Add local history cache and storage port

FEATURES.md

@@ -121,6 +121,8 @@ Everything below ships in the first usable release. The MVP is deliberately narr
 | Voice UI | Satellite selector, participant list, mute/deafen, per-user volume, push-to-talk, grid/speaker layouts | [04-clients/01-desktop](spec/04-clients/01-desktop.md) |
 | Message outbox | Messages held during disconnection, sent on reconnect, cleared after server ack | [04-clients/01-desktop](spec/04-clients/01-desktop.md) |
 | Memory discipline | Paginated chat (200 msgs/channel in DOM), image resizing via Rust, debounced resizes | [04-clients/01-desktop](spec/04-clients/01-desktop.md) |
+| Local history cache | On-device persistent cache (IndexedDB on web, SQLite on desktop); cache-first prefill, progressive rendering, sliding window; offloads `chathistory` from Uplink | [04-clients/04-local-cache](spec/04-clients/04-local-cache.md) |
+| Storage management | Settings -> Storage: per-buffer stats, eviction, JSON export, configurable per-buffer cap | [04-clients/04-local-cache](spec/04-clients/04-local-cache.md) |
 | `orbit://` + `satellite://` URI schemes | Deep links to server/channel/voice; standalone Satellite links | [04-clients/01-desktop](spec/04-clients/01-desktop.md) |
 | Screen sharing | Share screen in voice sessions | [02-satellite](spec/02-components/02-satellite.md) |
 | Multi-server client | Connect to multiple Orbit servers simultaneously | - |
@@ -245,6 +247,8 @@ Federation requires server-to-server linking that is absent from stock Ergo. It
 | E2E encrypted file uploads | Client-side encryption before Depot upload | [03-depot](spec/02-components/03-depot.md) |
 | Richer presence | Presence history (last online), structured status states, server-managed avatars | [01-uplink/04-presence](spec/02-components/01-uplink/04-presence.md) |
 | Channel renaming | Optional, capability-gated (`draft/channel-rename`); blocked on registered channels, so `display-name` metadata is the rename path for established channels | [01-uplink/01-overview](spec/02-components/01-uplink/01-overview.md#channel-renaming) |
+| Client-side search index | Local inverted index / SQLite FTS5 over the on-device cache; answers most searches offline and offloads the server's history backend | [04-clients/04-local-cache](spec/04-clients/04-local-cache.md#evaluation-performance-and-limits) |
+| Chat list virtualization | Mount only the visible message range to push effective DOM cost below the live-window cap for very large buffers | [04-clients/04-local-cache](spec/04-clients/04-local-cache.md#evaluation-performance-and-limits) |
 
 ## Research
 

README.md

@@ -35,7 +35,7 @@ The `spec/` directory contains the full design spec:
 | [Architecture](spec/01-architecture/) | System overview, design philosophy, component glossary, platform comparison |
 | [Components](spec/02-components/) | Uplink (incl. tag namespace and trust model), Satellite, Depot, Transponder |
 | [Identity and Auth](spec/03-identity/) | Authentication, permissions |
-| [Clients](spec/04-clients/) | Desktop, web app, widget |
+| [Clients](spec/04-clients/) | Desktop, web app, widget, local history cache |
 | [Infrastructure](spec/05-infrastructure/) | DNS discovery, deployment, monorepo |
 | [Next](spec/06-next/) | Mobile, bot API, push delivery, E2E encryption, server discovery, Satellite gateway |
 | [Decisions](spec/0A-decisions/) | ADRs, open questions, out-of-scope |

spec/04-clients/01-desktop.md

@@ -174,7 +174,7 @@ DNS SRV resolution is handled by the desktop client's Rust resolver. For the ful
 
 | Concern            | Strategy                                                                                                                                   |
 |--------------------|--------------------------------------------------------------------------------------------------------------------------------------------|
-| Chat history       | Paginated loading. Keep at most 200 messages per channel in the DOM. Older messages are evicted and re-fetched on scroll-up via `chathistory`. |
+| Chat history       | Paginated loading. Keep at most 200 messages per channel in the DOM (the *live window*). Older messages are evicted from the DOM and served from the on-device [local cache](04-local-cache.md), which falls back to `chathistory` only when the cache is exhausted. |
 | Image rendering    | Images are proxied and resized by the Rust backend (or server-side) before display. No raw multi-MB images loaded into the WebView.        |
 | Large IPC payloads | File downloads and bulk history loads are served via Tauri's custom protocol handler (`tauri://`).                |
 | Layout thrashing   | Resize events are debounced aggressively (200ms minimum). This works around a known WebKitGTK memory leak on Linux triggered by rapid resize cycles. |

spec/04-clients/02-web-app.md

@@ -31,6 +31,7 @@ export interface Platform {
   deepLinks: DeepLinkPort | null // null in the browser
   fileTransfer: FileTransferPort
   dns: DnsPort | null            // null in the browser; resolver endpoint used instead
+  historyCache: HistoryCachePort | null // IndexedDB on web, SQLite on desktop; null when storage is blocked
 }
 ```
 
@@ -91,6 +92,7 @@ The complete capability comparison across all three surfaces:
 |------------------------------------------|--------------------------------|---------------------------------------------|----------------------------------------|
 | Text chat (full)                         | Yes                            | Yes                                         | Yes                                    |
 | Message history / scrollback             | Yes                            | Yes                                         | Yes (limited to recent on load)        |
+| Persistent local history cache           | Yes (SQLite, disk-bounded)     | Yes (IndexedDB, quota-bounded, best-effort) | Ephemeral (in-memory; cache may be `null`) |
 | Message retractions                      | MVP (via `draft/message-redaction`) | MVP (via `draft/message-redaction`)    | MVP (via `draft/message-redaction`)    |
 | Message editing                          | Post-Uplink                    | Post-Uplink                                 | Post-Uplink                            |
 | Rich rendering (links, images, Markdown) | Yes                            | Yes                                         | Yes                                    |