diff --git a/crates/maestro-daemon/src/worktree_probe.rs b/crates/maestro-daemon/src/worktree_probe.rs
index 440378d..0e732cc 100644
--- a/crates/maestro-daemon/src/worktree_probe.rs
+++ b/crates/maestro-daemon/src/worktree_probe.rs
@@ -45,6 +45,25 @@ pub fn in_the_way(path: &Path) -> Result<InTheWay, ProbeError> {
             breakdown.uncommitted_files += 1;
         }
     }
+    // The line delta behind the sidebar's `+N −M` (docs/SIDEBAR.md). Diffing
+    // the working tree against HEAD covers staged and unstaged changes in one
+    // pass, so a `git add` never makes the counter drop.
+    let numstat = run_git(path, ["diff", "--numstat", "HEAD"]);
+    if let Ok(numstat) = numstat {
+        for line in String::from_utf8_lossy(&numstat.stdout).lines() {
+            let mut cols = line.split('\t');
+            // A binary file reports `-` for both columns; it has no lines to
+            // add to either total.
+            let added: usize = cols.next().and_then(|c| c.parse().ok()).unwrap_or(0);
+            let removed: usize = cols.next().and_then(|c| c.parse().ok()).unwrap_or(0);
+            breakdown.insertions += added;
+            breakdown.deletions += removed;
+        }
+    }
+    // A repo with no commits yet has no HEAD to diff against, and the counts
+    // stay zero rather than failing the whole probe — the file counts above
+    // already reported the work.
+
     // Resolved inside the worktree so a detached HEAD still has a starting
     // point; asking the base repo for `refs/heads/<branch>` fails there.
     let head = run_git(path, ["rev-parse", "--abbrev-ref", "HEAD"])?;
@@ -210,6 +229,67 @@ mod tests {
         assert_eq!(dirty.untracked_files, 1);
     }
 
+    /// docs/SIDEBAR.md: the sidebar renders `+N −M`, so the probe carries the
+    /// line delta of the tracked changes — staged and unstaged together,
+    /// against HEAD.
+    #[test]
+    fn staged_and_unstaged_lines_both_count() {
+        let r = repo_with_worktree();
+        std::fs::write(r.wt().join("staged.txt"), b"a\nb\n").unwrap();
+        git(&r.wt(), &["add", "staged.txt"]);
+        // README loses its one line and gains three, unstaged.
+        std::fs::write(r.wt().join("README"), b"x\ny\nz\n").unwrap();
+
+        let breakdown = in_the_way(&r.wt()).expect("probe");
+        assert_eq!(breakdown.insertions, 5, "2 staged + 3 unstaged");
+        assert_eq!(breakdown.deletions, 1);
+    }
+
+    /// Untracked files are counted as files and never as lines — reading each
+    /// one off disk is the cost the sidebar contract declines to pay.
+    #[test]
+    fn untracked_files_contribute_no_lines() {
+        let r = repo_with_worktree();
+        std::fs::write(r.wt().join("scratch.txt"), b"a\nb\nc\n").unwrap();
+        let breakdown = in_the_way(&r.wt()).expect("probe");
+        assert_eq!(breakdown.untracked_files, 1);
+        assert_eq!(breakdown.insertions, 0);
+        assert_eq!(breakdown.deletions, 0);
+    }
+
+    /// A binary file's numstat is `-\t-`. It must not poison the totals, and
+    /// it must not abort the probe either.
+    #[test]
+    fn binary_changes_add_no_lines() {
+        let r = repo_with_worktree();
+        std::fs::write(r.wt().join("blob.bin"), [0u8, 159, 0, 12]).unwrap();
+        git(&r.wt(), &["add", "blob.bin"]);
+        git(&r.wt(), &["commit", "-qm", "blob"]);
+        std::fs::write(r.wt().join("blob.bin"), [0u8, 1, 2, 3, 4]).unwrap();
+
+        let breakdown = in_the_way(&r.wt()).expect("probe");
+        assert_eq!(breakdown.uncommitted_files, 1);
+        assert_eq!(breakdown.insertions, 0);
+        assert_eq!(breakdown.deletions, 0);
+    }
+
+    /// A line delta alone never decides `is_clear` — the file counts do — so a
+    /// mode change with no line delta still blocks a kill.
+    #[test]
+    fn a_line_less_change_still_blocks() {
+        let r = repo_with_worktree();
+        let script = r.wt().join("run.sh");
+        std::fs::write(&script, b"echo hi\n").unwrap();
+        git(&r.wt(), &["add", "run.sh"]);
+        git(&r.wt(), &["commit", "-qm", "script"]);
+        git(&r.wt(), &["update-index", "--chmod=+x", "run.sh"]);
+
+        let breakdown = in_the_way(&r.wt()).expect("probe");
+        assert_eq!(breakdown.insertions, 0);
+        assert_eq!(breakdown.deletions, 0);
+        assert!(!breakdown.is_clear());
+    }
+
     #[test]
     fn ignored_files_never_count() {
         let r = repo_with_worktree();
diff --git a/crates/maestro-protocol/src/lib.rs b/crates/maestro-protocol/src/lib.rs
index 2dfbed6..2e6cdfa 100644
--- a/crates/maestro-protocol/src/lib.rs
+++ b/crates/maestro-protocol/src/lib.rs
@@ -236,12 +236,71 @@ pub struct InTheWay {
     /// Commits on the branch reachable from no remote-tracking ref.
     #[serde(default)]
     pub unpushed_commits: usize,
+    /// Lines added across the tracked changes — staged and unstaged alike,
+    /// measured against `HEAD`. Untracked files contribute nothing: counting
+    /// their lines means reading every one off disk, and they already have
+    /// their own count above (docs/SIDEBAR.md).
+    #[serde(default)]
+    pub insertions: usize,
+    /// Lines removed across the same tracked changes.
+    #[serde(default)]
+    pub deletions: usize,
 }
 
 impl InTheWay {
     /// Nothing blocks any more — the work has since been committed and pushed.
+    ///
+    /// The line counts are not consulted: they describe the same tracked
+    /// changes `uncommitted_files` counts, and a change with no line delta —
+    /// a mode change, a rename — still blocks.
     pub fn is_clear(&self) -> bool {
-        *self == Self::default()
+        self.uncommitted_files == 0 && self.untracked_files == 0 && self.unpushed_commits == 0
+    }
+}
+
+/// Which fragment of the compact blocked-work stat a value is, and so which
+/// colour the client paints it (docs/SIDEBAR.md).
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum StatKind {
+    /// Lines added.
+    Added,
+    /// Lines removed.
+    Removed,
+    /// Changed tracked files, when the change carries no line delta.
+    Files,
+    /// Untracked files.
+    Untracked,
+    /// Unpushed commits.
+    Unpushed,
+}
+
+impl InTheWay {
+    /// The breakdown as diff notation: `+124`, `-18`, `?3`, `↑2`.
+    ///
+    /// The line counts cover tracked changes only, so a tree whose only
+    /// tracked change carries no line delta — a mode change, a rename —
+    /// reports the file count (`~2`) rather than claiming `+0 -0`. Both
+    /// sidebars render exactly these fragments; [`Display`](std::fmt::Display)
+    /// remains the spelled-out phrasing for the kill refusal and the tooltip.
+    pub fn stats(&self) -> Vec<(StatKind, String)> {
+        let mut out = Vec::new();
+        if self.insertions > 0 || self.deletions > 0 {
+            if self.insertions > 0 {
+                out.push((StatKind::Added, format!("+{}", self.insertions)));
+            }
+            if self.deletions > 0 {
+                out.push((StatKind::Removed, format!("-{}", self.deletions)));
+            }
+        } else if self.uncommitted_files > 0 {
+            out.push((StatKind::Files, format!("~{}", self.uncommitted_files)));
+        }
+        if self.untracked_files > 0 {
+            out.push((StatKind::Untracked, format!("?{}", self.untracked_files)));
+        }
+        if self.unpushed_commits > 0 {
+            out.push((StatKind::Unpushed, format!("↑{}", self.unpushed_commits)));
+        }
+        out
     }
 }
 
@@ -544,6 +603,50 @@ mod tests {
         assert!(is_compatible("unknown"));
     }
 
+    /// docs/SIDEBAR.md: the sidebars render the breakdown as diff notation.
+    #[test]
+    fn stats_read_as_a_diff() {
+        let w = InTheWay {
+            uncommitted_files: 3,
+            untracked_files: 2,
+            unpushed_commits: 1,
+            insertions: 124,
+            deletions: 18,
+        };
+        let text: Vec<String> = w.stats().into_iter().map(|(_, t)| t).collect();
+        assert_eq!(text, ["+124", "-18", "?2", "↑1"]);
+        let kinds: Vec<StatKind> = w.stats().into_iter().map(|(k, _)| k).collect();
+        assert_eq!(
+            kinds,
+            [
+                StatKind::Added,
+                StatKind::Removed,
+                StatKind::Untracked,
+                StatKind::Unpushed
+            ]
+        );
+    }
+
+    /// A change with no line delta — a mode change — still has to say
+    /// something, and `+0 -0` would be a lie about the tree.
+    #[test]
+    fn stats_fall_back_to_the_file_count_without_a_line_delta() {
+        let w = InTheWay {
+            uncommitted_files: 2,
+            ..InTheWay::default()
+        };
+        let text: Vec<String> = w.stats().into_iter().map(|(_, t)| t).collect();
+        assert_eq!(text, ["~2"]);
+        assert!(!w.is_clear());
+    }
+
+    /// A clear tree says nothing at all — the fragment is omitted, not empty.
+    #[test]
+    fn a_clear_tree_has_no_stats() {
+        assert!(InTheWay::default().stats().is_empty());
+        assert!(InTheWay::default().is_clear());
+    }
+
     fn round_trip<T>(value: &T) -> T
     where
         T: Serialize + for<'de> Deserialize<'de>,
diff --git a/crates/maestro-tui/src/sidebar.rs b/crates/maestro-tui/src/sidebar.rs
index 5b37b09..5e79422 100644
--- a/crates/maestro-tui/src/sidebar.rs
+++ b/crates/maestro-tui/src/sidebar.rs
@@ -9,7 +9,7 @@ use std::path::PathBuf;
 
 use chrono::Utc;
 use maestro_protocol::display::{abbreviate_dir, abbreviate_folder_name, session_tree_path};
-use maestro_protocol::{ActivityState, Session, SessionStatus};
+use maestro_protocol::{ActivityState, Session, SessionStatus, StatKind};
 use ratatui::layout::Rect;
 use ratatui::style::{Color, Modifier, Style};
 use ratatui::text::{Line, Span};
@@ -283,7 +283,16 @@ impl Sidebar {
         }
         let mut tail: Vec<Span<'static>> = Vec::new();
         if let Some(b) = blocked {
-            tail.push(Span::styled(format!(" ⚠ {b}"), muted));
+            let palette = palette::active();
+            let surface = palette.surface(highlighted && focused);
+            for (kind, text) in b.stats() {
+                let style = match kind {
+                    StatKind::Added => muted.fg(surface.active),
+                    StatKind::Removed => muted.fg(surface.error),
+                    _ => muted,
+                };
+                tail.push(Span::styled(format!(" {text}"), style));
+            }
         }
         if dead {
             tail.push(Span::styled(" exited", muted));
@@ -627,14 +636,18 @@ mod tests {
     }
 
     /// #83 via docs/SIDEBAR.md: blocked work lives on the meta line now, not
-    /// on the name row; a clear or unprobed worktree never warns.
+    /// on the name row, and reads as diff notation; a clear or unprobed
+    /// worktree says nothing.
     #[test]
-    fn blocked_session_warns_on_its_meta_line() {
+    fn blocked_session_states_its_diff_on_the_meta_line() {
         let mut blocked = session_named(1, "claude");
         blocked.activity_since = Utc::now() - Duration::seconds(5);
         blocked.blocked_work = Some(InTheWay {
+            uncommitted_files: 2,
+            untracked_files: 3,
             unpushed_commits: 4,
-            ..InTheWay::default()
+            insertions: 124,
+            deletions: 18,
         });
         let mut clear = session_named(2, "bash");
         clear.blocked_work = Some(InTheWay::default());
@@ -644,31 +657,66 @@ mod tests {
             highlight: None,
             attached: Default::default(),
         };
-        let all = rows(&draw(&sb, 40, 10));
+        let all = rows(&draw(&sb, 44, 10));
 
         let meta = all
             .iter()
-            .find(|l| l.contains("⚠"))
-            .expect("blocked card must warn somewhere");
-        assert!(
-            meta.contains("4 unpushed commits"),
-            "warning must carry InTheWay's summary: {meta:?}"
-        );
+            .find(|l| l.contains("+124"))
+            .expect("blocked card must state its diff somewhere");
+        for fragment in ["-18", "?3", "↑4"] {
+            assert!(
+                meta.contains(fragment),
+                "meta line must carry {fragment}: {meta:?}"
+            );
+        }
         let name_row = row_containing(&all, "claude");
         assert!(
-            !name_row.contains('⚠'),
-            "warning moved off the name row: {name_row:?}"
+            !name_row.contains("+124"),
+            "the diff stays off the name row: {name_row:?}"
         );
         for name in ["bash", "vim"] {
             let idx = all.iter().position(|l| l.contains(name)).unwrap();
             assert!(
-                !all[idx + 1].contains('⚠'),
-                "{name} must not warn: {:?}",
+                !all[idx + 1].contains('+') && !all[idx + 1].contains('?'),
+                "{name} must not state a diff: {:?}",
                 all[idx + 1]
             );
         }
     }
 
+    /// The additions and deletions are the only coloured fragments: they are
+    /// what a reader scans for, and colouring the rest would make the line
+    /// compete with the activity dot.
+    #[test]
+    fn the_diff_colours_only_its_additions_and_deletions() {
+        let mut s = session_named(1, "claude");
+        s.blocked_work = Some(InTheWay {
+            uncommitted_files: 1,
+            untracked_files: 0,
+            unpushed_commits: 2,
+            insertions: 7,
+            deletions: 3,
+        });
+        let sb = Sidebar {
+            sessions: vec![s],
+            highlight: None,
+            attached: Default::default(),
+        };
+        let buf = draw(&sb, 44, 8);
+        let palette = palette::active();
+        let surface = palette.surface(false);
+        let colour_of = |needle: char| {
+            (0..buf.area.width)
+                .flat_map(|x| (0..buf.area.height).map(move |y| (x, y)))
+                .find(|&(x, y)| buf[(x, y)].symbol() == needle.to_string())
+                .map(|(x, y)| buf[(x, y)].fg)
+                .expect("fragment must be drawn")
+        };
+        assert_eq!(colour_of('+'), surface.active);
+        assert_eq!(colour_of('-'), surface.error);
+        assert_eq!(colour_of('↑'), surface.muted);
+    }
+
     /// A fresh session still gets its unconditional second line, but no
     /// duration until it has been held in state for 30 seconds.
     #[test]
@@ -929,7 +977,7 @@ mod tests {
         let meta = content(&all[idx + 1]);
         assert!(meta.contains('…'), "truncated detail ends with …: {meta:?}");
         assert!(
-            meta.contains("2 unpushed commits"),
+            meta.contains("↑2"),
             "blocked work stays on the line: {meta:?}"
         );
         assert!(
@@ -1062,7 +1110,7 @@ mod tests {
             attached: Default::default(),
         };
         let all = rows(&draw(&sb, 29, 6));
-        assert!(all[3].contains("⚠ 1 uncommitted file"), "{:?}", all[3]);
+        assert!(all[3].contains("~1"), "{:?}", all[3]);
         let meta = content(&all[3]);
         assert!(meta.ends_with('…'), "command must truncate: {meta:?}");
     }
@@ -1081,7 +1129,7 @@ mod tests {
             attached: Default::default(),
         };
         let all = rows(&draw(&sb, 40, 6));
-        assert!(all[3].contains("⚠ 1 uncommitted file"), "{:?}", all[3]);
+        assert!(all[3].contains("~1"), "{:?}", all[3]);
         assert!(
             all[3].contains("bash"),
             "command must survive: {:?}",
diff --git a/docs/SIDEBAR.md b/docs/SIDEBAR.md
index 9b378c8..af08c4a 100644
--- a/docs/SIDEBAR.md
+++ b/docs/SIDEBAR.md
@@ -37,7 +37,7 @@ itself is not.
 Line 2 reads left to right:
 
 ```
-<dot> [<duration>] [<detail>] [<blocked work> | exited] <command>
+<dot> [<duration>] [<detail>] [<diff stat> | exited] <command>
 ```
 
 Its minimum content is therefore the dot and the command.
@@ -64,12 +64,46 @@ truncates with `…` ahead of the trailing fragments — a long detail never
 pushes `<blocked work>`, `exited`, or `<command>` off the line, and neither
 client ever lets it wrap.
 
+`<diff stat>` is the blocked-work breakdown (#83) in diff notation, replacing
+the spelled-out `⚠ 3 uncommitted files, 2 unpushed commits`. It renders only
+while something would block an unforced kill, and reads:
+
+```
++<insertions> -<deletions> ?<untracked files> ↑<unpushed commits>
+```
+
+Each fragment is omitted when its count is zero. The line counts cover
+**tracked** changes only — staged and unstaged together, measured against
+`HEAD` — so a `git add` never makes the counter drop. Untracked files are
+counted as files, not lines: counting their lines means reading every one off
+disk, and `?3` already says what is there. A tree whose only tracked change
+carries no line delta — a mode change, a rename — shows `~<changed files>`
+instead of the additions and deletions, since `+0 -0` would describe it
+wrongly.
+
+Only `+` and `-` take colour (`--live` / `--danger` in the web client, the
+surface's `active` / `error` roles in the TUI); `~`, `?` and `↑` stay muted, so
+the fragment reads as a diff rather than as an alarm. The spelled-out phrasing
+of `maestro_protocol::InTheWay`'s `Display` does not disappear: it is the web
+card's tooltip and the wording of the kill refusal, so no two clients describe
+the same tree differently.
+
 `<command>` is unconditional and muted: the session's command line, shown on
 every card in both clients — no omission in the TUI, no name-vs-command
 comparison gating it. A session named by its command line then shows the same
 string on both lines; that is accepted, the price of a row that never changes
 height.
 
+In the **web client** the command's leading program is replaced by that tool's
+icon when it is one we have a mark for — Claude Code, Codex, opencode, Gemini
+CLI, Aider, Cursor, pi, and any shell — and only the remaining words of the
+command line follow as text. Recognition looks through a path, leading
+`FOO=bar` assignments and wrappers (`sudo`, `env`, `npx`, `pnpm dlx`, …); an
+unrecognised program keeps its full text, so the card never shows a mark
+standing for the wrong tool. The full command line stays in the card's tooltip
+either way. The **TUI** keeps the command as text: a terminal cannot be assumed
+to have a font carrying tool glyphs.
+
 ## Colour per activity state
 
 The state word is never spelled out — the colour carries it.
@@ -95,9 +129,10 @@ surface; a colour chosen for the card background is never painted onto the
 selection background. Contrast is a property of the palette (values are RGB)
 and is asserted in the palette's tests, not left to the terminal theme.
 
-The duration text inherits its state's colour; the blocked-work, exited and
-command fragments use the surface's `muted` role, since the ⚠ glyph already
-signals severity.
+The duration text inherits its state's colour; the exited and command
+fragments use the surface's `muted` role, as do the diff stat's `~`, `?` and
+`↑` fragments. Only `+` and `-` step outside the surface's muted role, and they
+take the `active` and `error` roles of the same surface.
 
 ## Duration format
 
diff --git a/web/src/catalog.test.ts b/web/src/catalog.test.ts
index 8990206..00afeeb 100644
--- a/web/src/catalog.test.ts
+++ b/web/src/catalog.test.ts
@@ -47,15 +47,33 @@ function rowFor(el: HTMLElement, id: string): HTMLElement | null {
 }
 
 describe("blocked-work indicator (#83)", () => {
-  it("marks the row of a blocked session with the shared phrasing", () => {
+  it("marks the row of a blocked session in diff notation", () => {
     const blocked = session({
       id: "aaaaaaaa-0000-0000-0000-000000000001",
-      blocked_work: { uncommitted_files: 3, unpushed_commits: 2 },
+      blocked_work: {
+        uncommitted_files: 3,
+        unpushed_commits: 2,
+        insertions: 124,
+        deletions: 18,
+      },
     });
     const el = renderSidebar(storeWith([blocked])).el;
     const badge = rowFor(el, blocked.id)?.querySelector(".leaf-blocked");
-    expect(badge?.textContent).toContain("⚠");
-    expect(badge?.textContent).toContain("3 uncommitted files, 2 unpushed commits");
+    expect(badge?.textContent).toBe("+124-18↑2");
+    // The spelled-out breakdown survives in the tooltip.
+    expect(badge?.getAttribute("title")).toContain(
+      "3 uncommitted files, 2 unpushed commits",
+    );
+  });
+
+  it("falls back to the file count when tracked changes carry no lines", () => {
+    const blocked = session({
+      id: "aaaaaaaa-0000-0000-0000-00000000001a",
+      blocked_work: { uncommitted_files: 2, untracked_files: 1 },
+    });
+    const el = renderSidebar(storeWith([blocked])).el;
+    const badge = rowFor(el, blocked.id)?.querySelector(".leaf-blocked");
+    expect(badge?.textContent).toBe("~2?1");
   });
 
   it("does not mark clear or unprobed sessions", () => {
@@ -161,7 +179,7 @@ describe("session cards (#107)", () => {
     expect(line2).not.toBeNull();
     expect(line2?.querySelector(".activity-dot")).not.toBeNull();
     expect(line2?.querySelector(".activity-duration")).toBeNull();
-    expect(line2?.querySelector(".leaf-cmd")?.textContent).toBe("claude");
+    expect(line2?.querySelector(".leaf-cmd")).not.toBeNull();
   });
 
   it("shows dot + floored duration once the state has been held past 30s", () => {
@@ -177,14 +195,40 @@ describe("session cards (#107)", () => {
     expect(line2?.querySelector(".activity-duration")?.textContent).toBe("4m");
   });
 
-  it("renders the command when the session name equals it", () => {
+  it("renders the command as its tool icon when the tool is known", () => {
     const s = session({
       id: "aaaaaaaa-0000-0000-0000-00000000001b",
       command: "claude",
       metadata: { name: "claude" },
     });
     const el = renderSidebar(storeWith([s])).el;
-    expect(rowFor(el, s.id)?.querySelector(".card-line2 .leaf-cmd")?.textContent).toBe("claude");
+    const cmd = rowFor(el, s.id)?.querySelector<HTMLElement>(".card-line2 .leaf-cmd");
+    expect(cmd?.querySelector(".tool-icon")?.getAttribute("data-tool")).toBe("claude");
+    expect(cmd?.getAttribute("title")).toBe("claude");
+    // The icon said it all: no text left over.
+    expect(cmd?.querySelector(".leaf-cmd-rest")).toBeNull();
+  });
+
+  it("keeps the command's arguments as text beside the icon", () => {
+    const s = session({
+      id: "aaaaaaaa-0000-0000-0000-00000000001c",
+      command: "claude --resume",
+    });
+    const el = renderSidebar(storeWith([s])).el;
+    const cmd = rowFor(el, s.id)?.querySelector<HTMLElement>(".card-line2 .leaf-cmd");
+    expect(cmd?.querySelector(".tool-icon")?.getAttribute("data-tool")).toBe("claude");
+    expect(cmd?.querySelector(".leaf-cmd-rest")?.textContent).toBe("--resume");
+  });
+
+  it("keeps an unknown command as plain text", () => {
+    const s = session({
+      id: "aaaaaaaa-0000-0000-0000-00000000001d",
+      command: "hx src/main.rs",
+    });
+    const el = renderSidebar(storeWith([s])).el;
+    const cmd = rowFor(el, s.id)?.querySelector<HTMLElement>(".card-line2 .leaf-cmd");
+    expect(cmd?.querySelector(".tool-icon")).toBeNull();
+    expect(cmd?.querySelector(".leaf-cmd-rest")?.textContent).toBe("hx src/main.rs");
   });
 
   it("maps each activity state to its contract slug", () => {
@@ -222,15 +266,20 @@ describe("session cards (#107)", () => {
     expect(line2?.querySelector(".activity-duration")?.textContent).toBe("2m");
   });
 
-  it("moves blocked work onto line 2 in the shared phrasing", () => {
+  it("moves blocked work onto line 2 as diff notation", () => {
     const s = session({
       id: "aaaaaaaa-0000-0000-0000-000000000017",
-      blocked_work: { uncommitted_files: 3, unpushed_commits: 2 },
+      blocked_work: {
+        uncommitted_files: 3,
+        unpushed_commits: 2,
+        insertions: 124,
+        deletions: 18,
+      },
     });
     const el = renderSidebar(storeWith([s])).el;
     const line2 = rowFor(el, s.id)?.querySelector<HTMLElement>(".card-line2");
-    expect(line2?.textContent).toContain("⚠");
-    expect(line2?.textContent).toContain("3 uncommitted files, 2 unpushed commits");
+    expect(line2?.textContent).toContain("+124");
+    expect(line2?.textContent).toContain("-18");
     // Line 1 carries no badges.
     expect(rowFor(el, s.id)?.querySelector(".leaf-badge")).toBeNull();
   });
diff --git a/web/src/catalog.ts b/web/src/catalog.ts
index 6a73478..6c88d24 100644
--- a/web/src/catalog.ts
+++ b/web/src/catalog.ts
@@ -3,9 +3,10 @@ import { getDaemonInfo, killSession, renameSession } from "./api.js";
 import { openContextMenu } from "./contextMenu.js";
 import { isTypingTarget, toggleHelp } from "./help.js";
 import { CatalogStore } from "./events.js";
-import type { Session } from "./types.js";
+import type { InTheWay, Session } from "./types.js";
 import {
   abbreviateFolderName,
+  blockerStats,
   customSessionName,
   formatInTheWay,
   MAX_SESSION_NAME_LEN,
@@ -13,6 +14,7 @@ import {
   sessionBlockers,
   sessionName,
 } from "./types.js";
+import { splitCommand, toolIconSvg } from "./toolIcon.js";
 import {
   activityColorSlug,
   activityDurationLabel,
@@ -73,15 +75,33 @@ function metaLine(s: Session, now: number): string {
     s.activity_detail
       ? `<span class="activity-detail">${escapeHtml(s.activity_detail)}</span>`
       : "",
-    blockers
-      ? `<span class="card-flag leaf-blocked" title="Kill will be refused unless forced">⚠ ${escapeHtml(formatInTheWay(blockers))}</span>`
-      : "",
+    blockers ? blockedFragment(blockers) : "",
     dead ? `<span class="card-flag">exited</span>` : "",
-    `<span class="card-flag leaf-cmd" title="${escapeHtml(s.command)}">${escapeHtml(s.command)}</span>`,
+    commandFragment(s.command),
   ];
   return `<span class="card-line2" data-activity="${slug}">${fragments.join("")}</span>`;
 }
 
+/** docs/SIDEBAR.md: blocked work renders as diff notation — `+124 -18 ?3 ↑2`
+ * — with the spelled-out breakdown kept in the tooltip. */
+function blockedFragment(blockers: InTheWay): string {
+  const stats = blockerStats(blockers)
+    .map((st) => `<span class="blocked-stat" data-stat="${st.kind}">${escapeHtml(st.text)}</span>`)
+    .join("");
+  const title = `Kill will be refused unless forced — ${formatInTheWay(blockers)}`;
+  return `<span class="card-flag leaf-blocked" title="${escapeHtml(title)}">${stats}</span>`;
+}
+
+/** docs/SIDEBAR.md: the command's leading program becomes its tool icon when
+ * we have a mark for it, and only the remaining words stay as text. The full
+ * command line stays in the tooltip either way. */
+function commandFragment(command: string): string {
+  const { tool, rest } = splitCommand(command);
+  const icon = tool ? toolIconSvg(tool) : null;
+  const text = icon ? rest : command;
+  return `<span class="card-flag leaf-cmd" title="${escapeHtml(command)}">${icon ?? ""}${text ? `<span class="leaf-cmd-rest">${escapeHtml(text)}</span>` : ""}</span>`;
+}
+
 function renderNode(node: TreeNode, depth: number): HTMLElement {
   if (node.kind === "folder") {
     const wrap = document.createElement("div");
@@ -341,12 +361,10 @@ export function renderTopbar(store: CatalogStore, onToggleSidebar?: () => void):
 }
 
 /** Two-tier sidebar highlight state (issue #33): which sessions are open in some
- *  pane (quiet), which one is focused (loud), and a stable per-session colour so
- *  a row maps to its pane. */
+ *  pane (quiet), and which one is focused (loud). */
 export interface SidebarHighlights {
   open: Set<string>;
   focused: string | null;
-  colors: Map<string, string>;
 }
 
 /** Live handle to the persistent sidebar (built once, survives navigation). */
@@ -356,7 +374,7 @@ export interface SidebarHandle {
   /** Highlight the row for `id` (or clear it with `null`) as the focused session.
    *  Back-compat shim over {@link setHighlights}. */
   setActive(id: string | null): void;
-  /** Apply the full open/focused/colour highlight state. */
+  /** Apply the full open/focused highlight state. */
   setHighlights(h: SidebarHighlights): void;
   /** Hand the keyboard to the session list, highlighting a row to walk from. */
   focusList(): void;
@@ -469,7 +487,7 @@ export function renderSidebar(store: CatalogStore, opts: SidebarOptions = {}): S
     refresh();
   });
 
-  let highlights: SidebarHighlights = { open: new Set(), focused: null, colors: new Map() };
+  let highlights: SidebarHighlights = { open: new Set(), focused: null };
   const applyHighlights = () => {
     for (const n of treeHost.querySelectorAll<HTMLElement>(".tree-leaf")) {
       const id = n.dataset.sessionId;
@@ -478,9 +496,6 @@ export function renderSidebar(store: CatalogStore, opts: SidebarOptions = {}): S
       const open = highlights.open.has(id);
       n.classList.toggle("is-active", focused);
       n.classList.toggle("is-open", open && !focused);
-      const color = highlights.colors.get(id);
-      if (color && (open || focused)) n.style.setProperty("--mv-color", color);
-      else n.style.removeProperty("--mv-color");
     }
   };
 
@@ -605,7 +620,6 @@ export function renderSidebar(store: CatalogStore, opts: SidebarOptions = {}): S
       highlights = {
         open: id ? new Set([id]) : new Set(),
         focused: id,
-        colors: new Map(),
       };
       applyHighlights();
     },
diff --git a/web/src/mock.ts b/web/src/mock.ts
index dc9fc6f..597f958 100644
--- a/web/src/mock.ts
+++ b/web/src/mock.ts
@@ -14,6 +14,7 @@ function sess(
   status: "Running" | "Dead",
   cwd: string,
   name?: string,
+  blocked_work?: Session["blocked_work"],
 ): Session {
   const seed = parseInt(id.slice(-1), 16) || 0;
   return {
@@ -30,6 +31,7 @@ function sess(
     last_activity_at: new Date(Date.now() - seed * 11_000).toISOString(),
     // The session tree nests by current_cwd; default it to the spawn dir.
     current_cwd: cwd,
+    blocked_work,
   };
 }
 
@@ -109,16 +111,26 @@ function stubSpawnApi(): void {
 export function seedMock(store: CatalogStore): void {
   const sessions: Session[] = [
     // ~/git/maestro/web/* — deep dir chain; "~/git/maestro" collapses to one node.
-    sess("a1b2c3d4-0000-0000-0000-000000000001", "claude", "Running", "/home/dev/git/maestro/web", "redesign"),
+    sess("a1b2c3d4-0000-0000-0000-000000000001", "claude", "Running", "/home/dev/git/maestro/web", "redesign", {
+      uncommitted_files: 4,
+      untracked_files: 2,
+      unpushed_commits: 1,
+      insertions: 312,
+      deletions: 47,
+    }),
     sess("a1b2c3d4-0000-0000-0000-000000000002", "vite dev", "Running", "/home/dev/git/maestro/web", "dev-server"),
     sess("a1b2c3d4-0000-0000-0000-000000000003", "bash", "Dead", "/home/dev/git/maestro/web", "scratch"),
-    sess("a1b2c3d4-0000-0000-0000-000000000004", "claude", "Running", "/home/dev/git/maestro/web/tests", "e2e-fixes"),
+    sess("a1b2c3d4-0000-0000-0000-000000000004", "codex --resume", "Running", "/home/dev/git/maestro/web/tests", "e2e-fixes", {
+      uncommitted_files: 1,
+    }),
     // ~/git/maestro/crates/* — sibling subtree under the same repo.
     sess("a1b2c3d4-0000-0000-0000-000000000005", "claude", "Running", "/home/dev/git/maestro/crates/daemon", "daemon-work"),
     sess("a1b2c3d4-0000-0000-0000-000000000006", "cargo watch -x test", "Running", "/home/dev/git/maestro/crates/daemon", "test-loop"),
     sess("a1b2c3d4-0000-0000-0000-000000000007", "cargo run -- daemon", "Running", "/home/dev/git/maestro/crates/daemon", "daemon"),
     // ~/work/acme/* — a separate top-level dir on the same host.
-    sess("a1b2c3d4-0000-0000-0000-000000000008", "claude", "Running", "/home/dev/work/acme/api", "billing-api"),
+    sess("a1b2c3d4-0000-0000-0000-000000000008", "gemini", "Running", "/home/dev/work/acme/api", "billing-api", {
+      untracked_files: 3,
+    }),
     sess("a1b2c3d4-0000-0000-0000-000000000009", "pnpm dev", "Dead", "/home/dev/work/acme/web", "dashboard"),
     // ~/git/dotfiles — single session, fully collapsed chain.
     sess("a1b2c3d4-0000-0000-0000-000000000010", "opencode", "Running", "/home/dev/git/dotfiles", "dotfiles"),
diff --git a/web/src/multiview.ts b/web/src/multiview.ts
index f19de89..3da26a8 100644
--- a/web/src/multiview.ts
+++ b/web/src/multiview.ts
@@ -22,7 +22,6 @@ import {
   removeLeaf,
   splitLeaf,
 } from "./layout.js";
-import { sessionColor } from "./sessioncolor.js";
 import type { AttachInfo } from "./attach.js";
 import { createSpawnForm, type SpawnFormHandle } from "./spawnForm.js";
 
@@ -97,12 +96,6 @@ export function createMultiView(opts: MultiViewOptions): MultiView {
 
   // ---- highlight helpers ----
 
-  function colorMap(): Map<string, string> {
-    const m = new Map<string, string>();
-    for (const id of openSessions(layout)) m.set(id, sessionColor(id));
-    return m;
-  }
-
   function focusedLeafSession(): string | null {
     const tab = activeTab(layout);
     const fl = tab.focusedLeafId ? findLeaf(tab.root, tab.focusedLeafId) : null;
@@ -120,7 +113,6 @@ export function createMultiView(opts: MultiViewOptions): MultiView {
     sidebar.setHighlights({
       open: openSessions(layout),
       focused: focusedLeafSession(),
-      colors: colorMap(),
     });
   }
 
@@ -142,10 +134,7 @@ export function createMultiView(opts: MultiViewOptions): MultiView {
     const pane = document.createElement("div");
     pane.className = "mv-pane";
     pane.dataset.leafId = leaf.id;
-    if (leaf.sessionId) {
-      pane.dataset.sessionId = leaf.sessionId;
-      pane.style.setProperty("--mv-color", sessionColor(leaf.sessionId));
-    }
+    if (leaf.sessionId) pane.dataset.sessionId = leaf.sessionId;
 
     const host = document.createElement("div");
     host.className = "mv-pane-host";
@@ -482,7 +471,7 @@ export function createMultiView(opts: MultiViewOptions): MultiView {
       pool.setVisible([]);
       pool.setFocus(null);
       canvas.appendChild(renderWelcome());
-      sidebar.setHighlights({ open: openSessions(layout), focused: null, colors: colorMap() });
+      sidebar.setHighlights({ open: openSessions(layout), focused: null });
       persist();
       return;
     }
@@ -523,7 +512,6 @@ export function createMultiView(opts: MultiViewOptions): MultiView {
         pill.type = "button";
         pill.className = "mv-pill" + (l.id === focused.id ? " is-active" : "");
         pill.textContent = l.sessionId ? (infoFor(l.sessionId)?.name ?? l.sessionId.slice(0, 8)) : "empty";
-        if (l.sessionId) pill.style.setProperty("--mv-color", sessionColor(l.sessionId));
         pill.addEventListener("click", () => {
           tab.focusedLeafId = l.id;
           render();
@@ -543,7 +531,7 @@ export function createMultiView(opts: MultiViewOptions): MultiView {
       focused.sessionId ? [{ id: focused.sessionId, pane: pane.host, info: infoFor(focused.sessionId) }] : [],
     );
     pool.setFocus(focused.sessionId ?? null);
-    sidebar.setHighlights({ open: openSessions(layout), focused: focused.sessionId ?? null, colors: colorMap() });
+    sidebar.setHighlights({ open: openSessions(layout), focused: focused.sessionId ?? null });
   }
 
   function closeSession(sessionId: string): void {
diff --git a/web/src/sessioncolor.ts b/web/src/sessioncolor.ts
deleted file mode 100644
index a61caab..0000000
--- a/web/src/sessioncolor.ts
+++ /dev/null
@@ -1,23 +0,0 @@
-// Stable per-session accent colour, used to map a sidebar row to the pane
-// showing that session (issue #33). Hash the session id into a fixed OKLCH
-// palette tuned to the maestro tokens; collisions are tolerated when there are
-// more open sessions than hues — the colour is a hint, not an identity.
-
-import type { Uuid } from "./types.js";
-
-const PALETTE = [
-  "oklch(0.80 0.13 152)", // green (the house accent)
-  "oklch(0.80 0.12 90)", // amber
-  "oklch(0.76 0.13 30)", // coral
-  "oklch(0.78 0.11 210)", // teal
-  "oklch(0.74 0.13 265)", // blue
-  "oklch(0.76 0.14 320)", // magenta
-  "oklch(0.80 0.11 60)", // gold
-  "oklch(0.78 0.12 185)", // cyan
-];
-
-export function sessionColor(id: Uuid): string {
-  let h = 0;
-  for (let i = 0; i < id.length; i++) h = (h * 31 + id.charCodeAt(i)) >>> 0;
-  return PALETTE[h % PALETTE.length];
-}
diff --git a/web/src/styles.css b/web/src/styles.css
index ead281d..da97551 100644
--- a/web/src/styles.css
+++ b/web/src/styles.css
@@ -1059,6 +1059,46 @@ input.leaf-rename:focus {
    truncation target when even the complete trailing set cannot fit. */
 .leaf-cmd {
   flex: 0 1 auto;
+  display: inline-flex;
+  align-items: center;
+  gap: 4px;
+  min-width: 0;
+}
+
+/* The tool's mark stands in for the program the command line starts with
+   (docs/SIDEBAR.md). It keeps its own colours where the tool has brand
+   colours, and inherits the muted fragment colour where it does not. */
+.tool-icon {
+  flex: 0 0 auto;
+  opacity: 0.9;
+}
+
+.leaf-cmd-rest {
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+/* Blocked work as diff notation: `+124 -18 ?3 ↑2` (docs/SIDEBAR.md). The
+   spelled-out breakdown is the tooltip; only the additions and deletions take
+   colour, so the ⚠-less fragment still reads as a diff and not as an alarm. */
+.leaf-blocked {
+  display: inline-flex;
+  align-items: center;
+  gap: 4px;
+  font-variant-numeric: tabular-nums;
+}
+
+.blocked-stat[data-stat="add"] {
+  color: var(--live);
+}
+.blocked-stat[data-stat="del"] {
+  color: var(--danger);
+}
+.blocked-stat[data-stat="files"],
+.blocked-stat[data-stat="untracked"],
+.blocked-stat[data-stat="unpushed"] {
+  color: var(--faint);
 }
 
 /* Actions live in line 1's flow at its right edge — never overlaid on the
@@ -2313,20 +2353,10 @@ input.leaf-rename:focus {
   min-width: 0;
   min-height: 0;
 }
-/* per-session colour strip — maps a pane to its sidebar row */
-.mv-pane::before {
-  content: "";
-  position: absolute;
-  inset: 0 0 auto 0;
-  height: 2px;
-  background: var(--mv-color, transparent);
-  z-index: 3;
-  pointer-events: none;
-}
-/* focused pane: accent ring + glow, full strength */
+/* focused pane: accent ring, full strength */
 .mv-pane.is-focused {
   border-color: var(--accent);
-  box-shadow: inset 0 0 0 1px var(--accent), 0 0 22px -8px var(--accent-ring);
+  box-shadow: inset 0 0 0 1px var(--accent);
 }
 /* unfocused panes recede so the eye finds the live one */
 .mv-pane:not(.is-focused) {
@@ -2429,31 +2459,12 @@ input.leaf-rename:focus {
   border-radius: var(--r-1);
 }
 
-/* sidebar two-tier highlight + colour dot (issue #33).
+/* sidebar two-tier highlight (issue #33).
    .is-active = focused pane (loud, from existing rule); .is-open = open
-   elsewhere (quiet). The dot uses the session's colour so a row maps to a pane. */
+   elsewhere (quiet). */
 .tree-leaf.is-open {
   background: color-mix(in oklab, var(--accent) 6%, transparent);
 }
-.tree-leaf.is-open::after,
-.tree-leaf.is-active::after {
-  content: "";
-  position: absolute;
-  right: 9px;
-  top: 50%;
-  width: 7px;
-  height: 7px;
-  margin-top: -3.5px;
-  border-radius: 50%;
-  background: var(--mv-color, var(--accent));
-  pointer-events: none;
-}
-.tree-leaf.is-open::after {
-  opacity: 0.7;
-}
-.tree-leaf.is-active::after {
-  box-shadow: 0 0 8px var(--mv-color, var(--accent-ring));
-}
 
 /* =========================================================================
    multi-view mobile (#35): below 860px the split tree projects to a pill strip
@@ -2498,14 +2509,6 @@ input.leaf-rename:focus {
   cursor: pointer;
   border: 1px solid transparent;
 }
-.mv-pill::before {
-  content: "";
-  width: 7px;
-  height: 7px;
-  border-radius: 50%;
-  background: var(--mv-color, var(--faint));
-  flex: none;
-}
 .mv-pill.is-active {
   background: var(--accent-tint);
   color: var(--accent-strong);
diff --git a/web/src/toolIcon.test.ts b/web/src/toolIcon.test.ts
new file mode 100644
index 0000000..0af0745
--- /dev/null
+++ b/web/src/toolIcon.test.ts
@@ -0,0 +1,58 @@
+import { describe, expect, it } from "vitest";
+import { splitCommand, toolIconSvg } from "./toolIcon.js";
+
+describe("tool icons on the command fragment (docs/SIDEBAR.md)", () => {
+  it("recognises the agents and shells sessions are spawned with", () => {
+    const cases: Array<[string, string]> = [
+      ["claude", "claude"],
+      ["codex", "codex"],
+      ["opencode", "opencode"],
+      ["gemini", "gemini"],
+      ["aider", "aider"],
+      ["cursor-agent", "cursor"],
+      ["pi", "pi"],
+      ["zsh", "shell"],
+      ["bash", "shell"],
+      ["fish", "shell"],
+    ];
+    for (const [command, tool] of cases) {
+      expect(splitCommand(command).tool, command).toBe(tool);
+    }
+  });
+
+  it("keeps everything after the program as text", () => {
+    expect(splitCommand("claude --resume -p hi")).toEqual({
+      tool: "claude",
+      rest: "--resume -p hi",
+    });
+    expect(splitCommand("  zsh   -l  ")).toEqual({ tool: "shell", rest: "-l" });
+  });
+
+  it("looks through paths, env assignments and wrappers", () => {
+    expect(splitCommand("/usr/local/bin/claude").tool).toBe("claude");
+    expect(splitCommand("FOO=1 BAR=2 claude").tool).toBe("claude");
+    expect(splitCommand("npx opencode").tool).toBe("opencode");
+    expect(splitCommand("pnpm dlx opencode run").tool).toBe("opencode");
+    expect(splitCommand("pnpm dlx opencode run").rest).toBe("run");
+  });
+
+  it("leaves an unrecognised program as text, mark-less", () => {
+    expect(splitCommand("hx src/main.rs")).toEqual({
+      tool: null,
+      rest: "hx src/main.rs",
+    });
+    // A wrapper with nothing after it is not a tool either.
+    expect(splitCommand("sudo").tool).toBeNull();
+    expect(splitCommand("").tool).toBeNull();
+  });
+
+  it("gives every recognised tool a labelled mark", () => {
+    for (const tool of ["claude", "codex", "opencode", "gemini", "aider", "cursor", "pi", "shell"]) {
+      const svg = toolIconSvg(tool);
+      expect(svg, tool).toContain("<svg");
+      expect(svg, tool).toContain(`data-tool="${tool}"`);
+      expect(svg, tool).toContain("aria-label=");
+    }
+    expect(toolIconSvg("nonesuch")).toBeNull();
+  });
+});
diff --git a/web/src/toolIcon.ts b/web/src/toolIcon.ts
new file mode 100644
index 0000000..3c57759
--- /dev/null
+++ b/web/src/toolIcon.ts
@@ -0,0 +1,141 @@
+/** Tool icons for the sidebar's command fragment (docs/SIDEBAR.md).
+ *
+ * A session's command line starts with the program that runs it, and that
+ * program is nearly always one of a handful of agents or a shell. Rendering it
+ * as its own mark buys back most of the fragment's width, which the sidebar
+ * spends on the rest of the command line instead.
+ *
+ * Recognition is deliberately narrow: an unrecognised program keeps its text,
+ * so the fragment never renders a mark that stands for the wrong tool.
+ */
+
+/** Command wrappers that run another program: the tool is what follows. */
+const WRAPPERS = new Set(["sudo", "env", "npx", "bunx", "uvx", "pnpm", "yarn", "command"]);
+
+/** Program name (already basenamed and lowercased) → icon id. */
+const BY_PROGRAM: Record<string, string> = {
+  claude: "claude",
+  "claude-code": "claude",
+  codex: "codex",
+  opencode: "opencode",
+  gemini: "gemini",
+  aider: "aider",
+  cursor: "cursor",
+  "cursor-agent": "cursor",
+  pi: "pi",
+  bash: "shell",
+  zsh: "shell",
+  sh: "shell",
+  fish: "shell",
+  dash: "shell",
+  ksh: "shell",
+  nu: "shell",
+  xonsh: "shell",
+};
+
+/** Human name behind an icon id, for the tooltip and the aria label. */
+export const TOOL_LABELS: Record<string, string> = {
+  claude: "Claude Code",
+  codex: "Codex",
+  opencode: "opencode",
+  gemini: "Gemini CLI",
+  aider: "Aider",
+  cursor: "Cursor",
+  pi: "pi",
+  shell: "Shell",
+};
+
+export interface CommandParts {
+  /** Icon id, or `null` when the program is not one we have a mark for. */
+  tool: string | null;
+  /** What is left of the command line once the icon stands for the program.
+   * Empty when the icon says everything the command line said. */
+  rest: string;
+}
+
+/** Split a command line into the tool its icon stands for and the remainder.
+ *
+ * `claude --resume` → `{tool: "claude", rest: "--resume"}`; an unrecognised
+ * `hx src/` keeps the whole line as `rest` with no tool. */
+export function splitCommand(command: string): CommandParts {
+  const words = command.trim().split(/\s+/).filter(Boolean);
+  let i = 0;
+  // Leading `FOO=bar` assignments and wrappers stand in front of the real
+  // program; `pnpm dlx x` / `yarn dlx x` need one more word skipped.
+  while (i < words.length) {
+    const word = words[i];
+    if (/^[A-Za-z_][A-Za-z0-9_]*=/.test(word)) {
+      i += 1;
+      continue;
+    }
+    const program = basename(word);
+    if (WRAPPERS.has(program)) {
+      i += 1;
+      if ((program === "pnpm" || program === "yarn") && words[i] === "dlx") i += 1;
+      continue;
+    }
+    break;
+  }
+  if (i >= words.length) return { tool: null, rest: command.trim() };
+  const tool = BY_PROGRAM[basename(words[i])] ?? null;
+  if (!tool) return { tool: null, rest: command.trim() };
+  return { tool, rest: words.slice(i + 1).join(" ") };
+}
+
+function basename(word: string): string {
+  const cut = word.lastIndexOf("/");
+  return (cut >= 0 ? word.slice(cut + 1) : word).toLowerCase();
+}
+
+/** Anthropic's burst: tapered rays around a centre, long ones on the axes. */
+function burst(): string {
+  const rays = Array.from({ length: 8 }, (_, k) => {
+    const long = k % 2 === 0;
+    const tip = long ? 1.1 : 3.4;
+    const waist = long ? 6.3 : 6.6;
+    const half = long ? 1.05 : 0.85;
+    return `<path d="M8 ${tip} L${8 + half} ${waist} L8 8 L${8 - half} ${waist} Z" transform="rotate(${k * 45} 8 8)"/>`;
+  }).join("");
+  return `<g fill="#d97757">${rays}</g>`;
+}
+
+const SVGS: Record<string, string> = {
+  claude: burst(),
+  // A hexafoil knot in the shape of OpenAI's mark. The petals stay thin and
+  // wide apart: three fatter loops merge into a blob at 13px.
+  codex: `<g fill="none" stroke="currentColor" stroke-width="1.05">
+    <ellipse cx="8" cy="8" rx="2.5" ry="6.7"/>
+    <ellipse cx="8" cy="8" rx="2.5" ry="6.7" transform="rotate(60 8 8)"/>
+    <ellipse cx="8" cy="8" rx="2.5" ry="6.7" transform="rotate(120 8 8)"/>
+  </g>`,
+  gemini: `<path fill="#4285f4" d="M8 0.8C8.6 4.6 11.4 7.4 15.2 8C11.4 8.6 8.6 11.4 8 15.2C7.4 11.4 4.6 8.6 0.8 8C4.6 7.4 7.4 4.6 8 0.8Z"/>`,
+  // An isometric cube, the shape Cursor's mark is built from.
+  cursor: `<g fill="currentColor">
+    <path d="M8 1 L14.5 4.75 L8 8.5 L1.5 4.75 Z" opacity="0.95"/>
+    <path d="M14.5 4.75 L14.5 12.25 L8 16 L8 8.5 Z" opacity="0.5"/>
+    <path d="M1.5 4.75 L8 8.5 L8 16 L1.5 12.25 Z" opacity="0.75"/>
+  </g>`,
+  shell: `<g fill="none" stroke="currentColor" stroke-width="1.6" stroke-linecap="round" stroke-linejoin="round">
+    <path d="M2.6 4 L6.4 8 L2.6 12"/>
+    <path d="M8.4 12.6 H13.4"/>
+  </g>`,
+  opencode: monogram("oc"),
+  aider: monogram("ai"),
+  pi: monogram("π"),
+};
+
+/** Tools whose own mark is a wordmark get their initials instead — inventing
+ * a logo for them would be worse than saying which letters they start with.
+ * No chip around the letters: a border this small eats the height the letters
+ * need to stay apart. */
+function monogram(text: string): string {
+  return `<text x="8" y="8.6" fill="currentColor" font-family="ui-monospace, SFMono-Regular, Menlo, monospace" font-size="11" font-weight="700" letter-spacing="-0.6" text-anchor="middle" dominant-baseline="central">${text}</text>`;
+}
+
+/** The `<svg>` for an icon id, or `null` when the id has no mark. */
+export function toolIconSvg(tool: string): string | null {
+  const body = SVGS[tool];
+  if (!body) return null;
+  const label = TOOL_LABELS[tool] ?? tool;
+  return `<svg class="tool-icon" data-tool="${tool}" viewBox="0 0 16 16" width="13" height="13" role="img" aria-label="${label}"><title>${label}</title>${body}</svg>`;
+}
diff --git a/web/src/types.ts b/web/src/types.ts
index 3e95848..c86ceb8 100644
--- a/web/src/types.ts
+++ b/web/src/types.ts
@@ -164,6 +164,42 @@ export interface InTheWay {
   uncommitted_files?: number;
   untracked_files?: number;
   unpushed_commits?: number;
+  /** Lines added across the tracked changes, staged and unstaged together. */
+  insertions?: number;
+  /** Lines removed across the same tracked changes. */
+  deletions?: number;
+}
+
+/** One fragment of the sidebar's compact blocked-work stat (docs/SIDEBAR.md).
+ * `kind` picks the colour; `text` is what the client prints. */
+export interface BlockerStat {
+  kind: "add" | "del" | "files" | "untracked" | "unpushed";
+  text: string;
+}
+
+/** The blocked-work breakdown as diff notation: `+124 -18 ?3 ↑2`.
+ *
+ * The line counts cover tracked changes only, so a tree whose only tracked
+ * change carries no line delta — a mode change, a rename — falls back to the
+ * file count (`~2`) rather than claiming `+0 -0`. Both clients render exactly
+ * these fragments; the spelled-out {@link formatInTheWay} survives in the
+ * tooltip and in the kill refusal. */
+export function blockerStats(w: InTheWay): BlockerStat[] {
+  const stats: BlockerStat[] = [];
+  const added = w.insertions ?? 0;
+  const removed = w.deletions ?? 0;
+  const changed = w.uncommitted_files ?? 0;
+  if (added > 0 || removed > 0) {
+    if (added > 0) stats.push({ kind: "add", text: `+${added}` });
+    if (removed > 0) stats.push({ kind: "del", text: `-${removed}` });
+  } else if (changed > 0) {
+    stats.push({ kind: "files", text: `~${changed}` });
+  }
+  if ((w.untracked_files ?? 0) > 0)
+    stats.push({ kind: "untracked", text: `?${w.untracked_files}` });
+  if ((w.unpushed_commits ?? 0) > 0)
+    stats.push({ kind: "unpushed", text: `\u2191${w.unpushed_commits}` });
+  return stats;
 }
 
 /** The phrasing `maestro_protocol::InTheWay`'s Display impl uses — shared by