fix: handle web console segment rotation

.yoi/tickets/00001KY1ZKCPC/item.md

@@ -2,7 +2,7 @@
 title: 'Backend runtime経由の操作をprotocol transportへ統一しTUI同等にする'
 state: 'planning'
 created_at: '2026-07-21T09:20:07Z'
-updated_at: '2026-07-22T05:03:17Z'
+updated_at: '2026-07-22T06:36:51Z'
 assignee: null
 readiness: 'draft'
 ---

.yoi/tickets/00001KY1ZKCPC/thread.md

@@ -341,3 +341,38 @@ Verification:
 - `git diff --check`
 
 ---
+
+<!-- event: comment author: assistant at: 2026-07-22T06:25:37Z -->
+
+## Comment
+
+Reported issue before implementation:
+
+- TUI shows the `Compacting...` progress/status indication.
+- Web Console does not show the same indication.
+
+Investigation plan:
+- Compare TUI protocol/event handling with Web Console protocol/event handling.
+- Confirm whether the relevant protocol event reaches the browser and is dropped by frontend state/rendering, or whether the event is not forwarded through the Backend/runtime protocol WS path.
+- Fix the narrow missing mapping/rendering path without adding a synthetic event outside the normal Worker protocol/session flow.
+
+---
+
+<!-- event: implementation_report author: assistant at: 2026-07-22T06:36:51Z -->
+
+## Implementation report
+
+Implementation report for Web Console compact/rotation display gap:
+
+- Web Console already handled live `compact_start` by projecting a `Compacting…` status row.
+- The projection was still ignoring `segment_rotated`, while TUI reseeds the visible transcript from the new segment start entry. This made Web diverge around compaction/segment-rotation boundaries.
+- Updated `web/workspace/src/lib/workspace/console/model.ts` so `segment_rotated` reprojects `event.data.entry` through the same log-entry projection path used by `snapshot`.
+- Added a Web projection regression test asserting `segment_rotated` replaces stale visible rows with the new segment seed.
+- While running Web check, fixed a narrow `list_completions` TypeScript narrowing issue in `+page.svelte`: command completions return early, then the file completion kind/prefix are captured before the Promise closure.
+
+Verification:
+- `cd web/workspace && deno test --allow-read=src --allow-env=VSCODE_TEXTMATE_DEBUG src/lib/workspace/console/model.test.ts`
+- `cd web/workspace && deno task check` passes with 0 errors; it still reports 2 existing a11y warnings in `+page.svelte`.
+- `git diff --check`
+
+---

web/workspace/src/lib/workspace/console/model.test.ts

@@ -818,3 +818,42 @@ Deno.test("projectConsole renders snapshot entries and in-flight output", () =>
     ],
   );
 });
+
+Deno.test("projectConsole reseeds visible rows from segment rotation", () => {
+  const projection = projectConsole([
+    {
+      eventId: "rotation-before",
+      event: {
+        event: "user_message",
+        data: { segments: [{ kind: "text", content: "before rotation" }] },
+      } satisfies Event,
+    },
+    {
+      eventId: "rotation-event",
+      event: {
+        event: "segment_rotated",
+        data: {
+          entry: {
+            kind: "segment_start",
+            ts: 10,
+            session_id: "00000000-0000-0000-0000-000000000001",
+            system_prompt: null,
+            config: {},
+            history: [
+              {
+                kind: "message",
+                role: "user",
+                content: [{ kind: "text", text: "after rotation seed" }],
+              },
+            ],
+          },
+        },
+      } satisfies Event,
+    },
+  ]);
+
+  assertEquals(
+    projection.lines.map((line) => `${line.kind}:${line.body}`),
+    ["user:after rotation seed"],
+  );
+});

web/workspace/src/lib/workspace/console/model.ts

@@ -259,6 +259,9 @@ export function applyProtocolEvent(
     case "status":
       next.status = event.data.status;
       break;
+    case "segment_rotated":
+      next.lines = snapshotLinesFromEntries(envelope.eventId, [event.data.entry]);
+      break;
     case "invoke_start":
     case "turn_start":
     case "turn_end":
@@ -272,7 +275,6 @@ export function applyProtocolEvent(
       appendAlertLine(next, envelope.eventId, event.data);
       break;
     case "memory_worker":
-    case "segment_rotated":
     case "completions":
     case "rewind_targets":
     case "rewind_applied":

web/workspace/src/routes/w/[workspaceId]/runtimes/[runtimeId]/workers/[workerId]/console/+page.svelte

@@ -324,6 +324,8 @@
         if (token.kind === "command") {
             return localCommandCompletions(token.prefix);
         }
+        const completionKind = token.kind;
+        const completionPrefix = token.prefix;
         return new Promise((resolve, reject) => {
             if (pendingCompletionRequest) {
                 rejectPendingCompletion(
@@ -339,7 +341,7 @@
             try {
                 sendProtocolMethod({
                     method: "list_completions",
-                    params: { kind: token.kind, prefix: token.prefix },
+                    params: { kind: completionKind, prefix: completionPrefix },
                 });
             } catch (error) {
                 rejectPendingCompletion(