chore(diff): update doc

Author: chuan2984

DIFF_FEATURE.md

@@ -11,17 +11,19 @@ vim.g.opencode_opts = {
   events = {
     session_diff = {
       enabled = true,  -- PR-style review (default: true)
+      open_in_tab = false,  -- Open review in tab instead of vsplit(default: false)
     },
   },
 }
 ```
 
 **To disable:**
+
 ```lua
 vim.g.opencode_opts = {
   events = {
     session_diff = {
-      enabled = false,  -- Disable diff review
+      enabled = false,
     },
   },
 }
@@ -31,7 +33,7 @@ vim.g.opencode_opts = {
 
 1. **AI makes edits** across multiple files
 2. **Files are written** to disk immediately
-3. **`session.diff` event fires** with complete change data:
+3. **`message.updated` event fires** with complete change data:
    - All modified files in one event
    - Each file includes `before` (original) and `after` (new) content
 4. **Review UI opens** showing current file's changes
@@ -45,63 +47,45 @@ vim.g.opencode_opts = {
    - `q` - Close review (keeps current state)
 
 **Restore Strategy:**
-- Uses `before` content from `session.diff` event
-- Writes original content back to disk
-- Reloads buffer if open in editor
-- No Git dependencies required
-   - `A` - Accept all files
-   - `R` - Reject all files
-   - `q` - Close review (keeps current state)
 
-**Restore Strategy:**
-- Uses `before` content from `session.diff` event
+- Uses `before` content from `messaged.updated` event
 - Writes original content back to disk
 - Reloads buffer if open in editor
 - No Git dependencies required
-
-### Permission-Based Review
-
-1. **AI wants to edit file** → Permission request fires
-2. **Shows unified diff** in vertical split
-3. **User decides:**
-   - `<leader>aa` - Accept edit (file will be written)
-   - `<leader>ar` or `q` - Reject edit (file won't be modified)
-4. **Repeat for each file** individually
+  - `A` - Accept all files
+  - `R` - Reject all files
+  - `q` - Close review (keeps current state)
 
 ## Usage Example
 
 ### Testing Session Diff Review
 
 1. **Enable the feature** (it's on by default)
 2. **Ask OpenCode to make changes:**
+
    ```
    Update file1.txt and file2.txt with programming jokes
    ```
+
 3. **Wait for OpenCode to finish**
 4. **Review UI appears** showing all changes
 5. **Navigate with `n`/`p`**, accept with `a`, or reject with `r`
 
 ## Files
 
 **Core Implementation:**
-- `plugin/events/session_diff.lua` - Listens for `OpencodeEvent:session.diff`
-- `lua/opencode/diff.lua` - Review UI and restore logic
-- `lua/opencode/config.lua` - Configuration options
-- `lua/opencode/events.lua` - Type definitions
 
-**Legacy (kept for compatibility):**
-- `plugin/events/permissions.lua` - Permission-based review (disabled by default)
+- `plugin/events/session_diff.lua` - Listens for `OpencodeEvent:message.updated`
+- `lua/opencode/diff.lua` - Review UI and restore logic
 
 ## Current Limitations
 
-1. **Simple diff display** - Shows before/after content, not unified diff format (yet)
-2. **No syntax highlighting** - Displays as plain diff format
+1. **Simple diff display** - Shows before/after content using vim.diff(unified)
 3. **No per-hunk review** - Accept/reject entire file only
-4. **Buffer management** - Opens in vertical split (not configurable yet)
 
 ## Future Enhancements
 
-- [ ] Proper unified diff rendering with syntax highlighting
+- [x] Proper unified diff rendering with syntax highlighting
 - [ ] Per-hunk accept/reject
 - [ ] Floating window option
 - [ ] Side-by-side diff view
@@ -115,19 +99,17 @@ vim.g.opencode_opts = {
 ### Event Flow
 
 ```
-AI makes edits
-    ↓
-Files written to disk
-    ↓
-OpencodeEvent:session.diff fires
-    ↓
-plugin/events/session_diff.lua catches it
-    ↓
-lua/opencode/diff.lua handles review
-    ↓
-User reviews in split buffer
-    ↓
-Accept (keep) or Reject (restore from 'before' content)
+ → session.created
+  → message.updated (user)
+  → session.status (busy)
+  → message.updated (assistant starts)
+  → message.part.updated (streaming response)
+  → [4x tool calls executed, files edited]
+  → message.updated (finish: "tool-calls")
+  → session.diff (ONE event with all cumulative changes in the session)
+  → message.updated (Using this as the indicator for a Q&A cycle, only contains diff for files
+  changed, not like session.diff that contains everything)
+  → session.status (idle)
 ```
 
 ### Restore Strategy
@@ -151,22 +133,3 @@ Instead of Git stash/commit, we use the `before` content from the event:
 -- To revert:
 vim.fn.writefile(vim.split(file_data.before, "\n"), file_data.file)
 ```
-
-**Benefits:**
-- No Git dependency
-- No pollution of Git history
-- 100% accurate (exact original content)
-- Works in any project
-
-## Comparison: Permission vs Session Diff
-
-| Aspect | Permission Review | Session Diff Review |
-|--------|------------------|---------------------|
-| **Timing** | Before file write | After file write |
-| **Unified view** | ❌ One file at a time | ✅ All files together |
-| **Navigation** | ❌ Sequential only | ✅ Free navigation |
-| **Configuration** | Needs OpenCode config | Works out of the box |
-| **Undo method** | Don't write file | Restore from `before` |
-| **Reliability** | ⚠️ Works sometimes | ✅ Always works |
-
-**Recommendation:** Use Session Diff Review for better UX.