fix(omp): report the conversation a /resume switches to

CHANGELOG.md

@@ -7,6 +7,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+
+- **An omp session that resumes another conversation tells lich which.** A
+  `/resume` inside omp left lich holding the conversation the card opened
+  with, so a restart resumed the old one and lich could not warn when the
+  conversation was already open in another card. The switch is now reported
+  as it happens.
+
 ## [0.20.4] - 2026-10-16
 
 ### Fixed

docs/providers.md

@@ -74,7 +74,7 @@ swallows its own errors and never awaits a report.
 
 | Report              | Claude Code                  | Codex                        | Antigravity                  | opencode                  | omp                      | Crush                       |
 |---------------------|------------------------------|------------------------------|------------------------------|---------------------------|--------------------------|-----------------------------|
-| session id          | `SessionStart`               | `SessionStart`               | `PreInvocation`              | `session.created`         | `session_start`          | `PreToolUse`                |
+| session id          | `SessionStart`               | `SessionStart`               | `PreInvocation`              | `session.created`         | `session_start`, `session_switch` | `PreToolUse`       |
 | `busy`              | `UserPromptSubmit`, `PostToolUse` | `UserPromptSubmit`, `PostToolUse` | `PreInvocation`        | `session.status` (`busy`) | `input`, `turn_start` | —              |
 | `busy` + tool       | `PreToolUse`                 | `PreToolUse`                 | `PreToolUse`                 | `tool.execute.before`     | `tool_call`              | —                           |
 | `waiting` + reason  | `Notification`               | `PermissionRequest`          | — (not measured)             | any `*.asked`             | — (see below)            | —                           |

docs/session-start.md

@@ -10,7 +10,7 @@ the *provider* session id — the field is provider-agnostic.
 
 | script                             | action                          | Claude Code hook | Codex hook     | Antigravity hook | opencode event    | omp event       | Crush hook   |
 |------------------------------------|---------------------------------|------------------|----------------|------------------|-------------------|-----------------|--------------|
-| `report-session-start.sh <provider>` | send the CLI's `session_id`   | `SessionStart`   | `SessionStart` | `PreInvocation`  | `session.created` | `session_start` | `PreToolUse` |
+| `report-session-start.sh <provider>` | send the CLI's `session_id`   | `SessionStart`   | `SessionStart` | `PreInvocation`  | `session.created` | `session_start`, `session_switch` | `PreToolUse` |
 
 `POST /session-start` with `{"session_id": $LICH_SESSION_ID,
 "provider_session_id": <session_id/conversationId from the hook payload on stdin>, "provider":
@@ -41,7 +41,10 @@ The module harnesses report from the earliest place each offers. opencode raises
 `session.created` before the first turn, as early as `SessionStart`; omp's
 `session_start` fires at the same point, and the id itself is read off
 `ctx.sessionManager.getSessionId()` rather than off the event, which carries
-nothing but its type. **Crush only has `PreToolUse`**, so its id rides the first
+nothing but its type. A `/resume` inside omp switches conversations with no
+second `session_start`: omp emits `session_switch` (reason `resume`, measured on
+18.8.9), by which point the manager already answers with the new id, so that
+event reports too. **Crush only has `PreToolUse`**, so its id rides the first
 tool call and a conversation that answers without a tool never sends one — late,
 not wrong.
 

omp/lich.js

@@ -115,13 +115,16 @@ export default function lichPlugin(pi) {
   // The session id lich resumes from. It is on the manager rather than in the
   // environment: omp exports nothing about the running session to its own
   // process env, so `ctx` is the only source.
-  pi.on(
-    "session_start",
-    safely((_event, ctx) => {
-      const id = sessionIdOf(ctx)
-      if (id !== undefined) report("session-start", { provider_session_id: id, provider: "omp" })
-    }),
-  )
+  const reportStart = safely((_event, ctx) => {
+    const id = sessionIdOf(ctx)
+    if (id !== undefined) report("session-start", { provider_session_id: id, provider: "omp" })
+  })
+  pi.on("session_start", reportStart)
+  // A `/resume` moves the session onto another conversation with no second
+  // `session_start`: omp emits `session_switch` instead, its manager already
+  // on the new id (measured on 18.8.9). Reported like a start, so lich holds
+  // the conversation the card runs now.
+  pi.on("session_switch", reportStart)
 
   // The user has sent something: the turn starts here in an interactive
   // session, which is the only kind lich spawns.

tests/omp.test.mjs

@@ -130,6 +130,23 @@ test('session_start with no id yet reports nothing', async () => {
   assert.equal(requests.length, 0, `posted an empty provider session id: ${requests[0]?.raw}`)
 })
 
+// A `/resume` inside omp moves the session onto another conversation without
+// a second `session_start`: omp 18.8.9 emits `session_before_switch` and then
+// `session_switch` (reason "resume"), measured with a logger extension, and
+// by the second one the manager already answers with the new id. lich keeps
+// the id of the conversation running in the card, and warns when another card
+// runs it too, so the switch is reported like a start.
+test('session_switch reports the conversation switched to', async () => {
+  const switched = '0000000b-0000-7000-9000-00000000000b'
+  const requests = await reportsFor(({ emit }) =>
+    emit('session_switch', { type: 'session_switch', reason: 'resume' }, ctxWith({ id: switched })),
+  )
+  assert.equal(requests.length, 1)
+  const { body } = assertSessionStart(requests[0])
+  assert.equal(body.provider, 'omp')
+  assert.equal(body.provider_session_id, switched)
+})
+
 test('input reports busy', async () => {
   const requests = await reportsFor(({ emit }) =>
     emit('input', { type: 'input', text: 'ship it', source: 'interactive' }, ctxWith()),