core/docs/DESIGN-0.21.0.md

# Design — v0.21.x: Workspaces + Extension Surfaces

**Status:** Planning
**Depends on:** v0.20.0 (notifications), v0.17.2 (CM6), v0.11.0 (extension foundation)
**Feeds into:** v0.22.0 (smart routing), v0.23.0 (multi-participant channels)

---

## Guiding Principle

The **workspace** is a platform primitive — not an editor-mode concept. Even in
pure chat mode, uploading a zip, having the AI operate on real files at real
paths, and downloading the result as an archive is a first-class workflow. Every
surface (chat, editor, article, future modes) benefits from workspace access.

This changes the layering: workspace infrastructure lands first as foundational
storage, then surfaces consume it.

---

## Release Decomposition

```
v0.21.0  Workspace Storage (platform primitive)
           │
v0.21.1  Workspace Tools + Channel/Project Binding
           │
v0.21.2  Workspace Indexing + Semantic Search
           │
v0.21.3  Surface Infrastructure + REPL
           │
v0.21.4  Git Integration
           │
v0.21.5  Editor Surface (Development Mode)
           │
v0.21.6  Article Surface + Document Output Pipeline
```

---

## v0.21.0 — Workspace Storage

Pure backend. No tools, no UI, no surfaces. Just the storage primitive with
full CRUD API and archive support.

### Data Model

**`workspaces` table**

| Column | Type | Notes |
|--------|------|-------|
| `id` | UUID | PK |
| `owner_type` | TEXT | `user`, `project`, `channel`, `team` |
| `owner_id` | UUID | FK polymorphic |
| `name` | TEXT | display name |
| `root_path` | TEXT | PVC-relative path: `workspaces/{id}` |
| `max_bytes` | BIGINT | quota (NULL = system default) |
| `status` | TEXT | `active`, `archived`, `deleting` |
| `created_at` | TIMESTAMPTZ | |
| `updated_at` | TIMESTAMPTZ | |

Index: `(owner_type, owner_id)` — lookup workspace(s) for a given owner.

**`workspace_files` table** (metadata index — filesystem is source of truth)

| Column | Type | Notes |
|--------|------|-------|
| `id` | UUID | PK |
| `workspace_id` | UUID | FK → workspaces |
| `path` | TEXT | relative path from workspace root: `src/main.go` |
| `is_directory` | BOOLEAN | |
| `content_type` | TEXT | MIME type (detected or inferred) |
| `size_bytes` | BIGINT | 0 for dirs |
| `sha256` | TEXT | content hash (NULL for dirs) |
| `created_at` | TIMESTAMPTZ | |
| `updated_at` | TIMESTAMPTZ | |

Index: `UNIQUE (workspace_id, path)` — one entry per path.
Index: `(workspace_id, content_type)` — filter by type.

Design note: the DB index is a metadata cache. The PVC filesystem is the source
of truth. Syncing happens on write operations and optionally via a reconcile
endpoint. This avoids the complexity of fsnotify while keeping queries fast.

### Filesystem Layout (PVC)

```
/data/storage/
  attachments/         # existing (v0.12.0)
  processing/          # existing extraction queue
  workspaces/          # NEW
    {workspace_id}/
      .workspace.json  # metadata: owner, quotas, created_at
      files/           # actual file tree root
        src/
          main.go
        README.md
```

Why a separate `files/` subdirectory: keeps workspace metadata (`.workspace.json`,
future `.git/` in v0.21.4) out of the user's file namespace.

### Store Interface

```go
type WorkspaceStore interface {
    // CRUD
    Create(ctx context.Context, w *models.Workspace) error
    GetByID(ctx context.Context, id string) (*models.Workspace, error)
    Update(ctx context.Context, id string, patch models.WorkspacePatch) error
    Delete(ctx context.Context, id string) error

    // Ownership lookup
    GetByOwner(ctx context.Context, ownerType, ownerID string) (*models.Workspace, error)
    ListByOwner(ctx context.Context, ownerType, ownerID string) ([]models.Workspace, error)

    // File index
    UpsertFile(ctx context.Context, f *models.WorkspaceFile) error
    DeleteFile(ctx context.Context, workspaceID, path string) error
    DeleteFilesByPrefix(ctx context.Context, workspaceID, prefix string) error
    GetFile(ctx context.Context, workspaceID, path string) (*models.WorkspaceFile, error)
    ListFiles(ctx context.Context, workspaceID, prefix string, recursive bool) ([]models.WorkspaceFile, error)

    // Stats
    GetDiskUsage(ctx context.Context, workspaceID string) (int64, error)
}
```

### Workspace FS (Filesystem Operations)

Separate from the store — this operates on PVC, not DB.

```go
type WorkspaceFS struct {
    basePath string          // e.g. /data/storage/workspaces
    store    WorkspaceStore  // for metadata sync
}

// File CRUD — all paths relative to workspace root
func (fs *WorkspaceFS) ReadFile(ctx context.Context, w *models.Workspace, path string) (io.ReadCloser, int64, error)
func (fs *WorkspaceFS) WriteFile(ctx context.Context, w *models.Workspace, path string, r io.Reader, size int64) error
func (fs *WorkspaceFS) DeleteFile(ctx context.Context, w *models.Workspace, path string) error
func (fs *WorkspaceFS) Mkdir(ctx context.Context, w *models.Workspace, path string) error
func (fs *WorkspaceFS) Stat(ctx context.Context, w *models.Workspace, path string) (*models.WorkspaceFile, error)
func (fs *WorkspaceFS) ListDir(ctx context.Context, w *models.Workspace, prefix string, recursive bool) ([]models.WorkspaceFile, error)

// Tree: returns full file listing with sizes (for file tree UI)
func (fs *WorkspaceFS) Tree(ctx context.Context, w *models.Workspace) ([]models.WorkspaceFile, error)

// Archive operations
func (fs *WorkspaceFS) ExtractArchive(ctx context.Context, w *models.Workspace, r io.Reader, format string) (int, error)
func (fs *WorkspaceFS) CreateArchive(ctx context.Context, w *models.Workspace, format string) (io.ReadCloser, error)

// Maintenance
func (fs *WorkspaceFS) Reconcile(ctx context.Context, w *models.Workspace) error  // sync FS → DB index
func (fs *WorkspaceFS) Destroy(ctx context.Context, w *models.Workspace) error    // rm -rf + DB cleanup
```

WriteFile updates the DB index (upsert workspace_files) after successful write.
DeleteFile removes the DB row. Reconcile walks the FS and patches any drift.

### API Endpoints

```
POST   /api/v1/workspaces                          # create workspace
GET    /api/v1/workspaces/:id                       # get metadata
PATCH  /api/v1/workspaces/:id                       # update name/quota
DELETE /api/v1/workspaces/:id                       # delete (async cleanup)

GET    /api/v1/workspaces/:id/files?path=&recursive= # list files
GET    /api/v1/workspaces/:id/files/read?path=       # read file content
PUT    /api/v1/workspaces/:id/files/write?path=       # write file (body = content)
DELETE /api/v1/workspaces/:id/files?path=             # delete file/dir
POST   /api/v1/workspaces/:id/files/mkdir?path=       # create directory

POST   /api/v1/workspaces/:id/archive/upload          # upload + extract zip/tar.gz
GET    /api/v1/workspaces/:id/archive/download?format= # download as zip/tar.gz

POST   /api/v1/workspaces/:id/reconcile               # force FS → DB sync
GET    /api/v1/workspaces/:id/stats                    # disk usage, file count
```

### Security

- Workspace access inherits from owner: if you can access the project/channel,
  you can access its workspace.
- Path traversal guard: all paths are cleaned and must resolve within the
  workspace root. Symlinks are rejected.
- File size limit: configurable per-workspace `max_bytes` with system default
  (`WORKSPACE_MAX_BYTES`, default 500MB).
- Archive extraction bomb protection: max files (10,000), max total extracted
  size (workspace quota), max single file (100MB).

### Migrations

- `xxx_workspace_tables.sql` (Postgres + SQLite): `workspaces`, `workspace_files`

### Checklist

- [ ] `models.Workspace`, `models.WorkspaceFile`, `models.WorkspacePatch` structs
- [ ] `WorkspaceStore` interface in `store/interfaces.go`
- [ ] Postgres implementation: `store/postgres/workspace.go`
- [ ] SQLite implementation: `store/sqlite/workspace.go`
- [ ] `WorkspaceFS` in new `server/workspace/` package
- [ ] Path traversal validation (must not escape workspace root)
- [ ] Archive extract (zip, tar.gz) with bomb protection
- [ ] Archive create (zip, tar.gz)
- [ ] MIME type detection on write (`net/http.DetectContentType` + extension fallback)
- [ ] Workspace CRUD handlers (6 endpoints)
- [ ] File CRUD handlers (5 endpoints)
- [ ] Archive handlers (2 endpoints)
- [ ] Reconcile + stats handlers (2 endpoints)
- [ ] `Stores.Workspaces` wired in `store/postgres/stores.go` + `store/sqlite/stores.go`
- [ ] Integration tests: workspace CRUD, file CRUD, archive round-trip, path traversal rejection
- [ ] PVC directory creation on startup (`/data/storage/workspaces/`)

---

## v0.21.1 — Workspace Tools + Channel/Project Binding

Make workspaces useful in chat mode. AI can operate on files through tool calls.
Channels and projects get workspace bindings.

### Tools (category: `workspace`)

**`workspace_ls`** — list files in workspace

```json
{
  "path": "src/",
  "recursive": false
}
```

Returns: array of `{ path, is_directory, content_type, size_bytes }`.

**`workspace_read`** — read a file

```json
{
  "path": "src/main.go"
}
```

Returns: file content as text (with truncation guard for large files, e.g. 50KB
soft limit with "file truncated" indicator). Binary files return a base64
summary or "binary file, N bytes" message.

**`workspace_write`** — create or overwrite a file

```json
{
  "path": "src/main.go",
  "content": "package main\n\nfunc main() {\n}\n"
}
```

Returns: confirmation with path and size. Creates parent directories
automatically.

**`workspace_rm`** — delete a file or directory

```json
{
  "path": "src/old_module/",
  "recursive": false
}
```

Returns: confirmation. Recursive required for non-empty directories.

**`workspace_mv`** — rename or move a file

```json
{
  "source": "src/old.go",
  "destination": "src/new.go"
}
```

**`workspace_patch`** — apply a text diff/patch to a file

```json
{
  "path": "src/main.go",
  "operations": [
    { "find": "oldFunction()", "replace": "newFunction()" },
    { "find": "// TODO: remove", "replace": "" }
  ]
}
```

The `find`/`replace` approach (same pattern as `str_replace` in many AI
coding tools) is more reliable for LLMs than unified diffs. Each operation's
`find` string must match exactly once in the file.

### Channel Workspace Binding

**Schema change:** `channels` table gains optional `workspace_id` FK.

**Behavior:**
- When a workspace is bound to a channel, workspace tools are injected into
  the tool set for that channel's completions (same pattern as KB tools via
  persona binding).
- New channel setting: "Workspace" toggle in channel settings.
- Creating a workspace from channel settings auto-binds it.

**Archive upload flow (chat mode):**
1. User uploads a zip/tar.gz to a channel with a workspace.
2. Upload handler detects archive MIME type + workspace binding.
3. Extracts into workspace (not attachment store).
4. Workspace tools become available for AI to operate on files.
5. User or AI can call archive download to get results.

Non-archive files still go to attachment store as before (backward compatible).

### Project Workspace Binding

**Schema change:** `projects` table gains optional `workspace_id` FK.

**Behavior:**
- Project detail panel gets a "Files" tab showing workspace file tree.
- All channels in a project inherit the project workspace (unless the channel
  has its own).
- Workspace resolution: channel workspace > project workspace (same override
  pattern as persona/KB resolution).

### Frontend

- Channel settings: workspace toggle, create/bind workspace.
- Project detail panel: Files tab with tree view (reusable component for
  editor surface later).
- Chat bar: workspace indicator when active (similar to KB indicator).

### Checklist

- [ ] `workspace_ls` tool implementation
- [ ] `workspace_read` tool with text truncation guard + binary detection
- [ ] `workspace_write` tool with auto-mkdir
- [ ] `workspace_rm` tool with recursive guard
- [ ] `workspace_mv` tool
- [ ] `workspace_patch` tool with find/replace operations
- [ ] Tool registration in `workspace` category
- [ ] Tool injection in completion handler when workspace bound
- [ ] `channels.workspace_id` column (migration, both dialects)
- [ ] `projects.workspace_id` column (migration, both dialects)
- [ ] Archive-to-workspace upload handler (detect archive + workspace → extract)
- [ ] Workspace resolution: channel → project fallback
- [ ] Channel settings UI: workspace toggle
- [ ] Project detail panel: Files tab
- [ ] Chat bar: workspace indicator
- [ ] Integration tests: tool execution, workspace resolution, archive upload flow
- [ ] Update `ExecutionContext` with workspace ID

---

## v0.21.2 — Workspace Indexing + Semantic Search

Embed text files in workspace for semantic search. Reuses the existing
`knowledge/` chunker and embedder — they're already decoupled from KB-specific
concerns.

### Data Model

**`workspace_chunks` table**

| Column | Type | Notes |
|--------|------|-------|
| `id` | UUID | PK |
| `workspace_id` | UUID | FK → workspaces |
| `file_id` | UUID | FK → workspace_files |
| `chunk_index` | INT | ordinal within file |
| `content` | TEXT | chunk text |
| `token_count` | INT | estimated |
| `embedding` | vector(3072) / JSON | pgvector or JSON text (SQLite) |
| `metadata` | JSONB / JSON | extensible: line_start, heading, etc. |

Index: pgvector IVFFlat on `embedding` (Postgres), app-level cosine (SQLite).
Index: `(file_id)` — re-index on file change.

### Indexing Pipeline

```
file write/upload
  → is text file? (same textMIMETypes + code extensions)
  → extract content (already in memory from write, or read from FS)
  → chunk (reuse knowledge.SplitText with configurable ChunkConfig)
  → embed (reuse knowledge.Embedder)
  → store in workspace_chunks (DELETE old chunks for file_id, INSERT new)
  → update workspace_files.sha256 (content-addressed skip on no-change)
```

**Code-aware MIME types** (extend `textMIMETypes`):

The existing KB ingester recognizes `text/plain`, `text/markdown`, `text/csv`,
`text/html`. For workspace indexing, we also recognize source code by extension:

```go
var indexableExtensions = map[string]bool{
    ".go": true, ".py": true, ".js": true, ".ts": true, ".jsx": true,
    ".tsx": true, ".rs": true, ".c": true, ".cpp": true, ".h": true,
    ".hpp": true, ".java": true, ".rb": true, ".php": true, ".swift": true,
    ".kt": true, ".scala": true, ".sh": true, ".bash": true, ".zsh": true,
    ".sql": true, ".yaml": true, ".yml": true, ".toml": true, ".json": true,
    ".xml": true, ".css": true, ".scss": true, ".less": true,
    ".md": true, ".txt": true, ".csv": true, ".html": true, ".htm": true,
    ".dockerfile": true, ".tf": true, ".hcl": true, ".proto": true,
    ".graphql": true, ".vue": true, ".svelte": true,
    ".pl": true, ".pm": true,  // Perl
    ".lua": true, ".zig": true, ".nim": true, ".ex": true, ".exs": true,
}
```

**Content-addressed skip:** if `workspace_files.sha256` matches the new write,
skip re-chunking and re-embedding. This makes bulk operations (archive extract)
efficient — only changed files get re-indexed.

**Background indexing:** file writes trigger async indexing (same goroutine
pattern as KB ingestion with semaphore). The write API returns immediately; the
`workspace_files` row gets an `index_status` column: `pending`, `indexing`,
`ready`, `error`, `skipped` (binary/non-text).

### Code-Aware Chunking

For source code, the default chunker works reasonably well but we add a
code-specific separator hierarchy:

```go
func CodeChunkConfig() ChunkConfig {
    return ChunkConfig{
        ChunkSize:    1500,    // larger chunks for code (functions can be long)
        ChunkOverlap: 200,
        Separators:   []string{"\n\nfunc ", "\n\nclass ", "\n\ndef ", "\n\n", "\n", " "},
    }
}
```

This is a simple heuristic — it splits on function/class boundaries when
possible, falling back to paragraph and line boundaries. It doesn't require
an AST parser and handles most languages well enough for search.

### Search Tool

**`workspace_search`** — semantic search across workspace files

```json
{
  "query": "database connection pooling",
  "top_k": 10,
  "file_pattern": "*.go"
}
```

Returns: array of `{ file_path, chunk_content, score, line_hint }`.

The `file_pattern` is optional glob filtering (applied post-search on the
`workspace_files.path` join). `line_hint` is approximate line number from
chunk metadata.

### Workspace Store Extensions

```go
// Added to WorkspaceStore interface
InsertChunks(ctx context.Context, chunks []models.WorkspaceChunk) error
DeleteChunksByFile(ctx context.Context, fileID string) error
SimilaritySearch(ctx context.Context, workspaceID string, embedding []float64, topK int) ([]models.WorkspaceChunkResult, error)
UpdateFileIndexStatus(ctx context.Context, fileID, status string) error
```

### `workspace_files` Schema Addition

| Column | Type | Notes |
|--------|------|-------|
| `index_status` | TEXT | `pending`, `indexing`, `ready`, `error`, `skipped` |
| `chunk_count` | INT | number of chunks after indexing |

### Indexing Configuration

- **Per-workspace toggle:** `workspaces.indexing_enabled` (default: `true`
  when embedding role is configured, `false` otherwise).
- **System setting:** `WORKSPACE_INDEXING_ENABLED` env var (global kill switch).
- **Concurrency:** shared semaphore with KB ingestion (don't overwhelm the
  embedding provider).

### Checklist

- [ ] `workspace_chunks` table (Postgres + SQLite migrations)
- [ ] `workspace_files.index_status` and `chunk_count` columns
- [ ] `WorkspaceChunk`, `WorkspaceChunkResult` model structs
- [ ] Store methods: `InsertChunks`, `DeleteChunksByFile`, `SimilaritySearch`, `UpdateFileIndexStatus`
- [ ] Postgres implementation with pgvector
- [ ] SQLite implementation with app-level cosine
- [ ] `workspace.Indexer` — reuses `knowledge.SplitText` + `knowledge.Embedder`
- [ ] Indexable type detection: MIME type + extension map
- [ ] Code-aware chunk config
- [ ] Content-addressed skip (sha256 check)
- [ ] Background indexing goroutine with semaphore
- [ ] `workspace_search` tool
- [ ] `workspace_search` glob filtering on file path
- [ ] Hook indexer into `WorkspaceFS.WriteFile` and `ExtractArchive`
- [ ] Workspace index status endpoint: `GET /api/v1/workspaces/:id/index-status`
- [ ] Integration tests: index pipeline, semantic search, content-addressed skip
- [ ] Notification on index complete/error (reuse notification service)

---

## v0.21.3 — Surface Infrastructure + REPL

Pure UI architecture. No workspace dependency. Can develop in parallel with
v0.21.0–v0.21.2 on the frontend side.

### Surface Registration API

Extends the existing `ctx.*` extension API from v0.11.0.

```js
Extensions.register({
  id: 'my-mode',
  init(ctx) {
    ctx.surfaces.register('my-surface', {
      label: 'My Mode',
      icon: 'code',          // lucide icon name
      regions: ['surface-main', 'sidebar-content'],
      activate() { /* take over regions */ },
      deactivate() { /* restore regions */ }
    });
  }
});
```

### Region Management

```js
ctx.ui.replace(regionId, element)  // saves current content, swaps in element
ctx.ui.restore(regionId)           // restores saved content
```

Regions are DOM containers identified by `data-surface-region` attributes.
`replace()` detaches the current children (preserved in memory, not destroyed),
inserts the new element. `restore()` re-attaches the saved children.

This is critical for CM6 — editor instances preserve state across mode switches
because the DOM nodes aren't destroyed, just detached.

### Surface Regions

```
┌──────────────────────────────────────────────────┐
│ [surface-header]                                  │
├──────────────┬───────────────────────────────────┤
│              │                                   │
│ [sidebar-    │  [surface-main]                   │
│  content]    │  (chat messages / editor /        │
│              │   article / custom)               │
│              │                                   │
│              ├───────────────────────────────────┤
│              │  [surface-footer]                 │
│              │  (chat input / editor toolbar)    │
└──────────────┴───────────────────────────────────┘
```

The sidebar-nav region (mode selector) is managed by the surface system itself,
not by individual extensions.

### Mode Selector

Appears in the sidebar below the brand logo, above chat history, when ≥1
extension surface is registered. Shows icon buttons for each mode. Chat is
always the first (default) mode.

```
  [💬] [</>] [📄]     ← mode selector (chat, editor, article)
  ──────────────
  Chat History...     ← sidebar-content (replaced per mode)
```

### Events

```js
Events.on('surface.activated', ({ surface, previous }) => { ... });
Events.on('surface.deactivated', ({ surface }) => { ... });
```

### REPL / Debug Console (#70)

Fourth tab in debug modal (Ctrl+Shift+L). See roadmap for full spec:

- `AsyncFunction` wrapper for top-level `await`
- Injected globals: `API`, `Events`, `Extensions`, `DebugLog`, `Surfaces`
- Pretty-print results (collapsible JSON, red errors with stack)
- Command history: ↑/↓ with `sessionStorage`
- Tab-completion on live object graphs
- Event label hints on `Events.publish('`/`Events.on('`
- Multi-line: Shift+Enter for newline, Enter to run
- Admin-gated OR `?debug=1` URL param

### Checklist

- [ ] `data-surface-region` attributes on index.html containers
- [ ] `surfaces.js` — SurfaceRegistry: register, activate, deactivate, getCurrent
- [ ] `ctx.ui.replace()` / `ctx.ui.restore()` with DOM preservation
- [ ] `ctx.surfaces.register()` API for extensions
- [ ] Mode selector component in sidebar
- [ ] Chat as default surface (implicit, always registered)
- [ ] `surface.activated` / `surface.deactivated` EventBus events
- [ ] REPL tab: AsyncFunction wrapper, global injection
- [ ] REPL tab: pretty-print results
- [ ] REPL tab: command history (sessionStorage)
- [ ] REPL tab: tab-completion on object graphs
- [ ] REPL tab: event label hints
- [ ] REPL tab: admin gate
- [ ] REPL tab: toolbar (clear, copy, help)
- [ ] Mobile: mode selector collapses to hamburger/bottom nav
- [ ] Integration with extension loader (surfaces from manifest)
- [ ] Documentation in EXTENSIONS.md §6 update

---

## v0.21.4 — Git Integration

Layer git operations onto workspace. A workspace can optionally track a git
remote. Credentials go through the vault.

### Schema Changes

**`workspaces` table additions:**

| Column | Type | Notes |
|--------|------|-------|
| `git_remote_url` | TEXT | nullable — HTTPS or SSH URL |
| `git_branch` | TEXT | nullable — default branch after clone |
| `git_credential_id` | UUID | nullable — FK to git_credentials |
| `git_last_sync` | TIMESTAMPTZ | nullable — last pull/push |

**`git_credentials` table:**

| Column | Type | Notes |
|--------|------|-------|
| `id` | UUID | PK |
| `user_id` | UUID | FK → users (owner) |
| `name` | TEXT | display name: "GitHub PAT", "GitLab token" |
| `auth_type` | TEXT | `https_pat`, `https_basic`, `ssh_key` |
| `encrypted_data` | BYTEA | AES-256-GCM (same vault pattern as BYOK) |
| `created_at` | TIMESTAMPTZ | |

Encrypted data contains: `{ "token": "..." }` for PAT, `{ "username": "...",
"password": "..." }` for basic, `{ "private_key": "...", "passphrase": "..." }`
for SSH.

### Git Operations (server-side)

Uses `os/exec` calling `git` binary (not a Go git library — keeps binary size
down and avoids CGO). The git binary is already in the Docker image for other
purposes.

```go
type GitOps struct {
    fs          *WorkspaceFS
    credentials CredentialResolver  // vault decryption
}

func (g *GitOps) Clone(ctx context.Context, w *models.Workspace, url, branch string, credID string) error
func (g *GitOps) Pull(ctx context.Context, w *models.Workspace) error
func (g *GitOps) Push(ctx context.Context, w *models.Workspace, message string) error
func (g *GitOps) Status(ctx context.Context, w *models.Workspace) (*GitStatus, error)
func (g *GitOps) Diff(ctx context.Context, w *models.Workspace, path string) (string, error)
func (g *GitOps) Commit(ctx context.Context, w *models.Workspace, message string, paths []string) error
func (g *GitOps) Log(ctx context.Context, w *models.Workspace, n int) ([]GitLogEntry, error)
func (g *GitOps) BranchList(ctx context.Context, w *models.Workspace) ([]string, string, error)
func (g *GitOps) Checkout(ctx context.Context, w *models.Workspace, branch string) error
```

Credential injection: temporary `.git-credentials` file or `GIT_ASKPASS` script
created for the duration of the operation, then securely wiped. SSH keys use
`GIT_SSH_COMMAND` with a temp key file.

### Git Tools (category: `workspace`)

**`git_status`** — show working tree status
**`git_diff`** — show diff for file or all changes
**`git_commit`** — stage and commit files
**`git_log`** — recent commit history
**`git_branch`** — list/switch branches

These are only injected when the workspace has `git_remote_url` set.

### API Endpoints

```
POST   /api/v1/workspaces/:id/git/clone     # { url, branch, credential_id }
POST   /api/v1/workspaces/:id/git/pull
POST   /api/v1/workspaces/:id/git/push
GET    /api/v1/workspaces/:id/git/status
GET    /api/v1/workspaces/:id/git/diff?path=
POST   /api/v1/workspaces/:id/git/commit     # { message, paths }
GET    /api/v1/workspaces/:id/git/log?n=
GET    /api/v1/workspaces/:id/git/branches
POST   /api/v1/workspaces/:id/git/checkout   # { branch }

# Credential management
POST   /api/v1/git-credentials               # create
GET    /api/v1/git-credentials               # list (user-scoped)
DELETE /api/v1/git-credentials/:id           # delete
```

### Post-Operation Hooks

After `clone`, `pull`, `checkout`: trigger workspace reconcile (sync FS → DB
index) and re-index changed files (v0.21.2). This ensures the file tree and
search index stay current after git operations.

### Frontend

- Workspace settings: git remote URL, credential picker, clone button.
- Git credential management in user Settings.
- Future (editor surface): git status indicators in file tree, commit UI.

### Checklist

- [ ] `git_credentials` table (Postgres + SQLite migrations)
- [ ] `workspaces` git columns (migration)
- [ ] `GitCredentialStore` interface + both implementations
- [ ] Vault integration for credential encryption/decryption
- [ ] `workspace.GitOps` with exec-based git operations
- [ ] Credential injection: temp `.git-credentials` / `GIT_SSH_COMMAND`
- [ ] Clone with depth option (shallow clone for large repos)
- [ ] Pull, push, status, diff, commit, log, branch, checkout
- [ ] Post-operation reconcile + re-index hook
- [ ] Git tool implementations (5 tools)
- [ ] Git API endpoints (9 endpoints)
- [ ] Credential CRUD endpoints (3 endpoints)
- [ ] Workspace settings UI: git config section
- [ ] User Settings: git credentials management
- [ ] Integration tests: clone, commit, push/pull cycle
- [ ] `.gitignore` respect in workspace indexing (skip ignored files)
- [ ] Security: reject `file://` and local path URLs in clone

---

## v0.21.5 — Editor Surface (Development Mode)

The IDE-like experience. Built entirely as a browser-tier extension consuming
workspace primitives from v0.21.0–v0.21.4 and surface infrastructure from
v0.21.3.

### Layout

```
┌──────────────────────────────────────────────────────┐
│ [surface-header]  workspace name | branch | status   │
├──────────────┬───────────────────┬───────────────────┤
│ File Tree    │  Code Editor      │  AI Chat Panel    │
│ (sidebar)    │  (CM6, main)      │  (resizable)      │
│              │                   │                   │
│  📁 src/     │  1│ package main  │  You: refactor    │
│    📄 main.go│  2│               │  the handler...   │
│    📄 util.go│  3│ func main() { │                   │
│  📁 tests/   │  4│   ...         │  AI: I'll update  │
│  📄 go.mod   │  5│ }             │  main.go...       │
│              │                   │                   │
├──────────────┴───────────────────┴───────────────────┤
│ [surface-footer]  file: src/main.go | Ln 4, Col 12  │
└──────────────────────────────────────────────────────┘
```

### Components

**File Tree** (sidebar-content region)
- Tree view backed by `workspace_ls` API (or cached from `Tree()`)
- File icons by extension/MIME type
- Click to open in editor
- Right-click context menu: rename, delete, new file, new folder
- Git status indicators (if git-enabled): modified, staged, untracked
- Drag-drop file reorder (within folders)

**Code Editor** (surface-main region)
- CM6 `codeEditor()` factory (already exists from v0.17.2)
- Language auto-detection from file extension
- Tab bar for multiple open files
- Modified indicator (dot on tab)
- Save: Ctrl/Cmd+S → `workspace_write` API
- Auto-save on tab switch / mode switch (configurable)

**AI Chat Panel** (split pane, resizable)
- Reuses the existing chat rendering pipeline
- Same channel context — conversation history carries over between modes
- Workspace tools auto-injected
- Tool call results update the editor live (if the modified file is open)

**Status Bar** (surface-footer region)
- Current file path
- Cursor position (line, column)
- Language mode
- Encoding
- Git branch (if applicable)

### Extension Manifest

```json
{
  "id": "editor-mode",
  "name": "Development",
  "version": "1.0.0",
  "type": "browser",
  "surfaces": [{
    "id": "editor",
    "label": "Editor",
    "icon": "code-2",
    "regions": ["surface-main", "surface-footer", "sidebar-content", "surface-header"]
  }],
  "permissions": ["workspace"]
}
```

### Live Update on Tool Calls

When the AI calls `workspace_write` or `workspace_patch` and the target file
is open in the editor, the editor content updates live. Implementation:

1. Tool call completes → workspace write handler fires EventBus event
   `workspace.file.changed` with `{ workspaceId, path }`.
2. Editor surface subscribes to this event.
3. On match (file is open), fetch fresh content from API and update CM6
   state via `view.dispatch({ changes })`.

### Checklist

- [ ] `editor-mode` extension directory structure
- [ ] File tree component (tree view, icons, context menu)
- [ ] Tab bar component (open files, modified indicator)
- [ ] Split pane layout (editor + chat, resizable divider)
- [ ] CM6 editor integration with language detection
- [ ] Save flow: Ctrl/Cmd+S → API → DB index update
- [ ] Auto-save on tab/mode switch
- [ ] Live update on `workspace.file.changed` event
- [ ] Status bar: file, cursor, language, branch
- [ ] Surface registration via manifest
- [ ] Git status indicators in file tree (if v0.21.4 landed)
- [ ] Mobile: single-pane mode (editor or chat, toggle)
- [ ] Keyboard shortcuts: Ctrl+P (quick open), Ctrl+Shift+F (workspace search)
- [ ] Quick open: fuzzy file finder using `workspace_files` index

---

## v0.21.6 — Article Surface + Document Output Pipeline

Writing-focused surface. The conversation is secondary — the document is the
artifact.

### Document Output Pipeline

Before article mode, we need a way for extensions to produce downloadable
output. This is the pipeline:

```
extension generates content
  → POST /api/v1/workspaces/:id/files/write (save to workspace)
  → or POST /api/v1/workspaces/:id/export (convert + save)
  → user downloads from workspace or gets direct download link
```

Export endpoint supports format conversion (markdown → HTML, markdown → PDF via
pandoc if available, markdown → DOCX). This is a stretch goal — initial version
just saves to workspace and lets users download the raw file.

### Layout

```
┌──────────────────────────────────────────────────────┐
│ [surface-header]  Document Title    [Export ▾]       │
├──────────────┬───────────────────────────────────────┤
│ Outline      │  Rich Text Editor (CM6 markdown)      │
│              │                                       │
│  § Intro     │  # My Article                         │
│  § Methods   │                                       │
│    § Data    │  Compelling introduction paragraph     │
│    § Analysis│  about the topic at hand...            │
│  § Results   │                                       │
│  § Discussion│  ## Methods                            │
│              │                                       │
│──────────────│  ### Data Collection                   │
│ AI Assistant │                                       │
│              │  We gathered data from...              │
│ "Expand the  │                                       │
│  methods     │                                       │
│  section..." │                                       │
├──────────────┴───────────────────────────────────────┤
│ [surface-footer]  Words: 1,234 | Reading: ~5 min     │
└──────────────────────────────────────────────────────┘
```

### Components

**Outline** (sidebar-content, top section)
- Auto-generated from heading structure in document
- Click to scroll to section
- Drag to reorder sections

**AI Assistant** (sidebar-content, bottom section)
- Lightweight chat interface for document-focused prompts
- Tools: `workspace_read`, `workspace_write`, `workspace_search`
- Additional article tools:
  - `suggest_outline` — propose structure for a topic
  - `expand_section` — flesh out a heading with content
  - `check_citations` — verify URLs are reachable (via url_fetch)

**Rich Text Editor** (surface-main)
- CM6 `noteEditor()` factory (from v0.17.3) with enhanced live preview
- Heading decorations, blockquotes, code blocks, links
- Focus mode: dim everything except current section

**Export** (surface-header dropdown)
- Download as Markdown (.md)
- Download as HTML (rendered)
- Download as PDF (if pandoc available)
- Copy to clipboard (markdown)

### Checklist

- [ ] `article-mode` extension directory structure
- [ ] Outline component (auto-generated from headings, click-to-scroll)
- [ ] Sidebar split: outline (top) + AI assistant (bottom)
- [ ] Rich text editor with enhanced markdown live preview
- [ ] Export dropdown: markdown, HTML, PDF
- [ ] Article-specific tools: `suggest_outline`, `expand_section`
- [ ] Focus mode (dim non-active sections)
- [ ] Word count + reading time in status bar
- [ ] Surface registration via manifest
- [ ] Auto-save document to workspace
- [ ] Mobile: outline collapses to top dropdown

---

## Cross-Cutting Concerns

### Migration Strategy

Each sub-release gets its own migration file(s), both Postgres and SQLite.
Migrations run on backend startup (existing pattern). Numbering continues
from v0.20.0's last migration.

### Test Strategy

- Backend integration tests against both Postgres and SQLite for every store
  method and handler (existing CI matrix pattern).
- Workspace FS tests: use a temp directory, not the real PVC.
- Tool execution tests: mock workspace with pre-populated files.
- Surface tests: manual testing + REPL verification (surface infrastructure
  is frontend-only, no backend tests).

### Backward Compatibility

- Channels without workspaces work exactly as before.
- Projects without workspaces work exactly as before.
- Archive uploads to channels without workspaces go to attachment store.
- Workspace tools only appear when a workspace is bound.

### Documentation Updates

Each sub-release updates:
- `VERSION` → `0.21.N`
- `CHANGELOG.md` — detailed entry
- `ARCHITECTURE.md` — workspace section, surface system section
- `EXTENSIONS.md` — §6 update for surface implementation
- `ROADMAP.md` — mark completed items

### Deployment

- PVC: ensure `workspaces/` directory is created at startup
  (same pattern as `attachments/` directory creation).
- Git binary: verify `git` is in the Docker image (add to Dockerfile
  if not present).
- Embedding role: workspace indexing gracefully degrades when no embedding
  model is configured (files still work, search doesn't).
- Quota defaults: `WORKSPACE_MAX_BYTES=524288000` (500MB),
  `WORKSPACE_MAX_FILES=10000`.