fix(web): usable past-conversation list, and search that finds past sessions

Two home-screen reports from @jordan8037310, both about history that is
present but unreachable.

#260 — "Resume Conversation" rendered 4 rows, then a button that appended
every remaining row into a `max-height: 240px` box, so 35 conversations
landed in a four-row scroll well with no ordering or filtering. Rendering
now goes through `_renderHistoryList()` over a cached corpus: 10 rows to
start, Show more/Show less that grows and shrinks the box (the height cap
is class-driven, `.history-list.expanded`), plus a filter box (name,
folder, #case label, prompts), a sort control (recent / name / folder,
pinned rows still first) and a shown-of-total count. A filter implies
expansion, so every match is visible, and the whole header hides as one
unit while a federated search is active. The A-Z sort keys off the same
string the row renders, since most rows are transcript-backed and carry
no session name at all.

#261 — the search box could not match a past project by folder name:
`harvestSources()` built its session corpus from the live in-memory map,
while past sessions come from `/api/sessions/unified` (lifecycle log +
transcript scan). Folding that scan into the request path would have cost
the search its no-filesystem-reads property, so the corpus arrives via a
bounded snapshot instead: `session-history-index.ts` is published as a
side effect of `/api/sessions/unified` (the home screen fetches it on
open, which is the same screen the search box lives on) and rebuilt
fire-and-forget, single-flight and TTL-guarded when a search finds it
stale. A result for a closed session now resumes the conversation rather
than selecting a tab that no longer exists, and is badged RESUME.

The snapshot is stored unscoped with a per-row owner and re-filtered
through canAccessOwned() on read, so multi-user sees exactly what
/api/sessions/unified exposes: own sessions only, host-wide transcript
history admin-only. Live rows are harvested first and win the dedupe.

Verified end-to-end against a real instance with 60 past sessions: cold
process answers its first search without history and its second with it;
folder-name queries return resume targets; clicking one posts the right
resumeSessionId + workingDir.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/search-service.ts

@@ -36,13 +36,21 @@ export const SEARCH_PER_GROUP_CAP = 25;
 /** Maximum characters in a result snippet. */
 export const SEARCH_SNIPPET_MAX = 200;
 
-/** A live-session row harvested for the session/case source. */
+/** A session row harvested for the session/case source (live or past). */
 export interface SessionSearchInput {
   sessionId: string;
   sessionName: string;
   workingDir: string;
   /** Recency timestamp (e.g. lastActivityAt or createdAt). */
   timestamp: number;
+  /**
+   * True for a session that is no longer running (issue #261 — past sessions come
+   * from the history index, not the live map). Such a result resumes the
+   * conversation instead of switching to a tab that no longer exists.
+   */
+  history?: boolean;
+  /** Claude conversation UUID to resume, when it differs from the Codeman id. */
+  claudeSessionId?: string;
 }
 
 /** A run-summary timeline event harvested for the event source. */
@@ -121,14 +129,25 @@ export function searchSources(query: string, sources: SearchSources): SearchResp
   const sessionRows: SearchResult[] = [];
   for (const s of sources.sessions) {
     if (contains(s.sessionName) || contains(s.workingDir) || contains(s.sessionId)) {
+      const label = s.sessionName || s.workingDir.split('/').pop() || s.sessionId;
       sessionRows.push({
         type: 'session',
         sessionId: s.sessionId,
-        sessionName: s.sessionName,
+        sessionName: label,
         timestamp: s.timestamp,
-        snippet: truncate(s.workingDir ? `${s.sessionName} — ${s.workingDir}` : s.sessionName),
+        snippet: truncate(s.workingDir ? `${label} — ${s.workingDir}` : label),
         exactMatch: isExact(s.sessionName),
-        jumpTo: { kind: 'session', sessionId: s.sessionId },
+        // A resume needs a directory to run in, so a history row without one
+        // stays a plain session target rather than an action that cannot work.
+        jumpTo:
+          s.history && s.workingDir
+            ? {
+                kind: 'resume-session',
+                sessionId: s.sessionId,
+                claudeSessionId: s.claudeSessionId,
+                workingDir: s.workingDir,
+              }
+            : { kind: 'session', sessionId: s.sessionId },
       });
     }
   }

src/types/search.ts

@@ -22,15 +22,19 @@ export type SearchSourceType = 'session' | 'event' | 'file';
 
 /** Where the frontend should jump when a result card is activated. */
 export interface SearchJumpTarget {
-  /** Kind of navigation target. */
-  kind: 'session' | 'run-summary' | 'file-preview';
+  /**
+   * Kind of navigation target. `resume-session` marks a session that is no longer
+   * running: selecting it has to REPLAY the conversation rather than switch to a
+   * tab that does not exist.
+   */
+  kind: 'session' | 'run-summary' | 'file-preview' | 'resume-session';
   /** Owning Codeman session id (always present — every result is session-scoped). */
   sessionId: string;
   /**
    * Secondary identifier for the target:
    * - kind 'run-summary': the run-summary event id
    * - kind 'file-preview': the attachment history item id
-   * - kind 'session': undefined (the sessionId is sufficient)
+   * - kind 'session' / 'resume-session': undefined (the sessionId is sufficient)
    */
   targetId?: string;
   /**
@@ -38,6 +42,16 @@ export interface SearchJumpTarget {
    * server-private external paths are intentionally omitted to avoid leakage.
    */
   relativePath?: string;
+  /**
+   * `resume-session` only: the Claude conversation UUID to resume, when it differs
+   * from the Codeman session id (resumed and `/clear`-respawned sessions).
+   */
+  claudeSessionId?: string;
+  /**
+   * `resume-session` only: the directory to resume in. Already visible in the
+   * result snippet for session rows, so this exposes nothing new.
+   */
+  workingDir?: string;
 }
 
 /** A single typed search result card. */

src/web/public/index.html

@@ -397,7 +397,27 @@
               </div>
               <div class="search-results" id="searchResults" hidden></div>
             </div>
-            <h3 class="history-title" id="historyTitle">Resume Conversation</h3>
+            <div class="history-header" id="historyHeader">
+              <h3 class="history-title" id="historyTitle">Resume Conversation</h3>
+              <span class="history-count" id="historyCount" data-i18n-skip></span>
+              <div class="history-controls">
+                <input
+                  type="search"
+                  id="historyFilter"
+                  class="history-filter"
+                  placeholder="Filter…"
+                  autocomplete="off"
+                  spellcheck="false"
+                  maxlength="100"
+                  aria-label="Filter past conversations"
+                />
+                <select id="historySort" class="search-select history-sort" aria-label="Sort past conversations">
+                  <option value="recent">Recent</option>
+                  <option value="name">Name A–Z</option>
+                  <option value="folder">Folder A–Z</option>
+                </select>
+              </div>
+            </div>
             <div class="history-list" id="historyList"></div>
           </div>
           <p class="welcome-hint">Or click Run to start</p>

src/web/public/styles.css

@@ -3666,6 +3666,13 @@ body.touch-device .terminal-container .xterm .xterm-helper-textarea {
   color: #95e6b3;
 }
 
+/* Past session (issue #261): activating the card resumes the conversation
+   rather than switching to a tab, so the badge says so. */
+.search-badge-past {
+  background: rgba(245, 158, 11, 0.18);
+  color: #f0c073;
+}
+
 .search-result-name {
   flex: 1;
   min-width: 0;
@@ -3715,24 +3722,99 @@ body.touch-device .terminal-container .xterm .xterm-helper-textarea {
   .search-select {
     max-width: 7rem;
   }
+  /* Tablet/narrow: let the controls drop under the title instead of squeezing it. */
+  .history-header {
+    flex-wrap: wrap;
+  }
+  .history-controls {
+    width: 100%;
+    margin-left: 0;
+  }
+  .history-filter {
+    flex: 1;
+    width: auto;
+  }
+}
+
+/* Title row for the past-session list: label + count on the left, filter and
+   sort on the right (issue #260 — 35 conversations in a 4-row box). */
+.history-header {
+  display: flex;
+  align-items: center;
+  gap: 0.5rem;
+  margin-bottom: 0.5rem;
 }
 
 .history-title {
   font-size: 0.85rem;
   color: var(--text-dim);
-  margin-bottom: 0.5rem;
   font-weight: 500;
   text-align: left;
 }
 
+.history-count {
+  font-size: 0.68rem;
+  color: var(--text-dim);
+  background: rgba(255, 255, 255, 0.05);
+  border-radius: 999px;
+  padding: 0.1rem 0.45rem;
+  white-space: nowrap;
+}
+
+.history-controls {
+  display: flex;
+  align-items: center;
+  gap: 0.35rem;
+  margin-left: auto;
+}
+
+.history-filter {
+  width: 8.5rem;
+  box-sizing: border-box;
+  padding: 0.28rem 0.5rem;
+  font-size: 0.68rem;
+  color: var(--text);
+  background: rgba(255, 255, 255, 0.03);
+  border: 1px solid rgba(255, 255, 255, 0.1);
+  border-radius: 6px;
+  outline: none;
+  transition: border-color var(--transition-smooth), background var(--transition-smooth);
+}
+
+.history-filter:focus {
+  border-color: rgba(59, 130, 246, 0.5);
+  background: rgba(255, 255, 255, 0.06);
+}
+
+.history-filter::placeholder {
+  color: var(--text-dim);
+}
+
+.history-sort {
+  max-width: 7.5rem;
+}
+
+.history-empty {
+  padding: 0.75rem 0.5rem;
+  font-size: 0.75rem;
+  color: var(--text-dim);
+  text-align: center;
+}
+
+/* Collapsed height fits the initial page of rows; expanding the LIST has to
+   expand the BOX too, or "Show more" just deepens a scroll well. */
 .history-list {
   display: flex;
   flex-direction: column;
   gap: 0.35rem;
-  max-height: 240px;
+  max-height: min(42vh, 360px);
   overflow-y: auto;
 }
 
+.history-list.expanded {
+  max-height: min(64vh, 660px);
+}
+
 .history-item {
   display: flex;
   flex-direction: column;

src/web/public/terminal-ui.js

@@ -1628,7 +1628,7 @@ Object.assign(CodemanApp.prototype, {
       pin.title = 'Pinned';
       titleSpan.appendChild(pin);
     }
-    titleSpan.appendChild(document.createTextNode(s.name || s.firstPrompt || shortDir));
+    titleSpan.appendChild(document.createTextNode(this._historyRowLabel(s, shortDir)));
 
     // Badge row: mode (claude/codex/opencode/gemini/antigravity/shell) + a LIVE pill.
     const badgeRow = document.createElement('div');
@@ -1954,7 +1954,10 @@ Object.assign(CodemanApp.prototype, {
   },
 
   /** Number of history items shown before "Show More" */
-  _HISTORY_INITIAL_COUNT: 4,
+  _HISTORY_INITIAL_COUNT: 10,
+
+  /** How many past sessions the home screen loads (also the filter/sort corpus). */
+  _HISTORY_FETCH_LIMIT: 60,
 
   async loadHistorySessions() {
     const container = document.getElementById('historySessions');
@@ -1968,7 +1971,7 @@ Object.assign(CodemanApp.prototype, {
         ? Promise.resolve(this.cases)
         : fetch('/api/cases').then((r) => (r.ok ? r.json() : null)).then((d) => d?.data || []).catch(() => []);
       const [allSessions, cases] = await Promise.all([
-        this._fetchUnifiedSessions(60),
+        this._fetchUnifiedSessions(this._HISTORY_FETCH_LIMIT),
         casesPromise,
       ]);
       if (allSessions.length === 0) {
@@ -1976,27 +1979,14 @@ Object.assign(CodemanApp.prototype, {
         return;
       }
 
-      list.replaceChildren();
-      const initialCount = this._HISTORY_INITIAL_COUNT;
-
-      // Render initial items
-      for (let i = 0; i < Math.min(initialCount, allSessions.length); i++) {
-        list.appendChild(this._buildHistoryItem(allSessions[i], cases));
-      }
-
-      // Add "Show More" button if there are more items
-      if (allSessions.length > initialCount) {
-        const moreBtn = document.createElement('button');
-        moreBtn.className = 'history-show-more';
-        moreBtn.textContent = `Show ${allSessions.length - initialCount} more`;
-        moreBtn.addEventListener('click', () => {
-          for (let i = initialCount; i < allSessions.length; i++) {
-            list.insertBefore(this._buildHistoryItem(allSessions[i], cases), moreBtn);
-          }
-          moreBtn.remove();
-        });
-        list.appendChild(moreBtn);
-      }
+      // Keep the corpus around: filtering and sorting (issue #260) work on this
+      // array, so a re-render costs no request. Expansion survives the periodic
+      // refresh in panels-ui.js — collapsing the list under the user's cursor
+      // every few seconds would be worse than the original 4-item cap.
+      this._historyAll = allSessions;
+      this._historyCases = cases;
+      this._wireHistoryControls();
+      this._renderHistoryList();
 
       container.style.display = '';
     } catch (err) {
@@ -2005,6 +1995,131 @@ Object.assign(CodemanApp.prototype, {
     }
   },
 
+  /** Wire the filter box and sort select once; both re-render from the cached corpus. */
+  _wireHistoryControls() {
+    if (this._historyControlsWired) return;
+    const filter = document.getElementById('historyFilter');
+    const sort = document.getElementById('historySort');
+    if (!filter && !sort) return;
+    this._historyControlsWired = true;
+
+    if (filter) {
+      filter.addEventListener('input', () => this._renderHistoryList());
+      filter.addEventListener('keydown', (ev) => {
+        if (ev.key === 'Escape' && filter.value) {
+          // Swallow it: Escape at the welcome screen otherwise closes overlays.
+          ev.stopPropagation();
+          filter.value = '';
+          this._renderHistoryList();
+        }
+      });
+    }
+    if (sort) sort.addEventListener('change', () => this._renderHistoryList());
+  },
+
+  /** True when a past-session row matches the filter text (name, folder, case, prompt). */
+  _historyRowMatches(s, needle, cases) {
+    const fields = [
+      s.name,
+      s.workingDir,
+      this._resolveCaseLabel(s.workingDir, cases),
+      s.firstPrompt,
+      s.lastPrompt,
+      s.sessionId,
+    ];
+    return fields.some((f) => typeof f === 'string' && f.toLowerCase().includes(needle));
+  },
+
+  /**
+   * The text a history row shows as its title. Most transcript-backed rows have
+   * no session name at all, so this falls through to the first prompt and then
+   * to the path — and the A–Z sort keys off the SAME string, or "sort by name"
+   * would silently do nothing for exactly the rows the list is mostly made of.
+   */
+  _historyRowLabel(s, fallback) {
+    return s.name || s.firstPrompt || fallback || '';
+  },
+
+  /**
+   * Sort past-session rows. 'recent' keeps the backend order (newest first);
+   * the alphabetical modes sort by the visible title or by folder basename.
+   * Pinned rows stay on top in every mode — pinning is an explicit override and
+   * a sort that buried it would read as the pin having been lost.
+   */
+  _sortHistoryRows(rows, mode) {
+    const label = (s) => this._historyRowLabel(s, this._shortenHomePath(s.workingDir)).toLowerCase();
+    const folder = (s) => ((s.workingDir || '').split('/').pop() || '').toLowerCase();
+    const key = mode === 'name' ? label : folder;
+    const sorted = mode === 'recent' ? rows.slice() : rows.slice().sort((a, b) => key(a).localeCompare(key(b)));
+    const pinned = sorted.filter((s) => s.pinned);
+    return pinned.length === 0 ? sorted : pinned.concat(sorted.filter((s) => !s.pinned));
+  },
+
+  /**
+   * Render the "Resume Conversation" list from the cached corpus, applying the
+   * current filter and sort. Collapsed by default to _HISTORY_INITIAL_COUNT;
+   * "Show more" expands the list AND the box (the CSS cap is class-driven, since
+   * a fixed 240px box made expansion pointless — issue #260).
+   */
+  _renderHistoryList() {
+    const list = document.getElementById('historyList');
+    if (!list) return;
+    const all = this._historyAll || [];
+    const cases = this._historyCases || [];
+    const countEl = document.getElementById('historyCount');
+    const needle = (document.getElementById('historyFilter')?.value || '').trim().toLowerCase();
+    const mode = document.getElementById('historySort')?.value || 'recent';
+
+    const matched = needle ? all.filter((s) => this._historyRowMatches(s, needle, cases)) : all;
+    const rows = this._sortHistoryRows(matched, mode);
+    // Filtering is itself an expansion request: hiding matches behind "Show more"
+    // would defeat the point of typing a filter.
+    const expanded = !!this._historyExpanded || needle.length > 0;
+    const visible = expanded ? rows : rows.slice(0, this._HISTORY_INITIAL_COUNT);
+
+    list.replaceChildren();
+    list.classList.toggle('expanded', expanded);
+
+    if (rows.length === 0) {
+      const empty = document.createElement('div');
+      empty.className = 'history-empty';
+      empty.textContent = `No conversations match "${needle}"`;
+      list.appendChild(empty);
+    }
+
+    for (const s of visible) list.appendChild(this._buildHistoryItem(s, cases));
+
+    const hidden = rows.length - visible.length;
+    if (hidden > 0) {
+      const moreBtn = document.createElement('button');
+      moreBtn.className = 'history-show-more';
+      moreBtn.textContent = `Show ${hidden} more`;
+      moreBtn.addEventListener('click', () => {
+        this._historyExpanded = true;
+        this._renderHistoryList();
+      });
+      list.appendChild(moreBtn);
+    } else if (expanded && !needle && rows.length > this._HISTORY_INITIAL_COUNT) {
+      const lessBtn = document.createElement('button');
+      lessBtn.className = 'history-show-more';
+      lessBtn.textContent = 'Show less';
+      lessBtn.addEventListener('click', () => {
+        this._historyExpanded = false;
+        this._renderHistoryList();
+        list.scrollTop = 0;
+      });
+      list.appendChild(lessBtn);
+    }
+
+    if (countEl) {
+      countEl.textContent = needle
+        ? `${rows.length} of ${all.length}`
+        : rows.length > visible.length
+          ? `${visible.length} of ${rows.length}`
+          : String(rows.length);
+    }
+  },
+
   /** Page size for the folder history modal */
   _FOLDER_HISTORY_PAGE_SIZE: 20,
 
@@ -3832,13 +3947,16 @@ Object.assign(CodemanApp.prototype, {
   /** Render the grouped result cards (or empty/loading states). */
   _renderSearch(data) {
     const results = document.getElementById('searchResults');
-    const historyTitle = document.getElementById('historyTitle');
+    // The header carries the title plus the filter/sort controls (issue #260) —
+    // hide the whole row, not just the title, or the controls float above the
+    // search results and act on a list that is not on screen.
+    const historyHeader = document.getElementById('historyHeader') || document.getElementById('historyTitle');
     const historyList = document.getElementById('historyList');
     if (!results) return;
 
     const searching = !!data;
     // Hide the plain "Resume Conversation" history list while a search is active.
-    if (historyTitle) historyTitle.style.display = searching ? 'none' : '';
+    if (historyHeader) historyHeader.style.display = searching ? 'none' : '';
     if (historyList) historyList.style.display = searching ? 'none' : '';
 
     results.innerHTML = '';
@@ -3907,9 +4025,11 @@ Object.assign(CodemanApp.prototype, {
     const topRow = document.createElement('div');
     topRow.className = 'search-result-top';
 
+    // A past session resumes rather than switches tabs, so it says so on the badge.
+    const isPast = r.jumpTo && r.jumpTo.kind === 'resume-session';
     const badge = document.createElement('span');
-    badge.className = 'search-result-badge search-badge-' + r.type;
-    badge.textContent = (window.CodemanSearch.SOURCE_LABELS[r.type] || r.type).replace(/s$/, '');
+    badge.className = 'search-result-badge search-badge-' + r.type + (isPast ? ' search-badge-past' : '');
+    badge.textContent = isPast ? 'Resume' : (window.CodemanSearch.SOURCE_LABELS[r.type] || r.type).replace(/s$/, '');
 
     const name = document.createElement('span');
     name.className = 'search-result-name';
@@ -3941,13 +4061,20 @@ Object.assign(CodemanApp.prototype, {
 
   /**
    * Navigate to a search result by jumpTo.kind, reusing the existing app methods:
-   *   session     → selectSession(sessionId)        (open/switch to the session)
-   *   run-summary → openRunSummary(sessionId)        (session options → summary tab)
-   *   file-preview→ openFilePreview(path, sessionId, attachmentId)
+   *   session       → selectSession(sessionId)      (open/switch to the session)
+   *   resume-session→ resumeHistorySession(...)     (past session — no tab to switch to)
+   *   run-summary   → openRunSummary(sessionId)     (session options → summary tab)
+   *   file-preview  → openFilePreview(path, sessionId, attachmentId)
    */
   _jumpToSearchResult(r) {
     const jt = r && r.jumpTo;
     if (!jt) return;
+    // A past session has to be replayed, not switched to. Do it BEFORE hiding the
+    // welcome overlay: resumeHistorySession() owns that transition itself.
+    if (jt.kind === 'resume-session') {
+      this.resumeHistorySession(jt.claudeSessionId || jt.sessionId, jt.workingDir || '', r.sessionName);
+      return;
+    }
     // Leaving the welcome overlay so the target surface is visible.
     if (typeof this.hideWelcome === 'function') this.hideWelcome();
 

src/web/routes/search-routes.ts

@@ -3,7 +3,9 @@
  *
  * Registers `GET /api/search?q=&types=&limit=` — a bounded, in-memory search
  * across three v1 sources, returned in the standard ApiResponse envelope:
- *   1. sessions/cases — name, working directory, session id
+ *   1. sessions/cases — name, working directory, session id, for LIVE sessions
+ *      plus the past-session snapshot in `session-history-index.ts` (issue #261:
+ *      the live map alone made every closed session unfindable by folder name)
  *   2. run-summary events — event title/details (from the live run-summary trackers)
  *   3. file paths — per-session attachment history (workspace-relative paths only)
  *
@@ -34,6 +36,7 @@ import {
 } from '../../search-service.js';
 import type { SearchSourceType } from '../../types/search.js';
 import type { SessionPort, InfraPort } from '../ports/index.js';
+import { ensureHistorySessionIndexFresh, getHistorySessionIndex } from '../session-history-index.js';
 
 /**
  * Per-source harvest caps. These bound how much in-memory data we hand to the
@@ -61,11 +64,17 @@ interface SessionLike {
 /**
  * Harvest the three source arrays from the live in-memory stores. Reads only
  * bounded, already-loaded data — no disk I/O, no terminal buffers.
+ *
+ * Past sessions come from the `session-history-index` snapshot, which is built
+ * outside the request path for exactly that reason. Live rows are harvested
+ * first and win the dedupe, so a session that is both live and in the snapshot
+ * keeps its live jump-to (switch to the tab) instead of a resume.
  */
 function harvestSources(ctx: SessionPort & InfraPort, canSee?: (owner?: string) => boolean): SearchSources {
   const sessions: SessionSearchInput[] = [];
   const events: EventSearchInput[] = [];
   const files: FileSearchInput[] = [];
+  const seenSessionIds = new Set<string>();
 
   for (const raw of ctx.sessions.values()) {
     const s = raw as unknown as SessionLike & { owner?: string };
@@ -73,6 +82,7 @@ function harvestSources(ctx: SessionPort & InfraPort, canSee?: (owner?: string)
     const sessionName = s.name ?? '';
     const timestamp = s.lastActivityAt ?? s.createdAt ?? 0;
 
+    seenSessionIds.add(s.id);
     sessions.push({
       sessionId: s.id,
       sessionName,
@@ -95,6 +105,24 @@ function harvestSources(ctx: SessionPort & InfraPort, canSee?: (owner?: string)
     }
   }
 
+  // Past sessions: the out-of-band snapshot of the unified list. Unscoped on
+  // disk, so every row goes through the same ownership check as a live one —
+  // host-wide transcript rows carry no owner and are therefore admin-only in
+  // multi-user mode, matching GET /api/sessions/unified.
+  for (const item of getHistorySessionIndex().items) {
+    if (seenSessionIds.has(item.sessionId)) continue;
+    if (canSee && !canSee(item.owner)) continue;
+    seenSessionIds.add(item.sessionId);
+    sessions.push({
+      sessionId: item.sessionId,
+      sessionName: item.name,
+      workingDir: item.workingDir,
+      timestamp: item.timestamp,
+      history: true,
+      claudeSessionId: item.claudeSessionId,
+    });
+  }
+
   // Events: from the live run-summary trackers, keyed by session id.
   for (const [sessionId, tracker] of ctx.runSummaryTrackers) {
     const session = ctx.sessions.get(sessionId) as unknown as (SessionLike & { owner?: string }) | undefined;
@@ -134,6 +162,11 @@ export function registerSearchRoutes(app: FastifyInstance, ctx: SessionPort & In
         )
       : null;
 
+    // Fire-and-forget: a stale past-session snapshot is rebuilt in the
+    // background. This query still answers from whatever is already in memory,
+    // which is what keeps the request path free of disk I/O.
+    ensureHistorySessionIndexFresh();
+
     const sources = harvestSources(ctx, canSee);
 
     // Apply the optional source-type filter before searching so excluded

src/web/routes/session-routes.ts

@@ -94,7 +94,13 @@ import {
   type LifecycleInput,
   type HistoryInput,
   type MuxStatInput,
+  type UnifiedSessionItem,
 } from '../../services/unified-session-service.js';
+import {
+  buildHistorySessionIndexItems,
+  setHistoryIndexRefresher,
+  setHistorySessionIndex,
+} from '../session-history-index.js';
 import type { SessionPort, EventPort, ConfigPort, InfraPort, AuthPort } from '../ports/index.js';
 import { RunSummaryTracker } from '../../run-summary.js';
 
@@ -3539,16 +3545,20 @@ export function registerSessionRoutes(
     return { sessions: results.slice(0, 50) };
   });
 
-  // Unified, read-only session list: merges live + persisted + lifecycle +
-  // transcript history + mux stats into one de-duplicated, searchable list
-  // (COD-121). Pure merge/filter logic lives in unified-session-service.ts.
-  app.get('/api/sessions/unified', async (req) => {
-    const query = req.query as { q?: string; offset?: string; limit?: string };
-
-    if (ctx.testMode) {
-      return { sessions: [], total: 0 };
-    }
-
+  /**
+   * Gather the four read-only views the unified list is merged from, plus mux
+   * stats. This is the expensive half (the lifecycle log and a scan of every
+   * Claude transcript), factored out of the route handler because the
+   * past-session search index rebuilds itself from the very same inputs — off
+   * the request path, see session-history-index.ts.
+   */
+  async function gatherUnifiedInputs(): Promise<{
+    live: LiveSessionInput[];
+    persisted: PersistedSessionInput[];
+    lifecycle: LifecycleInput[];
+    history: HistoryInput[];
+    mux: MuxStatInput[];
+  }> {
     // Live (in-memory) sessions.
     const live: LiveSessionInput[] = [...ctx.sessions.values()].map((s) => {
       const st = s.toState();
@@ -3649,14 +3659,54 @@ export function registerSessionRoutes(
       // Mux stats are optional.
     }
 
+    return { live, persisted, lifecycle, history, mux };
+  }
+
+  /**
+   * Publish a merged unified list as the past-session search index (issue #261).
+   * The snapshot is stored UNSCOPED with a per-row owner, so it must only ever be
+   * built from an unscoped merge — `harvestSources()` in search-routes re-applies
+   * the ownership check on read.
+   */
+  function publishHistorySessionIndex(merged: UnifiedSessionItem[]): void {
+    const ownerById = new Map<string, string | undefined>();
+    const stored = ctx.store.getState().sessions as Record<string, { id: string; owner?: string }>;
+    for (const p of Object.values(stored)) ownerById.set(p.id, p.owner);
+    // Live wins: a session's owner on disk can lag the running one.
+    for (const s of ctx.sessions.values()) ownerById.set(s.id, s.owner);
+    const liveIds = new Set(ctx.sessions.keys());
+    setHistorySessionIndex(buildHistorySessionIndexItems(merged, ownerById, liveIds));
+  }
+
+  // Rebuild hook for the search route: it kicks this (fire-and-forget) when the
+  // snapshot goes stale, so a search never pays for the scan itself.
+  setHistoryIndexRefresher(async () => {
+    if (ctx.testMode) return;
+    publishHistorySessionIndex(mergeUnifiedSessions(await gatherUnifiedInputs()));
+  });
+
+  // Unified, read-only session list: merges live + persisted + lifecycle +
+  // transcript history + mux stats into one de-duplicated, searchable list
+  // (COD-121). Pure merge/filter logic lives in unified-session-service.ts.
+  app.get('/api/sessions/unified', async (req) => {
+    const query = req.query as { q?: string; offset?: string; limit?: string };
+
+    if (ctx.testMode) {
+      return { sessions: [], total: 0 };
+    }
+
+    const { live, persisted, lifecycle, history, mux } = await gatherUnifiedInputs();
+
     // Multi-user: a non-admin only sees their own sessions; host-wide transcript
     // history (not tied to an owned session) is admin-only.
     let sLive = live;
     let sPersisted = persisted;
     let sLifecycle = lifecycle;
     let sHistory = history;
+    let scoped = false;
     const uUser = getAuthUser(req);
     if (isMultiUserMode() && uUser.role !== 'admin') {
+      scoped = true;
       const ownedLive = new Set(
         [...ctx.sessions.values()].filter((s) => canAccessOwned(uUser, s.owner)).map((s) => s.id)
       );
@@ -3680,6 +3730,14 @@ export function registerSessionRoutes(
       history: sHistory,
       mux,
     });
+
+    // Refresh the search index off the back of this request — the home screen
+    // fetches this endpoint whenever it opens, which is the same screen the
+    // search box lives on, so the snapshot is warm before anyone types. A scoped
+    // merge is a per-user subset and would corrupt the shared snapshot, so that
+    // path re-merges unscoped instead (multi-user is opt-in and rarely hit).
+    publishHistorySessionIndex(scoped ? mergeUnifiedSessions({ live, persisted, lifecycle, history, mux }) : merged);
+
     const offset = query.offset !== undefined ? parseInt(query.offset, 10) : undefined;
     const limit = query.limit !== undefined ? parseInt(query.limit, 10) : undefined;
     return filterAndPaginate(merged, {

src/web/session-history-index.ts

@@ -0,0 +1,166 @@
+/**
+ * @fileoverview Bounded in-memory index of PAST sessions, harvested by `GET /api/search`.
+ *
+ * `GET /api/search` used to build its session corpus from the live in-memory
+ * session map alone, so a folder sitting in the home screen's "Resume
+ * Conversation" list matched nothing (issue #261). The corpus that list renders
+ * comes from `GET /api/sessions/unified`, which reads the lifecycle log and every
+ * Claude transcript file — disk I/O the search path deliberately does not do
+ * (its no-fs property is what keeps a per-keystroke query cheap and traversal-free).
+ *
+ * This module is the seam between the two: a capped snapshot of the unified list
+ * that the search route reads synchronously, refreshed OUT of the request path.
+ * Two things fill it:
+ *   1. `/api/sessions/unified` writes it as a side effect (free — it just merged
+ *      that list). The home screen calls that endpoint whenever it opens, which
+ *      is the same screen the search box lives on, so it is warm in practice.
+ *   2. `ensureHistorySessionIndexFresh()` — fire-and-forget, single-flight,
+ *      TTL-guarded — kicks the registered refresher when a search finds the
+ *      snapshot stale. The caller never awaits it: the current query answers from
+ *      the existing snapshot and the next one sees fresh data.
+ *
+ * OWNERSHIP: each item carries the `owner` of the session it came from, and rows
+ * not tied to any live/persisted session (host-wide transcript history) carry
+ * `owner: undefined`. `canAccessOwned()` then reproduces the unified route's rule
+ * exactly — in multi-user mode a non-admin sees neither other users' sessions nor
+ * unowned host-wide history, and in single-user mode every check short-circuits
+ * true. The snapshot is written UNSCOPED, so it must never be returned unfiltered.
+ *
+ * Key exports:
+ * - setHistorySessionIndex / getHistorySessionIndex — the snapshot accessors.
+ * - buildHistorySessionIndexItems — pure merged-list → index-item projection.
+ * - setHistoryIndexRefresher / ensureHistorySessionIndexFresh — the refresh hook.
+ */
+
+/** One past-session row in the snapshot. Mirrors what the search corpus needs, nothing more. */
+export interface HistorySessionIndexItem {
+  /** Codeman session id (the search result's session id and dedupe key). */
+  sessionId: string;
+  /** Display name, may be empty for a transcript-only row. */
+  name: string;
+  /** Absolute working directory — the field issue #261 is about matching. */
+  workingDir: string;
+  /** Claude conversation UUID, when known: what a resume actually replays. */
+  claudeSessionId?: string;
+  /** Recency timestamp (lastActivityAt, else createdAt). */
+  timestamp: number;
+  /**
+   * Owning user, when the row is tied to a live or persisted session. `undefined`
+   * means host-wide transcript history, which only admins (or single-user mode)
+   * may see — the same rule `/api/sessions/unified` applies.
+   */
+  owner?: string;
+  /** True when the session is still in the live map (search harvests those directly). */
+  live: boolean;
+}
+
+/** Hard cap on snapshot size, so a host with thousands of transcripts stays bounded. */
+export const HISTORY_INDEX_MAX_ITEMS = 400;
+
+/** How long a snapshot is considered fresh before a search triggers a background refresh. */
+export const HISTORY_INDEX_TTL_MS = 60_000;
+
+interface HistorySessionIndexSnapshot {
+  items: HistorySessionIndexItem[];
+  /** Epoch ms of the last write; 0 when never populated. */
+  updatedAt: number;
+}
+
+let snapshot: HistorySessionIndexSnapshot = { items: [], updatedAt: 0 };
+let refresher: (() => Promise<void>) | null = null;
+let refreshInFlight = false;
+
+/** The merged-list shape this module projects from (a subset of `UnifiedSessionItem`). */
+export interface MergedSessionLike {
+  sessionId: string;
+  name?: string;
+  workingDir?: string;
+  claudeSessionId?: string;
+  createdAt?: number;
+  lastActivityAt?: number;
+}
+
+/**
+ * Project a merged unified list into index items. PURE — the caller supplies the
+ * owner lookup and the live-id set it already has in hand.
+ *
+ * Rows with no working directory AND no name are dropped: they can never match a
+ * query in a useful way and would only consume the cap.
+ *
+ * @param merged unified-list items, newest-first (the order the merge returns)
+ * @param ownerById owner of a session id, for rows tied to a live/persisted session
+ * @param liveIds session ids currently in the live map
+ */
+export function buildHistorySessionIndexItems(
+  merged: MergedSessionLike[],
+  ownerById: Map<string, string | undefined>,
+  liveIds: Set<string>
+): HistorySessionIndexItem[] {
+  const items: HistorySessionIndexItem[] = [];
+  for (const m of merged) {
+    if (items.length >= HISTORY_INDEX_MAX_ITEMS) break;
+    const name = m.name ?? '';
+    const workingDir = m.workingDir ?? '';
+    if (!name && !workingDir) continue;
+    items.push({
+      sessionId: m.sessionId,
+      name,
+      workingDir,
+      claudeSessionId: m.claudeSessionId,
+      timestamp: m.lastActivityAt ?? m.createdAt ?? 0,
+      owner: ownerById.get(m.sessionId),
+      live: liveIds.has(m.sessionId),
+    });
+  }
+  return items;
+}
+
+/** Replace the snapshot. Items are capped defensively even if the caller already did. */
+export function setHistorySessionIndex(items: HistorySessionIndexItem[], now = Date.now()): void {
+  snapshot = { items: items.slice(0, HISTORY_INDEX_MAX_ITEMS), updatedAt: now };
+}
+
+/**
+ * Read the snapshot. The returned array is UNSCOPED — callers must apply the
+ * per-item ownership check before exposing any of it.
+ */
+export function getHistorySessionIndex(): HistorySessionIndexSnapshot {
+  return snapshot;
+}
+
+/** True when the snapshot has never been written, or is older than the TTL. */
+export function isHistorySessionIndexStale(now = Date.now(), ttlMs = HISTORY_INDEX_TTL_MS): boolean {
+  return snapshot.updatedAt === 0 || now - snapshot.updatedAt > ttlMs;
+}
+
+/**
+ * Register the rebuild function. Called once by the session routes, which own the
+ * transcript scanner and the stores the unified list is merged from.
+ */
+export function setHistoryIndexRefresher(fn: (() => Promise<void>) | null): void {
+  refresher = fn;
+}
+
+/**
+ * Kick a background rebuild if the snapshot is stale. Returns immediately —
+ * NEVER await this from a request handler, that is the whole point: the search
+ * path answers from the current snapshot and stays free of disk I/O.
+ */
+export function ensureHistorySessionIndexFresh(now = Date.now()): void {
+  if (refreshInFlight || !refresher || !isHistorySessionIndexStale(now)) return;
+  refreshInFlight = true;
+  void refresher()
+    .catch(() => {
+      // A failed rebuild leaves the previous snapshot in place; the next search retries.
+    })
+    .finally(() => {
+      refreshInFlight = false;
+    });
+}
+
+/** Test hook: drop the snapshot and any registered refresher. */
+export function resetHistorySessionIndex(): void {
+  snapshot = { items: [], updatedAt: 0 };
+  refresher = null;
+  refreshInFlight = false;
+}