feat(ui): a Claude-Desktop-style home for every workspace

/workspace?lane=<id> opens on the workspace's home (WorkspaceHome): a prompt
box whose Start opens a new session in the first free pane slot, Recents (a
live session attaches its pane, any other opens its transcript, nothing
resumes), and Instructions / Memory / Context / Folder. Instructions live in
lanes.instructions, extra folders and uploaded files in the new lane_sources
table (copies under <data dir>/workspace-context/<lane id>/); spawnRun reads
them from the lane's rows and hands Claude --add-dir + an appended system
prompt file, Codex --add-dir + developer_instructions. Memory is read-only.

Every dashboard pane carries AGENTHUB_RUN_ID; hooks forward it and the run
records which session the pane holds (a Claude pane follows /clear and
/resume but not a nested claude -p), so the sidebar and notifications open
the right pane (&run=). Settings loses its Projects group; Worktrees now
decides which worktrees Add folder suggests.

docs/API.md

@@ -1120,6 +1120,40 @@ POST /api/locks/:name/release
 - **409** `{ "error": { "code": "ENOTHOLDER", "message": "...", "currentHolder": "lane1" } }` — `holder` doesn't match the current owner; a release never trusts its caller, same rule every other destructive path in this project follows.
 - **404** `{ "error": { "code": "ENOLOCK", "message": "no such lock: build" } }` — nothing by that name is held.
 
+#### Workspace context: instructions, folders, context files, memory
+
+```http
+GET    /api/lanes/:id/sources
+PUT    /api/lanes/:id/instructions        {"instructions": "…" | null}
+POST   /api/lanes/:id/sources/folder      {"path": "/abs/dir"}
+POST   /api/lanes/:id/sources/file        raw body, Content-Type: application/octet-stream, X-File-Name: <URI-encoded name>
+DELETE /api/lanes/:id/sources/:sourceId
+GET    /api/lanes/:id/memory
+```
+
+What a workspace's home page edits (`server/lib/lane-sources.js`, `server/routes/lane-sources.js`). `GET …/sources` and every write answer the same view:
+
+```jsonc
+{
+  "instructions": "Always answer in Vietnamese.",
+  "supported": true,              // the workspace's tool can take them (claude, codex)
+  "maxFileBytes": 10485760,
+  "maxInstructions": 16000,
+  "sources": [
+    { "id": 3, "kind": "folder", "path": "/home/u/shared", "name": "shared", "size": null, "added_at": "…", "missing": false },
+    { "id": 4, "kind": "file", "path": "<data dir>/workspace-context/12/spec.pdf", "name": "spec.pdf", "size": 20480, "added_at": "…", "missing": false }
+  ]
+}
+```
+
+- **Instructions** — the `instructions` key is required (`400 EBADFIELD` without it), a string or `null`; blank clears; over 16 000 characters is `413 ETOOBIG`. The lane is re-broadcast (`lane_update`). The text is stored in `lanes.instructions` but is NOT part of the lane payload (`GET /api/lanes`, `lane_update`) — read it here.
+- **Folder** — must be absolute, exist and be a directory (`400 EBADPATH`), must not be or contain the OS home (`400 EBADHOME`), and must not be the workspace's own folder or one it already has (`400 EDUP`). Stored by real path. Removing it only drops the row.
+- **File** — up to 10 MB (`413 ETOOBIG`), not empty (`400 EEMPTY`). AgentHub stores it under `<data dir>/workspace-context/<lane id>/` with a name it derives from `X-File-Name` (directory parts and path characters dropped, `name (2).ext` on a clash), so a request never names a path. Removing it deletes that copy. At most 50 sources per workspace (`400 ETOOMANY`).
+- **Memory** — read-only: the folder's `CLAUDE.md`, `.claude/CLAUDE.md`, `CLAUDE.local.md`, `AGENTS.md`, and for a Claude workspace `<CLAUDE_HOME>/projects/<encoded cwd>/memory/*.md` — `{files: [{label, path, size, mtime, truncated, content}]}`, each at most 256 KB of content.
+- Every write is same-origin only (`403 EBADORIGIN`); an unknown workspace is `404 ENOLANE`, an unknown source `404 ENOSOURCE`.
+
+At spawn (`spawnRun`, both `POST /api/lanes/:id/start` and `POST /api/run`) the pane gets, from these rows: Claude — `--add-dir <folders…> [<context dir>]` first, then `--append-system-prompt-file=<data dir>/workspace-prompts/<lane id>.md`, a file rewritten at every spawn holding the instructions + the context file list + the extra folders; Codex — one `--add-dir <dir>` per folder (and the context dir) and `-c developer_instructions=<same text as a TOML string>` (above 6 KB as the escaped TOML string, one line pointing at that file instead; nothing when that file could not be written). Any other tool gets none of it (`supported: false`). A folder or file that vanished is skipped.
+
 #### Projects (workspaces grouped by repository)
 
 ```http
@@ -1127,7 +1161,7 @@ GET /api/projects
 POST /api/projects/refresh
 ```
 
-Every workspace grouped under the git repository it belongs to, for the sidebar's project tree. A project's `root` is the repo's MAIN worktree top level (`git rev-parse --git-common-dir`, realpath); workspaces outside any repo form the `root: null` pseudo-project, listed last. `worktrees` is `git worktree list` for that repo (a worktree whose directory is gone is left out); `workspace_id` is the lane sitting exactly on that path, else `null` — an **untracked worktree** the UI offers to adopt. A lane on a subdirectory of a worktree is in `workspaces` but marks no worktree. `source` is `"claude"` under `<root>/.claude/worktrees/`, `"agenthub"` under `LANES_ROOT`, else absent.
+Every workspace grouped under the git repository it belongs to; a workspace home's **Add folder** suggests the untracked worktrees of its own repo from it. A project's `root` is the repo's MAIN worktree top level (`git rev-parse --git-common-dir`, realpath); workspaces outside any repo form the `root: null` pseudo-project, listed last. `worktrees` is `git worktree list` for that repo (a worktree whose directory is gone is left out); `workspace_id` is the lane sitting exactly on that path, else `null` — an **untracked worktree** the UI offers to adopt. A lane on a subdirectory of a worktree is in `workspaces` but marks no worktree. `source` is `"claude"` under `<root>/.claude/worktrees/`, `"agenthub"` under `LANES_ROOT`, else absent.
 
 ```jsonc
 {
@@ -1146,7 +1180,7 @@ Every workspace grouped under the git repository it belongs to, for the sidebar'
 }
 ```
 
-Both git reads are cached in memory — a directory's root for the life of the server, a repo's worktree list for 30 s — and the lane ↔ worktree match is recomputed on every call, so a new or removed workspace needs no invalidation. This route is read on demand (the client re-reads it when the set of workspaces changes), never on the polled `GET /api/lanes`. `POST /api/projects/refresh` drops both caches first and answers the same shape; it is same-origin only (`403 EBADORIGIN`).
+Both git reads are cached in memory — a directory's root for the life of the server, a repo's worktree list for 30 s — and the lane ↔ worktree match is recomputed on every call, so a new or removed workspace needs no invalidation. This route is read on demand (a workspace home's Add folder suggestions), never on the polled `GET /api/lanes`. `POST /api/projects/refresh` drops both caches first and answers the same shape; it is same-origin only (`403 EBADORIGIN`).
 
 ### Sessions
 

docs/DATABASE.md

@@ -532,6 +532,23 @@ CREATE TABLE antigravity_conversations (
 );
 ```
 
+### lane_sources (and `lanes.instructions`)
+
+A workspace's own context, as on its home page (`server/lib/lane-sources.js`). `lanes.instructions` (TEXT, nullable, ≤ 16 000 characters) is appended to every new pane's system prompt; `lane_sources` holds its extra **folders** (the user's directories, never deleted by AgentHub) and uploaded context **files** (AgentHub's own copies under `<data dir>/workspace-context/<lane id>/`, deleted with the row and with the workspace). Both are read at spawn from these rows only (`launchExtras`), never from a request. Both are additive migrations; the rows cascade when the lane row is deleted.
+
+```sql
+CREATE TABLE lane_sources (
+    id INTEGER PRIMARY KEY,
+    lane_id INTEGER NOT NULL REFERENCES lanes(id) ON DELETE CASCADE,
+    kind TEXT NOT NULL CHECK (kind IN ('folder', 'file')),
+    path TEXT NOT NULL,     -- real path of the folder, or AgentHub's copy of the file
+    name TEXT NOT NULL,     -- folder basename / the stored file name
+    size INTEGER,           -- bytes, files only
+    added_at TEXT NOT NULL
+);
+CREATE INDEX idx_lane_sources_lane ON lane_sources(lane_id);
+```
+
 ---
 
 ## Indexes

docs/LANES.md

@@ -391,10 +391,11 @@ The dashboard web UI merges workspaces and runs into a single **Workspace** page
 
 - **No page header.** The page title and the four counters (`lanes`, `running`, `needs you`, `dead`) are gone: the sidebar's workspace list shows every workspace with its own status dot, and the status bar at the bottom of every page counts running and need-you workspaces. `GET /api/lanes` still returns `counts` for other callers.
 - **The sidebar's workspace list picks the workspace** — on every page, between the nav and the footer (`client/src/components/WorkspaceTree.tsx`), shaped like Claude Desktop's project list: every workspace on ONE level (no repo grouping, no worktree rows), in your stored order. A row (`WorkspaceRow.tsx`) is a chevron, a status dot (green = active, pulsing while running; amber row = needs you; red = dead or error; grey = idle), the title or folder name and the tool's icon, with `+` (open it for a new session) and `⋯` on hover. Clicking the name opens `/workspace?lane=<id>` and expands the row: the URL is the selection, so a notification link, F5 and the back button all land on the same workspace, and a bare `/workspace` reopens the last one shown (`agenthub.workspace.selected`) or the first. The header has search (workspace names and paths, plus the names of the sessions listed) and `+` (Add workspace). In the collapsed rail the list is a single icon that opens the sidebar.
-- **A workspace's sessions** — the chevron expands the row to its sessions (`WorkspaceSessionList.tsx`: `GET /api/sessions?cwd=&tool=`, the newest 20, re-read when the workspace's status or session moves; which rows are expanded is kept in `agenthub.sidebar.projects` → `expanded`). A filled dot marks a session that still has a live pane (a `GET /api/run` handle carrying its session id): clicking it opens `/workspace?lane=<id>&run=<runId>`, which ATTACHES pane 0 to that tmux session (`attachRequest` on `LaneConsolePane`) — it starts nothing and resumes nothing. Any other session opens its read-only transcript at `/sessions/<id>`; resuming it is a separate, explicit action there, because a resume re-reads the whole transcript into context.
+- **A workspace's sessions** — the chevron expands the row to its sessions (`WorkspaceSessionList.tsx`: `GET /api/sessions?cwd=&tool=`, the newest 20, re-read when the workspace's status or session moves; which rows are expanded is kept in `agenthub.sidebar.projects` → `expanded`). A filled dot marks a session that still has a live pane (a `GET /api/run` handle carrying its session id — every pane the dashboard starts carries `AGENTHUB_RUN_ID=<its tmux name>`, the hook handler forwards it as `run_id`, and `bindRunSession` in `server/routes/hooks.js` records the hook's session on that run: the first session always, afterwards — for a Claude pane — only a `SessionStart` that is not a fresh `startup` (`/clear`, `/resume`), so a `claude -p` the agent runs inside the pane never takes it over; the rule is Claude-only, and a Codex or Antigravity pane follows every new session): clicking it opens `/workspace?lane=<id>&run=<runId>`, which ATTACHES pane 0 to that tmux session (`attachRequest` on `LaneConsolePane`) — it starts nothing and resumes nothing. Any other session opens its read-only transcript at `/sessions/<id>`; resuming it is a separate, explicit action there, because a resume re-reads the whole transcript into context.
 - **Row menu** — right-click a row, or its `⋯` button: Start/Stop (slot 0), Rename, the Model (AI Router) select, Create/update readme file (Claude only), New workspace here…, Copy path, Reset worktree… (managed only) and Delete workspace…, each the call the rest of the UI already makes. Delete is record-only exactly as before (see "Removing a workspace").
-- **Untracked worktrees** are no longer listed in the sidebar; the settings that hid them (`showUntracked`, hidden sources `claude` = `<repo>/.claude/worktrees/*` and `agenthub` = `LANES_ROOT`, Settings → Git → **Worktrees** and a project's own page) are kept for the workspace page's folder suggestions.
-- **A project's settings page** — Settings → Projects → <repo> shows the repository's root, main branch and worktree count, links each of its workspaces, holds the per-project worktree override above, and offers **Forget all workspaces…**: after one confirm listing them it runs the same `remove` as the row menu for each (preflight, then `POST /api/lanes/:id/remove` with those facts as `expect`) and stops at the first refusal. Forgetting drops AgentHub's records only — nothing on disk is deleted.
+- **The workspace home** — `/workspace?lane=<id>` opens on the workspace's home (`client/src/components/lanes/WorkspaceHome.tsx`), shaped like a Claude Desktop project page: the name (rename from its `⋯` menu, which is the sidebar row menu), a prompt box with the tool's model picker (and Claude's permission mode) whose **Start** opens a NEW session in the first pane slot with no live run (0–3, `POST /api/lanes/:id/start {slot}`; all four busy is refused) and then shows it, and **Recents** — the workspace's sessions, a live one opening its pane and any other its read-only transcript, exactly like the sidebar. On the right sit the workspace's own context: **Instructions** (appended to every new session's system prompt), **Memory** (read-only: the folder's CLAUDE.md / AGENTS.md family and Claude's auto memory), **Context** (uploaded files, ≤ 10 MB each, stored by AgentHub) and **Folder** (the workspace's own folder plus extra ones, with the repo's untracked worktrees suggested). Only Claude and Codex panes can take them (`--add-dir`, `--append-system-prompt-file=` / `-c developer_instructions=`); for any other tool the page says so and its panes start without them. See `docs/API.md` → Workspace context. The home HIDES the session view with CSS — the console never unmounts behind it.
+- **The session view** — `/workspace?lane=<id>&run=<runId>` (a live session picked in the sidebar or Recents, or one just started) shows today's console, split panes and the Files / Changes / Sessions panel, with pane 0 attached to that run; the header's back arrow returns to the home. A browser notification for a workspace with a live pane opens it here directly.
+- **Untracked worktrees** are no longer listed in the sidebar; Settings → Git → **Worktrees** (`showUntracked`, hidden sources `claude` = `<repo>/.claude/worktrees/*` and `agenthub` = `LANES_ROOT`) now decides which of them the home's Add folder suggests.
 - **No workspaces yet** — the page shows a single banner (`lane-empty`): icon, one line of what a workspace is, the CLI equivalent (`agenthub lanes add --cwd $(pwd)`) and an **Add workspace** affordance. The whole banner IS the button — clicking anywhere on it opens the Add-workspace modal. The banner stays compact on purpose: the run setup form below it is what needs the height.
 - **Reordering** — drag a row onto another, or press **Alt+↑/↓** with a row focused. The order is a **per-viewer preference**, not a workspace fact: it persists to `localStorage` (`agenthub.workspace.laneOrder`) and writes nothing server-side — `GET /api/lanes` and `agenthub lanes` keep answering in id order, and the order does not follow you to another browser. A workspace the stored order has never seen lands at the END; a stored id whose workspace is gone is skipped.
 - **Renaming a workspace** — double-click its sidebar row (or Rename in the row menu) to edit in place. **Enter** saves via `PATCH /api/lanes/:id` with `{title}`, **Escape** and clicking away both cancel, and saving an empty name clears the title, which puts the folder name back in its place. Renaming is display-only — a managed workspace's branch name was slugified from its title once, at creation.