feat: show the edit guard's note to the user in the status line

CHANGELOG.md

@@ -7,6 +7,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- **The edit guard tells you too, not only the model.** When a file you edit
+  was also edited by another lich session in the last 10 minutes, the status
+  line under the prompt reads `lich: app.js also edited by "quiet-comet"` until
+  that edit leaves the window. It shares the line with the worker count:
+  `lich: 2 workers · app.js also edited by "quiet-comet"`.
+
 ## [0.17.0] - 2026-10-05
 
 ### Added

CLAUDE.md

@@ -23,6 +23,7 @@ hooks/agent-cards.js              # Claude Code mod: a general-purpose subagent
 hooks/mod-usage.js                # Claude Code mod: the session reports its own context, rate limits and cost
 hooks/edit-guard.js               # Claude Code mod: an edit says which other lich session edited the file
 hooks/worker-answer.js            # Claude Code mod: a lich subagent worker's last message answers its task
+hooks/status-line.js              # the one status line Claude Code gives the plugin, shared by the mods above
 opencode/lich.js                  # opencode client: a module, not a command
 omp/lich.js                       # omp client: a module, not a command
 docs/                             # lich ⇄ plugin communication contracts
@@ -101,7 +102,9 @@ usage reports against the mod-usage fixtures, and
 answer against the mod-answer fixtures.
 [tests/edit-guard.test.mjs](tests/edit-guard.test.mjs) hands the edit guard a
 fake `$` with an in-memory git dir and asserts the markers it leaves and the
-note another session's marker adds.
+note another session's marker adds, and
+[tests/status-line.test.mjs](tests/status-line.test.mjs) that the mods share
+the one status line Claude Code gives the plugin.
 [tests/agent-cards.test.mjs](tests/agent-cards.test.mjs) hands the agent-cards
 mod the same kind of fake `$` and asserts the `lich open` argv
 it runs, the Agent result it answers each outcome with, and that a call it does

docs/edit-guard.md

@@ -52,6 +52,12 @@ unless `LICH_SESSION_ID` is set.
    after the tool's result: the path, the session, the time and how long
    ago, and that `send_to_session` or `lich send` reaches that session. A
    refused call carries the line too, since it explains the refusal.
+6. The same edit puts `<file name> also edited by <session>` in the status
+   line under the prompt, for the user, who never reads the `context` line.
+   It stays until the marker leaves the 10-minute window, or a newer one
+   replaces it. Claude Code keeps one status line per plugin, so it shares the
+   line with the worker count of [agent-cards.md](agent-cards.md), through
+   `hooks/status-line.js`.
 
 The line names the session by the label on its card, the name the user and
 `lich send` know it by. lich puts no label in a session's environment and no

hooks/agent-cards.js

@@ -22,6 +22,8 @@
 // Every function that takes `$` is declared at the top level: the loader
 // refuses a module that hands `$` to a nested function or keeps it in a variable.
 
+import { statusLineWith } from "./status-line.js"
+
 // lich's `promptLimit` (internal/relay). lich checks it only after the session
 // was opened, so a task over it would leave an empty card behind.
 const PROMPT_LIMIT_BYTES = 8192
@@ -334,7 +336,7 @@ async function runAsSession($, state, e, next) {
  */
 function showWorkers($, state) {
   const count = state.workers.size
-  $.ui.status(count === 0 ? undefined : `${count} worker${count === 1 ? "" : "s"}`)
+  $.ui.status(statusLineWith("workers", count === 0 ? undefined : `${count} worker${count === 1 ? "" : "s"}`))
 }
 
 /**

hooks/edit-guard.js

@@ -11,6 +11,8 @@
 // Every function that takes `$` is declared here at the top level: the loader
 // refuses a module that hands `$` to a nested function.
 
+import { statusLineWith } from "./status-line.js"
+
 // Long enough to span the other session's turn that made the edit, short
 // enough that a marker from work long finished stops raising notes.
 const RECENT_MS = 10 * 60_000
@@ -116,20 +118,46 @@ function noteFor(marker, who, now) {
 }
 
 /**
- * The note for `marker`, naming its session by label when lich can say which.
+ * The session that left `marker`, by label when lich can say which.
  *
  * @param {Engine} $
  * @param {Marker} marker
- * @param {number} now
  */
-async function noteNaming($, marker, now) {
+async function whoMarked($, marker) {
   let label
   try {
     label = await labelOf($, marker.session)
   } catch (error) {
     logFailure($, error)
   }
-  return noteFor(marker, label ? `"${label}"` : marker.session, now)
+  return label ? `"${label}"` : marker.session
+}
+
+/** The marker the status line shows, so an older one's timer does not clear a newer one. @type {Marker | undefined} */
+let shownMarker
+
+/**
+ * Tells the user too, in the status line, until the marker stops being news.
+ * The note only reaches the model.
+ *
+ * @param {Engine} $
+ * @param {Marker} marker
+ * @param {string} who
+ */
+function showEditBy($, marker, who) {
+  shownMarker = marker
+  const name = marker.path.slice(Math.max(marker.path.lastIndexOf("/"), marker.path.lastIndexOf("\\")) + 1)
+  $.ui.status(statusLineWith("edits", `${name} also edited by ${who}`))
+}
+
+/**
+ * @param {Engine} $
+ * @param {Marker} marker
+ */
+function clearEditBy($, marker) {
+  if (shownMarker !== marker) return
+  shownMarker = undefined
+  $.ui.status(statusLineWith("edits", undefined))
 }
 
 /** @param {Engine} $ @param {unknown} error */
@@ -163,7 +191,12 @@ async function guard($, e, next) {
   let note
   try {
     const now = await $.clock.now()
-    if (isNews(previous, session, now)) note = await noteNaming($, previous, now)
+    if (isNews(previous, session, now)) {
+      const who = await whoMarked($, previous)
+      note = noteFor(previous, who, now)
+      showEditBy($, previous, who)
+      $.clock.after(previous.at + RECENT_MS - now, () => clearEditBy($, previous))
+    }
     if (!result.isError) await $.fs.write(markerPath, JSON.stringify({ path, session, at: now }))
   } catch (error) {
     logFailure($, error)

hooks/status-line.js

@@ -0,0 +1,28 @@
+// The lich status line under the prompt, shared by the mods. Claude Code keeps
+// one `$.ui.status` line per plugin and every mod here is the plugin `lich`, so
+// a mod that set it directly would wipe what another mod put there. Each mod
+// owns one part instead, and the line is the parts joined in a fixed order.
+
+/** @typedef {"workers" | "edits"} Part */
+
+/** @type {Part[]} */
+const ORDER = ["workers", "edits"]
+const SEPARATOR = " · "
+
+/** @type {Map<Part, string>} */
+const parts = new Map()
+
+/**
+ * The line with this mod's part set to `text`, undefined removing it; the
+ * caller passes it to `$.ui.status` itself, since the loader refuses `$`
+ * handed across an import. Undefined when no part is left, which clears it.
+ *
+ * @param {Part} part
+ * @param {string | undefined} text
+ */
+export function statusLineWith(part, text) {
+  if (text === undefined) parts.delete(part)
+  else parts.set(part, text)
+  const shown = ORDER.filter((p) => parts.has(p)).map((p) => parts.get(p))
+  return shown.length === 0 ? undefined : shown.join(SEPARATOR)
+}

tests/edit-guard.engine.test.ts

@@ -69,6 +69,22 @@ test('the note names the other session by the label on its card', async ($, on)
   expect(ran.context?.[0]).toContain('lich session "quiet-comet" at')
 })
 
+test('the user sees the other session in the status line', async ($, on) => {
+  const w = world(on, 'lich-a', [{ label: 'quiet-comet', name: 'repo-7c0e', project: 'repo', kind: 'claude', state: 'busy', id: B_ID }])
+  const statuses: (string | undefined)[] = []
+  on('ui.status', async (_$, e) => {
+    statuses.push(e.text)
+    return { value: undefined }
+  })
+  await $.tool.call(EDIT)
+  const [path] = markerOf(w.disk) ?? []
+  w.disk.set(path!, JSON.stringify({ path: FILE, session: B_ID, at: T0 - 60_000 }))
+
+  await $.tool.call(EDIT)
+
+  expect(statuses).toEqual(['app.js also edited by "quiet-comet"'])
+})
+
 test('outside lich the edit runs untouched and nothing is recorded', async ($, on) => {
   const w = world(on, undefined)
   const ran = await $.tool.call(EDIT)

tests/edit-guard.test.mjs

@@ -4,7 +4,8 @@
 // Like the other mod suites it imports the module and hands it a fake engine:
 // `$.fs` is an in-memory map, `$.process.run` answers `git rev-parse` for one
 // repository and `lich sessions --json` with the roster a test hands it,
-// `$.clock.now` is a number the test moves.
+// `$.clock.now` is a number the test moves, and a `$.clock.after` timer runs
+// when the test fires it.
 //
 // Run: node --test tests/
 
@@ -53,12 +54,20 @@ function session({
     hooks.set(matcher.tool, hook)
   })
   const logs = []
+  const statuses = []
+  const timers = []
   const env = id === undefined ? {} : { LICH_SESSION_ID: id, LICH_BIN: lich }
   const lichRuns = []
   const $ = {
     env: { get: async (name) => env[name] },
-    clock: { now: async () => clock.now },
-    ui: { log: (text) => logs.push(text) },
+    clock: {
+      now: async () => clock.now,
+      after: (ms, fn) => {
+        timers.push({ ms, fn })
+        return { cancel: () => {} }
+      },
+    },
+    ui: { log: (text) => logs.push(text), status: (text) => statuses.push(text) },
     process: {
       run: async (argv, options) => {
         if (argv[0] === LICH) {
@@ -96,6 +105,8 @@ function session({
     disk,
     clock,
     logs,
+    statuses,
+    timers,
     hooks,
     lichRuns,
     edit: (path = FILE) => call('Edit', { file_path: path, old_string: 'a', new_string: 'b' }),
@@ -303,6 +314,44 @@ test('the lich CLI runs only when a note is added', async () => {
   assert.equal(a.lichRuns.length, 0)
 })
 
+test('the user sees the other session in the status line until its marker leaves the window', async () => {
+  const { b } = await editedByAThenB({
+    roster: async () => ({ exitCode: 0, stdout: `${JSON.stringify([A_PEER])}\n`, stderr: '' }),
+  })
+
+  assert.deepEqual(b.statuses, ['app.js also edited by "quiet-comet"'])
+  assert.deepEqual(b.timers.map((t) => t.ms), [9 * MINUTE], 'cleared when the 10-minute window of A\'s edit ends')
+  b.timers[0].fn()
+  assert.deepEqual(b.statuses, ['app.js also edited by "quiet-comet"', undefined])
+})
+
+test('an older edit leaving the window does not clear a newer one from the status line', async () => {
+  const disk = new Map()
+  const clock = { now: T0 }
+  const a = session({ id: 'lich-a', disk, clock })
+  const b = session({ id: 'lich-b', disk, clock })
+  const other = `${REPO}/src/other.js`
+
+  await a.edit()
+  await a.edit(other)
+  clock.now = T0 + MINUTE
+  await b.edit()
+  await b.edit(other)
+  b.timers[0].fn()
+
+  assert.deepEqual(b.statuses, ['app.js also edited by lich-a', 'other.js also edited by lich-a'])
+})
+
+test('no note, no status line', async () => {
+  const a = session({ id: 'lich-a' })
+
+  await a.edit()
+  await a.edit()
+
+  assert.deepEqual(a.statuses, [])
+  assert.deepEqual(a.timers, [])
+})
+
 test('the plugin entry module registers the guard on every file-editing tool', () => {
   const tools = []
   registerEntry((event, matcher) => {

tests/status-line.test.mjs

@@ -0,0 +1,25 @@
+// Pins hooks/status-line.js: Claude Code keeps one status line per plugin, so
+// the mods' parts share it instead of overwriting each other.
+//
+// Run: node --test tests/
+
+import { test } from 'node:test'
+import assert from 'node:assert/strict'
+
+import { statusLineWith } from '../hooks/status-line.js'
+
+test('parts share the one line in a fixed order, and the line goes with the last part', () => {
+  const statuses = [
+    statusLineWith('edits', 'app.js also edited by "docs"'),
+    statusLineWith('workers', '2 workers'),
+    statusLineWith('edits', undefined),
+    statusLineWith('workers', undefined),
+  ]
+
+  assert.deepEqual(statuses, [
+    'app.js also edited by "docs"',
+    '2 workers · app.js also edited by "docs"',
+    '2 workers',
+    undefined,
+  ])
+})