Docs: Model steering and plan mode guide

docs/cli/tutorials/plan-mode-steering.md

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+# Use Plan Mode with model steering for complex tasks
+
+Architecting a complex solution requires precision. By combining Plan Mode's
+structured environment with model steering's real-time feedback, you can guide
+Gemini CLI through the research and design phases to ensure the final
+implementation plan is exactly what you need.
+
+> **Note:** This is a preview feature currently under active development. As of
+> March 4, 2026, Plan Mode is only available on the preview channel.
+
+## Prerequisites
+
+- Gemini CLI installed and authenticated.
+- [Plan Mode](../plan-mode.md) enabled in your settings.
+- [Model steering](../model-steering.md) enabled in your settings.
+
+## Why combine Plan Mode and model steering?
+
+[Plan Mode](../plan-mode.md) typically follows a linear path: research, propose,
+and draft. Adding model steering lets you:
+
+1.  **Direct the research:** Correct the agent if it's looking in the wrong
+    directory or missing a key dependency.
+2.  **Iterate mid-draft:** Suggest a different architectural pattern while the
+    agent is still writing the plan.
+3.  **Speed up the loop:** Avoid waiting for a full research turn to finish
+    before providing critical context.
+
+## Step 1: Start a complex task
+
+Enter Plan Mode and start a task that requires research.
+
+**Prompt:** `/plan I want to implement a new notification service using Redis.`
+
+Gemini CLI enters Plan Mode and starts researching your existing codebase to
+identify where the new service should live.
+
+## Step 2: Steer the research phase
+
+As you see the agent calling tools like `list_directory` or `grep_search`, you
+might realize it's missing the relevant context.
+
+**Action:** While the spinner is active, type your hint:
+`"Don't forget to check packages/common/queues for the existing Redis config."`
+
+**Result:** Gemini CLI acknowledges your hint and immediately incorporates it
+into its research. You'll see it start exploring the directory you suggested in
+its very next turn.
+
+## Step 3: Refine the design mid-turn
+
+After research, the agent starts drafting the implementation plan. If you notice
+it's proposing a design that doesn't align with your goals, steer it.
+
+**Action:** Type:
+`"Actually, let's use a Publisher/Subscriber pattern instead of a simple queue for this service."`
+
+**Result:** The agent stops drafting the current version of the plan,
+re-evaluates the design based on your feedback, and starts a new draft that uses
+the Pub/Sub pattern.
+
+## Step 4: Approve and implement
+
+Once the agent has used your hints to craft the perfect plan, review the final
+`.md` file.
+
+**Action:** Type: `"Looks perfect. Let's start the implementation."`
+
+Gemini CLI exits Plan Mode and transitions to the implementation phase. Because
+the plan was refined in real-time with your feedback, the agent can now execute
+each step with higher confidence and fewer errors.
+
+## Tips for effective steering
+
+- **Be specific:** Instead of "do it differently," try "use the existing
+  `Logger` class in `src/utils`."
+- **Steer early:** Providing feedback during the research phase is more
+  efficient than waiting for the final plan to be drafted.
+- **Use for context:** Steering is a great way to provide knowledge that might
+  not be obvious from reading the code (e.g., "We are planning to deprecate this
+  module next month").
+
+## Next steps
+
+- Explore [Agent Skills](../skills.md) to add specialized expertise to your
+  planning turns.
+- See the [Model steering reference](../model-steering.md) for technical
+  details.