diff --git a/docs/SIDEBAR.md b/docs/SIDEBAR.md
index 55cbd49..1ac2442 100644
--- a/docs/SIDEBAR.md
+++ b/docs/SIDEBAR.md
@@ -41,13 +41,20 @@ Otherwise line 2 is absent — never an empty placeholder row.
 When present, line 2 reads left to right:
 
 ```
-<dot> <duration> [<blocked work> | exited]
+<dot> <duration> [<blocked work> | exited] [<command>]
 ```
 
 `<dot>` is a single filled glyph (`●` on both clients) carrying the activity
 state's colour, and `<duration>` follows in the same colour. There is no state
 word and no second badge: the dot exists so the state is still legible when a
-row is dimmed or the terminal renders the duration in the default fg.
+row is dimmed or the terminal renders the duration in the default fg. The dot
+and duration are unconditional parts of line 2; the bracketed fragments appear
+only when their trigger holds. A payload that predates #102 (no usable
+`activity_since`) contributes no duration — the dot still renders.
+
+`<command>` is optional and muted: the session's command line, shown only when
+the rendered name came from `metadata.name` and differs from the command (the
+web has always surfaced this; the TUI may omit it).
 
 ## Colour per activity state
 
@@ -65,9 +72,9 @@ and `prefers-color-scheme` variants for each). The TUI uses the plain ratatui
 named colours above; do not introduce RGB values or a new palette module for
 this.
 
-The duration text inherits its state's colour; the blocked-work and exited
-fragments use the muted colour (`--faint` / default style), since the ⚠ glyph
-already signals severity.
+The duration text inherits its state's colour; the blocked-work, exited and
+command fragments use the muted colour (`--faint` / default style), since the
+⚠ glyph already signals severity.
 
 ## Duration format