Agent Mode

SideCar isn’t just a chatbot — it’s an autonomous coding agent. It can read your code, edit files, run tests, diagnose errors, and iterate until the task is done.

The agent loop

When you give SideCar a task, it enters an agent loop:

1. Read — examines relevant files, diagnostics, and context
2. Plan — decides which tools to use
3. Execute — writes/edits files, runs commands
4. Verify — checks diagnostics and test results
5. Iterate — if something failed, goes back to step 1

The loop continues until the task is complete, the model returns a final response, or safety limits are reached.

Approval modes

Control how much autonomy SideCar has via the agent mode dropdown in the chat header, or the sidecar.agentMode setting:

Mode	Reads	Writes	Destructive
Cautious (default)	Auto-approve	Confirm	Confirm
Autonomous	Auto-approve	Auto-approve	Confirm
Manual	Confirm	Confirm	Confirm

• Cautious is recommended for most use. File reads happen automatically; writes and edits show a diff preview for your approval.
• Autonomous lets SideCar work without interruption. Use for trusted tasks where you’ll review changes after.
• Manual requires approval for every tool call, including file reads.

Safety guardrails

Setting	Default	Description
sidecar.agentMaxIterations	25	Max loop iterations before auto-stop
sidecar.agentMaxTokens	100000	Max total tokens before auto-stop

The Stop button (the Send button toggles to a red Stop during processing) lets you abort at any time. Partial changes can be reverted with Undo.

Built-in tools

SideCar has 10+ built-in tools the agent can use:

Tool	Description
read_file	Read file contents
write_file	Create or overwrite files
edit_file	Search/replace edits in existing files
search_files	Glob pattern file search
grep	Content search with regex
run_command	Execute shell commands
list_directory	List directory contents
get_diagnostics	Read compiler errors, warnings, and security findings
run_tests	Run test suites with auto-detection
spawn_agent	Spawn parallel sub-agents for complex tasks
git_status	Show working tree status
git_stage	Stage files for commit
git_commit	Create a commit
git_log	View commit history
git_push	Push to remote
git_pull	Pull from remote
git_branch	Create/switch/list branches
git_stash	Stash/pop changes
git_diff	Show file diffs

Additional tools can be added via MCP servers and custom tools.

Tool permissions

Override the approval behavior for specific tools:

"sidecar.toolPermissions": {
  "run_command": "ask",
  "read_file": "allow",
  "write_file": "deny"
}

Values: "allow" (always run), "deny" (always block), "ask" (always confirm). Per-tool permissions override the agent mode.

Diff preview

In cautious mode, write_file and edit_file open VS Code’s built-in diff editor showing the proposed changes side-by-side with the original. You accept or reject via an inline confirmation card.

Undo / rollback

SideCar snapshots every file before modifying it. To revert all changes:

• Press Cmd+Shift+U / Ctrl+Shift+U
• Or type /undo in the chat

After an agent run, a change summary panel shows all modified files with inline diffs. You can revert individual files or accept all changes.

Plan mode

Enable sidecar.planMode to have SideCar generate a plan before executing any tools. You review and approve the plan, then SideCar executes it. Useful for complex tasks where you want to validate the approach first.

Thinking / reasoning

Models that support reasoning output show their thinking in collapsible “Reasoning” blocks:

• Anthropic API: Extended thinking blocks stream automatically
• Ollama models: <think>...</think> tags (used by qwen3, deepseek-r1) are parsed and displayed as reasoning blocks

Set sidecar.expandThinking to true to show reasoning blocks expanded by default.

Verbose mode

Enable sidecar.verboseMode or type /verbose to see detailed agent internals:

• System prompt — the full assembled prompt shown at the start of each run
• Iteration summaries — elapsed time and token counts per iteration
• Tool selection — which tool was chosen and why

Verbose output appears in yellow-bordered collapsible blocks. Use /prompt to inspect the system prompt at any time.

Progress indicators

During agent runs, the UI shows:

• Step count and max iterations
• Elapsed time
• Token usage
• Animated progress bar and tool execution pulses