     pub fn new_log(timestamp: DateTime<Local>, level: LogLevel, message: Vec<u8>) -> Self {
         Self {
             line: 0,
+            id: next_line_id(),
             timestamp,
             level: Some(level),
             message: message.into(),

src/graphics/graphics_task.rs

@@ -108,6 +108,9 @@ pub enum GraphicsCommand {
     Click(ScreenPosition),
     Move(ScreenPosition),
     CopyToClipboard,
+    ToggleBookmark(ScreenPosition),
+    NextBookmark,
+    PrevBookmark,
 }
 
 pub struct SaveStats {
@@ -583,6 +586,23 @@ impl GraphicsTask {
                     GraphicsCommand::Move(end_pos) => {
                         private.screen.set_selection_end(end_pos);
                     }
+                    GraphicsCommand::ToggleBookmark(pos) => {
+                        private.screen.toggle_bookmark(&private.buffer, pos);
+                    }
+                    GraphicsCommand::NextBookmark => {
+                        let max_main_axis = Self::max_main_axis(&private);
+
+                        private
+                            .screen
+                            .jump_to_next_bookmark(&private.buffer, max_main_axis as usize);
+                    }
+                    GraphicsCommand::PrevBookmark => {
+                        let max_main_axis = Self::max_main_axis(&private);
+
+                        private
+                            .screen
+                            .jump_to_previous_bookmark(&private.buffer, max_main_axis as usize);
+                    }
                     GraphicsCommand::CopyToClipboard => {
                         if let Err(res) =
                             Self::handle_copy_to_clipboard(&mut private, &mut copy_blink)