# OpenCode Session Internals

This document contains findings about how OpenCode manages sessions, based on direct database investigation. Use this when debugging session-related issues in kugetsu.

## Database Location

```bash
opencode db path
# Returns: ~/.local/share/opencode/opencode.db
```

## Session Table Schema

```sql
CREATE TABLE `session` (
    `id` text PRIMARY KEY,
    `project_id` text NOT NULL,
    `parent_id` text,                    -- Parent session ID (for forked sessions)
    `slug` text NOT NULL,                -- Auto-generated adjective-animal name
    `directory` text NOT NULL,            -- Working directory for session
    `title` text NOT NULL,
    `version` text NOT NULL,
    `share_url` text,
    `summary_additions` integer,
    `summary_deletions` integer,
    `summary_files` integer,
    `summary_diffs` text,
    `revert` text,
    `permission` text,                    -- JSON array of permission rules
    `time_created` integer NOT NULL,      -- Unix timestamp in milliseconds
    `time_updated` integer NOT NULL,
    `time_compacting` integer,
    `time_archived` integer,
    `workspace_id` text
);
```

## Session ID Format

OpenCode session IDs follow the format: `ses_<base62_chars>`

Example: `ses_2b4eb7afbffezJwifgucdLRkt8`

The ID appears to be generated using a timestamp-based algorithm with random components. Analysis of 118+ sessions shows:

- **No duplicate IDs** - Each session gets a unique ID even with concurrent forks
- **No sequential patterns** - IDs are not sequential even for sessions created milliseconds apart
- **Contains timestamp** - The first numeric portion appears to encode creation time

## Querying Sessions

### List all sessions

```bash
opencode session list
```

### Query database directly (requires sqlite3 or python)

```python
import sqlite3
conn = sqlite3.connect('/home/shoko/.local/share/opencode/opencode.db')
cursor = conn.cursor()

# Get all sessions
cursor.execute('SELECT id, parent_id, slug, directory FROM session')

# Get forked sessions (sessions with a parent)
cursor.execute('SELECT id, parent_id FROM session WHERE parent_id IS NOT NULL')

# Get sessions by directory
cursor.execute("SELECT id, slug FROM session WHERE directory LIKE '%kugetsu%'")
```

## Session Relationships

### Parent-Child Relationships

When you run `opencode run --fork --session <parent_id>`, OpenCode:

1. Creates a NEW session with a unique ID
2. Sets the `parent_id` field to reference the parent session
3. The child session inherits context from parent but has its own workspace

### Session Detection in Kugetsu

Kugetsu uses `opencode session list` to detect newly created sessions. The output format is:

```
ses_abc123def456
ses_xyz789...
```

Kugetsu's `cmd_start` workflow:

1. **Before fork**: List all sessions, store in array
2. **Fork**: Run `opencode run --fork --session <parent>`
3. **After fork**: List sessions again
4. **Detect new**: Compare before/after arrays, exclude known sessions (base, pm-agent)

```bash
# Store before sessions in array
declare -a before_sessions=()
while IFS= read -r sess; do
    before_sessions+=("$sess")
done < <(opencode session list 2>/dev/null | grep -oP '^ses_\w+')

# Fork happens here...

# Find sessions not in before array
while IFS= read -r sess; do
    # Skip base and pm-agent sessions
    [ "$sess" = "$base_session_id"" ] && continue
    [ "$sess" = "$pm_agent_session_id" ] && continue
    
    # Check if session existed before
    local existed_before=false
    for before_sess in "${before_sessions[@]}"; do
        if [ "$sess" = "$before_sess" ]; then
            existed_before=true
            break
        fi
    done
    
    if [ "$existed_before" = false ]; then
        new_session_id="$sess"
        break
    fi
done < <(opencode session list 2>/dev/null | grep -oP '^ses_\w+')
```

## Session Directories

Each session has a `directory` field indicating its working directory:

| Directory | Purpose |
|-----------|---------|
| `/home/shoko` | Base session, PM agent |
| `/home/shoko/repositories/kugetsu` | Project sessions |
| `~/.kugetsu/worktrees/<issue-ref>` | Per-issue worktrees |

## Permissions

Sessions have a `permission` field containing a JSON array:

```json
[
  {"permission": "question", "pattern": "*", "action": "deny"},
  {"permission": "plan_enter", "pattern": "*", "action": "deny"},
  {"permission": "plan_exit", "pattern": "*", "action": "deny"},
  {"permission": "external_directory", "pattern": "*", "action": "allow"}
]
```

### Common Permission Issues

**Issue**: `permission requested: external_directory (/path/*); auto-rejecting`

**Cause**: The session's `permission` field may be `NULL` or missing required rules.

**Fix**: Update via SQLite:

```python
import sqlite3
conn = sqlite3.connect('/home/shoko/.local/share/opencode/opencode.db')
cursor = conn.cursor()

PERMISSION_JSON = '[{"permission":"question","pattern":"*","action":"deny"},{"permission":"plan_enter","pattern":"*","action":"deny"},{"permission":"plan_exit","pattern":"*","action":"deny"},{"permission":"external_directory","pattern":"*","action":"allow"}]'

cursor.execute("UPDATE session SET permission = ? WHERE id = ?", 
               (PERMISSION_JSON, session_id))
conn.commit()
```

## Known Issues & Solutions

### Session ID Collision (Issue #81)

**Problem**: Forked sessions showing same ID as PM agent.

**Investigation Results**: 
- OpenCode does NOT generate duplicate IDs (verified with 118+ sessions)
- Database shows unique IDs even for concurrent forks
- Issue is in kugetsu's session detection logic, not opencode

**Solution**: Use array-based session detection (see above) instead of string/regex matching.

### Stale Permission NULL (Issue #36)

**Problem**: PM agent cannot access directories despite permissions.

**Root Cause**: Session created with `permission = NULL` in database.

**Detection**:
```python
cursor.execute("SELECT id FROM session WHERE permission IS NULL")
```

**Fix**: Set permissions via kugetsu:
```bash
kugetsu doctor --fix-permissions
```

## Useful Queries

### Find sessions by issue reference

```python
# Find sessions for a specific issue worktree
cursor.execute("SELECT id, slug FROM session WHERE directory LIKE '%issue-81%'")
```

### Find orphaned sessions (no parent, old)

```python
import time
old_threshold = time.time() - (30 * 24 * 60 * 60)  # 30 days ago

cursor.execute("""SELECT id, slug, directory, time_created 
                 FROM session 
                 WHERE parent_id IS NULL 
                 AND time_created < ?
                 ORDER BY time_created""", (old_threshold * 1000,))
```

### Count sessions per project

```python
cursor.execute("""SELECT project_id, COUNT(*) as cnt 
                 FROM session 
                 GROUP BY project_id 
                 ORDER BY cnt DESC""")
```

## Debugging Tips

1. **Check current sessions**: `opencode session list`
2. **Check database**: `opencode db "SELECT id, parent_id, slug FROM session ORDER BY time_created DESC LIMIT 10"`
3. **Verify permissions**: Check if `permission` field is NULL or valid JSON
4. **Check directory**: Ensure session directory exists and is accessible
5. **Compare before/after**: When debugging detection, log both before and after session lists

## External References

- OpenCode Repository: https://github.com/opencode-ai/opencode
- Session Management: Uses SQLite with unique constraint on `id` column
- Fork Operation: Sets `parent_id` to establish relationship