refactor(team): narrow PR to progress payload cap only

Remove the SessionDetail.messages stripping and related cache-size
change per maintainer feedback. The session-detail optimization will
follow separately after PR #58 lands with the right architectural
pattern (lightweight snapshot + separate endpoints).

This PR now contains only:
- progressPayload helpers (buildProgressLogsTail, buildProgressAssistantOutput)
- cap applied to emitLogsProgress, updateProgress, stall warning, retry error
- throttle raised 300ms -> 1000ms
- tests for the progress payload behavior

src/main/http/sessions.ts

@@ -13,7 +13,6 @@
 import { createLogger } from '@shared/utils/logger';
 
 import { coercePageLimit, validateProjectId, validateSessionId } from '../ipc/guards';
-import { stripSessionDetailMessages } from '../services/analysis/sessionDetailPayload';
 import { DataCache } from '../services/infrastructure/DataCache';
 
 import type { SessionsByIdsOptions, SessionsPaginationOptions } from '../types';
@@ -189,11 +188,11 @@ export function registerSessionRoutes(app: FastifyInstance, services: HttpServic
       );
       session.hasSubagents = subagents.length > 0;
 
-      // Build session detail with chunks. Strip the raw `messages` array before
-      // caching/returning — the renderer only consumes chunks/processes/session,
-      // and including messages doubled IPC payload size and cache footprint.
-      sessionDetail = stripSessionDetailMessages(
-        services.chunkBuilder.buildSessionDetail(session, parsedSession.messages, subagents)
+      // Build session detail with chunks
+      sessionDetail = services.chunkBuilder.buildSessionDetail(
+        session,
+        parsedSession.messages,
+        subagents
       );
 
       // Cache the result
@@ -319,10 +318,10 @@ export function registerSessionRoutes(app: FastifyInstance, services: HttpServic
             parsedSession.messages
           );
 
-          // Strip the raw `messages` array before caching so the waterfall path
-          // cannot "poison" the cache entry reused by the session-detail route.
-          detail = stripSessionDetailMessages(
-            services.chunkBuilder.buildSessionDetail(session, parsedSession.messages, subagents)
+          detail = services.chunkBuilder.buildSessionDetail(
+            session,
+            parsedSession.messages,
+            subagents
           );
           services.dataCache.set(cacheKey, detail);
         }

src/main/ipc/sessions.ts

@@ -13,7 +13,6 @@ import { createLogger } from '@shared/utils/logger';
 import { type IpcMain, type IpcMainInvokeEvent } from 'electron';
 
 import { DataCache } from '../services';
-import { stripSessionDetailMessages } from '../services/analysis/sessionDetailPayload';
 import {
   type ConversationGroup,
   type PaginatedSessionsResult,
@@ -248,12 +247,8 @@ async function handleGetSessionDetail(
     );
     session.hasSubagents = subagents.length > 0;
 
-    // Build session detail with chunks. Strip the raw `messages` array before
-    // caching/returning — the renderer only consumes chunks/processes/session,
-    // and including messages doubled IPC payload size and cache footprint.
-    sessionDetail = stripSessionDetailMessages(
-      chunkBuilder.buildSessionDetail(session, parsedSession.messages, subagents)
-    );
+    // Build session detail with chunks
+    sessionDetail = chunkBuilder.buildSessionDetail(session, parsedSession.messages, subagents);
 
     // Cache the result
     dataCache.set(cacheKey, sessionDetail);

src/main/services/analysis/sessionDetailPayload.ts

@@ -1,24 +0,0 @@
-import type { SessionDetail } from '../../types';
-
-/**
- * Strip the raw `messages` array from a `SessionDetail` before it crosses the
- * IPC / HTTP boundary to the renderer.
- *
- * The renderer consumes `session`, `chunks`, `processes`, and `metrics` only —
- * `messages` is an implementation detail that `ChunkBuilder` retains for
- * internal callers. Including it in the serialized payload roughly doubled
- * the IPC cost for sessions with large JSONL files (tens of MB per response)
- * while also inflating the in-memory `DataCache` footprint. The field is
- * preserved (as an empty array) so the shared `SessionDetail` type stays
- * satisfied and downstream code can still observe `.messages.length === 0`
- * without runtime type narrowing.
- */
-export function stripSessionDetailMessages(detail: SessionDetail): SessionDetail {
-  if (detail.messages.length === 0) {
-    return detail;
-  }
-  return {
-    ...detail,
-    messages: [],
-  };
-}

src/shared/constants/cache.ts

@@ -2,15 +2,8 @@
  * Cache-related constants.
  */
 
-/**
- * Maximum number of session details retained in the in-memory LRU cache.
- *
- * Users regularly juggle dozens of sessions — the previous cap of 5 caused
- * constant re-parsing of large JSONL files on every session switch. Raised
- * now that the per-entry footprint is bounded (the raw `messages` array is
- * stripped before caching; see `stripSessionDetailMessages`).
- */
-export const MAX_CACHE_SESSIONS = 20;
+/** Maximum number of sessions to cache */
+export const MAX_CACHE_SESSIONS = 5;
 
 /** Cache TTL in minutes */
 export const CACHE_TTL_MINUTES = 5;

test/main/services/analysis/sessionDetailPayload.test.ts

@@ -1,68 +0,0 @@
-import { describe, expect, it } from 'vitest';
-
-import { stripSessionDetailMessages } from '../../../../src/main/services/analysis/sessionDetailPayload';
-import type { ParsedMessage, SessionDetail } from '../../../../src/main/types';
-
-function createDetail(overrides: Partial<SessionDetail> = {}): SessionDetail {
-  return {
-    session: {
-      id: 'session-1',
-      projectId: 'project-1',
-      projectPath: '/tmp/project',
-      isOngoing: false,
-      hasSubagents: false,
-      messageCount: 0,
-      createdAt: 0,
-    },
-    messages: [],
-    chunks: [],
-    processes: [],
-    metrics: {
-      durationMs: 0,
-      totalTokens: 0,
-      inputTokens: 0,
-      outputTokens: 0,
-      cacheReadTokens: 0,
-      cacheCreationTokens: 0,
-      messageCount: 0,
-    },
-    ...overrides,
-  };
-}
-
-describe('stripSessionDetailMessages', () => {
-  it('returns the same reference when messages is already empty', () => {
-    const detail = createDetail();
-    const result = stripSessionDetailMessages(detail);
-    expect(result).toBe(detail);
-  });
-
-  it('drops the messages array when it is non-empty', () => {
-    const messages = [{ uuid: 'm-1' } as unknown as ParsedMessage];
-    const detail = createDetail({ messages });
-    const result = stripSessionDetailMessages(detail);
-    expect(result).not.toBe(detail);
-    expect(result.messages).toEqual([]);
-  });
-
-  it('preserves every other field (session, chunks, processes, metrics)', () => {
-    const messages = Array.from(
-      { length: 3 },
-      (_, i) => ({ uuid: `m-${i}` }) as unknown as ParsedMessage
-    );
-    const detail = createDetail({ messages });
-    const result = stripSessionDetailMessages(detail);
-    expect(result.session).toBe(detail.session);
-    expect(result.chunks).toBe(detail.chunks);
-    expect(result.processes).toBe(detail.processes);
-    expect(result.metrics).toBe(detail.metrics);
-  });
-
-  it('does not mutate the input detail', () => {
-    const messages = [{ uuid: 'm-1' } as unknown as ParsedMessage];
-    const detail = createDetail({ messages });
-    stripSessionDetailMessages(detail);
-    expect(detail.messages).toBe(messages);
-    expect(detail.messages).toHaveLength(1);
-  });
-});