docs: Add agentic workflow playbook for camera_android_camerax

packages/camera/camera_android_camerax/.agents/playbook.md

@@ -0,0 +1,52 @@
+# Playbook: One-Shot Agentic Development Workflow
+
+This playbook outlines the recommended workflow for humans to orchestrate agent-driven feature development. It is structured into two main phases: **Planning & Consensus** and **Phased Execution & Validation**.
+
+```mermaid
+graph TD
+    A[Start: Define Feature/Issue] --> B[Phase 1: Generate Execution Plan]
+    B --> C[Commit Plan & Open PR]
+    C --> D[Peer Code Review & Comments]
+    D -->|Comments Added| E[Agent Updates Plan in PR]
+    E --> D
+    D -->|Approved| F[Phase 2: Environment Setup & Verification]
+    F --> G[Run One-Shot Execution Flow]
+    G --> H[Complete: Ready for final PR approval]
+```
+
+---
+
+## Phase 1: Planning & Consensus
+
+The planning phase ensures the agent and human stakeholders align on the technical design and scope before any implementation begins.
+
+### 1. Generating the Plan
+* **Action:** Prompt the agent to analyze the requirements and write a detailed execution plan (`plan.md` or similar design artifact).
+* **Tooling:** You can recommend the `/plan` or `/grill-me` slash commands to help generate and refine the plan iteratively.
+
+### 2. PR-Based Consensus Loop
+To gather consensus across multiple technical voices/reviewers:
+1. **Commit and Push:** Commit the plan artifact to a git branch and open a Pull Request (PR).
+2. **Review:** Human reviewers add comments directly on the plan in the PR.
+3. **Iterative Updates:** The agent is responsible for reading the PR comments and updating the plan until all comments are addressed and the plan is approved.
+
+> [!NOTE]
+> Utilizing PRs for plan review is the most effective mechanism for achieving consensus on design decisions before modifying production code.
+
+---
+
+## Phase 2: Execution & Validation
+
+Once the plan is approved, the workflow transitions to the execution phase.
+
+### 1. Environment Verification
+Before execution begins, the agent must validate that the environment is fully set up and in a clean, working state.
+* **Pre-Flight Checks:** Run the repository diagnostics or readiness checks (such as the `check-readiness` skill) to verify toolchain versions, environment variables, and SDK configurations.
+* **Clean State Check:** Run static analysis and basic tests on the unmodified branch to confirm that any existing failures are identified beforehand.
+
+### 2. One-Shot Execution Flow
+In this phase, the agent executes the approved plan using a specialized one-shot execution skill or subagent context.
+
+At a high level, this execution flow focuses on:
+1. **Targeted Code Modification:** Editing the codebase strictly within the bounds of the approved plan.
+2. **Verification & Testing:** Running automated validation (linters, formatters, and unit/integration tests) to ensure the change functions correctly and does not introduce regressions.