Compare view, session history, and snapshot/UX upgrades

CHANGELOG.md

@@ -51,8 +51,48 @@ are visible until you actually open a second tab.
   button (cloud models first, `cloud`/`local` badges, current one preselected) instead of a
   full-screen modal. It opens instantly with a loading spinner while the model list is fetched, and
   shows connection/empty-list errors inline. The typed `/model` command still uses the overlay wizard.
+- **History panel — reopen a closed conversation.** A new rail icon (with a count badge) opens a
+  docked panel, sharing the Snapshots column, that lists every conversation you've closed — title,
+  project, model, when, turn count, and the first thing you said. **Open** brings one back as a
+  fresh tab through the existing restore cascade: the transcript replays and, when the model can
+  take it, the full memory rehydrates. **Delete** forgets one for good. Search filters by title,
+  project, model, or that first message. The archive is app-wide, persisted, and capped at the
+  newest 60 — evicting an old row deletes its journals so the on-disk stores stay bounded.
+- **Snapshots panel — grouping, search, and a cleaner import.** Snapshot cards now group by the
+  project they were taken in (freshest project first), a search box filters by title/recap/model/
+  project, and Import closes the panel and focuses the chat so the "context armed" confirmation is
+  the thing you see.
+- **Collapsible project groups, in both panels.** Each project group in Snapshots and History is an
+  `Expander` you can fold — the answer to "10–100 projects." Which groups you've collapsed is
+  remembered across launches (`PanelState` → `panel-state.json`).
+- **Compare view — two agents side by side.** A **Split** button pairs two agents into a resizable
+  side-by-side view. The pair is an explicit, remembered choice (set by the button or the compare
+  bar's pickers, never by clicking a tab): clicking a paired agent's tab shows the split, clicking
+  any other agent shows it normally while the pair waits. The panes are ordinary agent views moved
+  between grid columns via `Grid.SetColumn` — never re-parented — so both WebViews and their live
+  transcripts survive the switch.
+- **AI-named snapshots.** Saving a snapshot without a name now asks the summarizer for a short,
+  descriptive title from the recap; uniqueness against existing titles is then guaranteed in code
+  (`SnapshotNaming`), so two snapshots can't share a name.
+- **Unread badges.** The History and Snapshots rail badges are now unread counts — items newer than
+  the last time you opened that panel — and clear when you open it, rather than showing a running
+  total. The "last seen" marks persist across launches.
+- **Branded app icon** across the exe, taskbar, and window title bar, plus a lightweight
+  unhandled-exception logger (`crash.log`) to speed up diagnosing native/COM failures.
 
 ### Changed
+- **Closing the last agent is allowed.** The app no longer forces at least one agent open — closing
+  the final one leaves an empty state (with the chat background) and a one-click New agent. Settings,
+  MCP, and snapshot Import disable while no agent is open and re-enable when one exists.
+- **"Take snapshot" goes straight to the picker.** The manual capture (tab `⋯` menu) skips the
+  "snapshot available?" notification bar and opens the name + summarizer-model picker directly — a
+  model switch keeps the bar, since snapshotting isn't a foregone conclusion there.
+- **Closing a tab archives it; `/clear` still forgets.** Closing used to delete a conversation's
+  journals outright ("closed tab = conversation gone"). Now it files the conversation into the
+  History archive instead, so it can be reopened later; only `/clear` (and eviction past the
+  archive cap) deletes the files. A session that never had a real turn is still dropped on close —
+  there's nothing to reopen. "Cleared means cleared" is unchanged; only *closing* softens from
+  "gone" to "recoverable."
 - **`/model` is an agent-local switch** and no longer writes to disk; the model button in each
   agent's header opens the same picker. `/setup` and the Settings page still set the app-wide
   default, because they configure the app rather than one agent.
@@ -131,8 +171,9 @@ are visible until you actually open a second tab.
   added at the next submodule pin roll; the existing side-channels either fire tools
   (`ExecutePlanStepAsync`) or would corrupt the live conversation. The panel is already built, so
   it's a button plus one method once the seam lands.
-- **Snapshots are session-scoped**, in memory only — they vanish on app close. Persisting them to
-  disk is a possible follow-up (it would need a store to name and garbage-collect).
+- **Summarize-at-restore.** The tail-brief restore fallback still excerpts the stored dialogue
+  verbatim rather than running `HistorySummarizer` over it — better coverage of long sessions is a
+  follow-up, at the cost of one LLM call on restore.
 
 ## [0.1.0] — 2026-07-07
 

README.md

@@ -80,13 +80,26 @@ graph; `SessionManager` owns the set of them. The split matters:
 | `AIService` (its conversation, its model), `ChatController`, `TaskPlannerService` | The `MandoCodeConfig` on disk — the **defaults** a new agent starts on |
 | `MandoCodeConfig` clone, `ProjectRootAccessor`, `SkillLoader`, `FileAutocompleteProvider` | `McpClientManager` (one set of server processes) |
 | `TokenTrackingService`, `PlanHandoff`, `TranscriptWriter`, `BusyStateService`, `ShellRunner` | `MusicPlayerService`, `ThemeManager`, `TranscriptHtmlBuilder` |
-| `WinUiApprovalService`, `ApprovalPromptGate`, `McpApprovalGate` | `ConfigCoordinator`, `McpCoordinator`, `SessionManager`, `SnapshotStore` |
+| `WinUiApprovalService`, `ApprovalPromptGate`, `McpApprovalGate` | `ConfigCoordinator`, `McpCoordinator`, `SessionManager`, `SnapshotStore`, `SessionArchiveStore` |
 
 Tabs default to `Agent 1`, `Agent 2`, … (the folder shows in the header); the number reuses the
 lowest free slot, and a rename or folder change never overwrites it. Each tab's `⋯` options menu
-carries Rename, Take snapshot, Export transcript, and Close — Close is greyed on the last remaining
-agent (Settings and MCP need one to act on). The model in each header opens a quick-switch dropdown
-(cloud first, `cloud`/`local` badges) rather than a full-screen picker.
+carries Rename, Take snapshot, Export transcript, and Close. The model in each header opens a
+quick-switch dropdown (cloud first, `cloud`/`local` badges) rather than a full-screen picker.
+
+Closing the **last** agent is allowed: it leaves a clean empty state (showing the chat background)
+with a one-click way to start a new agent. Actions that need an agent to act on — the Settings and
+MCP pages, and snapshot Import — disable while none is open, then re-enable when you open one.
+
+### Compare view (two agents side by side)
+
+The **Split** button pairs two agents into a resizable side-by-side view for comparing what each is
+producing. The pair is an explicit, remembered choice — set only by the Split button and the
+compare-bar pickers, never by clicking a tab. Clicking a paired agent's tab shows the split;
+clicking any other agent shows it normally while the pair waits. The two panes are ordinary agent
+views moved between grid columns with `Grid.SetColumn` — **never re-parented**, so both WebViews (and
+their live transcripts) survive the switch, which is the whole reason the tab surface is built the
+way it is (see below).
 
 The three approval services are per-agent for **correctness**, not tidiness. Shared, they break
 in ways that are invisible until a second tab exists: `WinUiApprovalService` holds the
@@ -117,18 +130,33 @@ a casing difference.
 
 ### Context snapshots
 
-Switching a model clears the conversation (a different model mid-history is a different
-conversation). The instant before it clears, the outgoing conversation is captured as a
-`ContextSnapshot` — origin model, timestamp, a deterministic recap, and the full history. The
-recap comes from `HistorySummarizer`, a port of the harness's own (private) compaction summary fed
-by the public `AIService.GetHistoryAsync()` — so no submodule change. The **Snapshots** rail icon
-opens a global panel (the `SnapshotStore` is app-wide, one list for every tab); **Import** arms a
-snapshot's recap to ride along, invisibly, with the active agent's next message — carrying context
-into any model. `Take snapshot` on a tab's `⋯` menu captures on demand without switching.
-
-The snapshot keeps the full history so a richer LLM summary can be generated later (the model
-reserves `AiRecap`, the `Tag` flips `Light`→`AI`); that "Enhance" action waits on a small no-tools
-completion seam added at the next harness pin roll. Snapshots are session-scoped and in memory only.
+A snapshot is a portable, AI-written recap of a conversation — save the gist of one agent's
+context and carry it into another model or a fresh agent. Snapshots are offered when switching a
+model would clear the conversation, and on demand via `Take snapshot` (tab `⋯` menu), which goes
+straight to the save step. The recap is generated by `SnapshotEnhancer` (a bare, tool-less Ollama
+kernel, map-reduce over the full history so nothing is truncated) using a summarizer model you
+pick; a snapshot is therefore always born with a real recap — there is no "light"/un-enhanced state.
+Leave the name blank and the summarizer proposes a short title, which is then made unique against
+existing titles in code (`SnapshotNaming`) — an LLM can't be trusted to guarantee that itself.
+
+The **Snapshots** rail icon opens a global panel (the `SnapshotStore` is app-wide, one list for
+every tab, **persisted** to `snapshots.json`). Cards **group by project** and are **searchable**,
+and each project group is a collapsible `Expander` whose fold state is remembered
+(`PanelState` → `panel-state.json`). **Import** arms a snapshot's recap to ride along, invisibly,
+with the active agent's next message — carrying context into any model. The rail badge is an
+**unread count** (snapshots captured since you last opened the panel), not a running total, and
+clears when you open it.
+
+### Session history (reopen closed conversations)
+
+Closing an agent no longer discards its conversation — it **archives** it. `SessionArchiveStore`
+keeps an app-wide index (`sessions.json`) of closed conversations; the transcript, model memory, and
+conversation-log journals stay on disk (see [docs/session-persistence.md](docs/session-persistence.md)).
+The **History** rail panel lists them (grouped by project, searchable, collapsible), and **Open**
+reopens one as a fresh tab on its original persist-key so the normal restore cascade replays the
+transcript and — when the model supports it — rehydrates the full memory. `/clear` still forgets a
+conversation for good; only *closing* softened from "gone" to "recoverable." The archive is capped
+(newest 60); evicting a row deletes its journals so the on-disk stores stay bounded.
 
 ### Why the tab strip isn't a `TabView`
 
@@ -158,11 +186,22 @@ within 24 hours.
 - Agent tabs — `+` opens another agent (`Agent 1`, `Agent 2`, …) with its own
   conversation, project folder, model, and settings; an approval waiting in a
   background agent badges its tab and the toast names it. Each tab's `⋯` menu:
-  Rename, Take snapshot, Export transcript, Close (greyed on the last agent). The
-  header model opens a quick-switch dropdown (cloud first, `cloud`/`local` badges)
-- Context snapshots — the conversation is captured the instant a model switch would
-  clear it (and on demand via `⋯` → Take snapshot); a global left-rail panel lists
-  every tab's snapshots and Import carries one into the active agent's next message
+  Rename, Take snapshot, Export transcript, Close. The header model opens a
+  quick-switch dropdown (cloud first, `cloud`/`local` badges). Closing the last
+  agent is allowed and leaves an empty state that shows the chat background
+- Compare view — the **Split** button shows two agents side by side in a resizable
+  split for comparing their output; the compared pair is a remembered, explicit
+  choice, so clicking other tabs navigates without disturbing it
+- Session history — closing an agent archives its conversation instead of deleting
+  it; the **History** panel reopens any past conversation as a new tab (with its
+  transcript, and full memory when the model supports it), grouped by project and
+  searchable. `/clear` still forgets for good
+- Context snapshots — save an AI-written recap of a conversation (summarized by a
+  model you pick) and Import it into another model or a fresh agent; a global
+  left-rail panel lists them, **persisted**, grouped by project, searchable, with
+  collapsible groups. Unnamed snapshots get an auto-generated, unique title
+- Rail badges on History and Snapshots are unread counts that clear when you open
+  the panel (persisted), not running totals
 - Sidebar: Settings and MCP as full-screen pages, acting on the selected agent
   - Settings — the whole config as a native form (toggles, sliders, number boxes,
     grouped Appearance/Connection/Generation/Behavior/Limits/Integrations); every
@@ -176,6 +215,7 @@ within 24 hours.
     progress, model picker, cloud-auth check + sign-in walkthrough
   - `/model`, `/force-skill`, `/music-playlist` — pickers
   - 401 auto-recovery — a cloud 401 offers the `ollama signin` walkthrough inline
+- Branded application icon across the exe, taskbar, and window title bar
 - Update check against this repo's GitHub Releases (24h throttle, fail-silent)
 
 Not ported (yet): matrix easter eggs, terminal theme service (N/A).

docs/session-persistence.md

@@ -24,6 +24,8 @@ Each tier ships independently and degrades gracefully into the one below it.
 |------|---------------|-------|-----------|
 | 1 | Workspace shape: tabs, titles, folders, models, active tab | `workspace.json` | Saved on every structural change + close; restored at launch |
 | 1 | Snapshots | `snapshots.json` | Rewritten on add/remove; loaded at construction |
+| 1 | Closed-conversation index (History) | `sessions.json` | Rewritten on close/reopen/delete; points at the retained per-key journals below |
+| 1 | Panel UI prefs: collapsed groups + per-panel "last seen" unread marks | `panel-state.json` | Rewritten on fold/unfold and when a panel is opened |
 | 2 | The visible transcript | `transcripts/<key>.jsonl` | Append-on-write journal of every HTML block; replayed into the WebView on restore |
 | 3 | The model's memory | `histories/<key>.json` | `AIService.ExportHistoryJson()` at every turn end (write-then-rename); `TryRestoreHistoryJson()` on restore |
 | 3 fallback | A plain-text tail of the dialogue | `conversations/<key>.jsonl` | Armed as imported background on the next send when full fidelity can't apply |
@@ -63,18 +65,43 @@ both sides of the concept line:
 was cleared, there is nothing to carry). If the verbatim import fails, the offer stays up and
 the snapshot path remains as salvage.
 
-## Where snapshots are left off (future building)
+## The History archive — reopening closed conversations
 
-Snapshots persist across launches now, they record their project root, and IDs survive — but
-the panel hasn't caught up: **no grouping by project, no search, and the import UX is
-unchanged.** Those are polish items waiting for the snapshot library to grow now that it's
-durable. Nothing broken, just room.
+The per-key journals turned out to support more than restoring the tabs open at close: they back a
+**History panel** that reopens *any* conversation you've closed. This required one deliberate change
+to the retention model.
 
-Other known headroom, in rough order of value:
+Closing a tab used to delete its journals outright — "closed tab = conversation gone." That made
+the memory/knowledge split lopsided: the only way context survived was to still be open at launch.
+Now closing **archives** instead:
+
+- `SessionArchiveStore` keeps an app-wide index (`sessions.json`) of closed conversations — the
+  cheap metadata (title, project, model, closed-at, turn count, first message), not the heavy
+  parts. The transcript/log/history journals it points at are the same per-key stores a live tab
+  uses; they simply aren't deleted on close anymore.
+- **Reopen** recreates a tab on the archived persist-key and lets the normal restore cascade run —
+  so a reopened conversation replays its transcript and, when the model can take it, rehydrates its
+  full memory. The row leaves the archive (it's live again) and re-files itself on the next close.
+- The archive is capped at the newest 60; evicting a row deletes its journals, so the on-disk
+  stores stay bounded even for someone who never runs `/clear`.
+- The startup orphan sweep now keeps *archived* keys alongside *open* ones — only genuinely
+  orphaned journals (crash leftovers, pruned folders) are swept.
+
+The design rule held: `/clear` still forgets (deletes the files, never archives). Only the meaning
+of *closing* softened from "gone" to "recoverable." A session that never had a real turn is dropped
+on close regardless — there's nothing worth reopening.
+
+Both panels grew the same shape at the same time: cards **group by project**, a **search** box
+filters them, and each project group is a **collapsible** `Expander` whose fold state persists
+(`panel-state.json`). Their rail badges became **unread counts** — items newer than the last time
+you opened that panel — which clear on open and whose "last seen" marks also persist. Snapshots
+gained **AI-generated titles** (unique-checked in code) when saved unnamed, and Import now gets out
+of the way so the chat's "context armed" confirmation is what you see.
+
+## Future building
+
+In rough order of value:
 
-- **Session history browser** — the per-key journals already on disk would support a
-  "reopen any past conversation as a new tab" picker (Claude Code's `/resume` equivalent),
-  not just restoring the tabs that were open at close.
 - **Summarize-at-restore upgrade** — the tail-brief fallback could run `HistorySummarizer`
   over the stored dialogue instead of excerpting it, trading an LLM call for better coverage
   of long sessions.

src/MandoCode.Desktop.Tests/MandoCode.Desktop.Tests.csproj

@@ -21,6 +21,16 @@
     <Compile Include="..\MandoCode.Desktop\Services\GitQuickStatus.cs" Link="src\GitQuickStatus.cs" />
     <Compile Include="..\MandoCode.Desktop\Services\WorkspaceDeltaTracker.cs" Link="src\WorkspaceDeltaTracker.cs" />
     <Compile Include="..\..\MandoCode\src\MandoCode\Models\DiffModels.cs" Link="src\DiffModels.cs" />
+
+    <!-- Session-archive/snapshot display derivations are pure logic (path parsing, placeholders);
+         the store classes come along because the entry types live beside them, but no test
+         instantiates a store (they hit fixed LocalAppData paths). -->
+    <Compile Include="..\MandoCode.Desktop\Services\ContextSnapshot.cs" Link="src\ContextSnapshot.cs" />
+    <Compile Include="..\MandoCode.Desktop\Services\SnapshotNaming.cs" Link="src\SnapshotNaming.cs" />
+    <Compile Include="..\MandoCode.Desktop\Services\SessionArchiveStore.cs" Link="src\SessionArchiveStore.cs" />
+    <Compile Include="..\MandoCode.Desktop\Services\TranscriptJournal.cs" Link="src\TranscriptJournal.cs" />
+    <Compile Include="..\MandoCode.Desktop\Services\ConversationLog.cs" Link="src\ConversationLog.cs" />
+    <Compile Include="..\MandoCode.Desktop\Services\SessionHistoryStore.cs" Link="src\SessionHistoryStore.cs" />
   </ItemGroup>
 
 </Project>