docs: add testing requirements to AGENTS.md

- Add Testing Requirements section with explicit test-before-commit rule
- Fix project type reference (FastAPI -> Flutter)

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

AGENTS.md

@@ -6,7 +6,7 @@ This document contains instructions and documentation references for AI assistan
 # AGENTS.md
 
 > **Start every session by reading this file.**
-> This file outlines the operational protocols, coding standards, and architectural decisions for this FastAPI project.
+> This file outlines the operational protocols, coding standards, and architectural decisions for this Flutter project.
 
 ## 1. Agent Operational Protocols
 
@@ -39,6 +39,13 @@ This document contains instructions and documentation references for AI assistan
     * `refactor: split monolith dependency file`
 * **Atomic Commits:** Keep commits small. One logical change = one commit.
 
+### 🧪 Testing Requirements
+* **Always add tests for new code before committing.** No exceptions.
+* Tests should cover the happy path and key edge cases.
+* Run `flutter test` before committing to ensure all tests pass.
+* For widgets: use widget tests. For business logic: use unit tests.
+* Code coverage should not decrease with new commits.
+
 ### 📝 Changelog Maintenance
 * **Update `CHANGELOG.md`** with every user-facing change.
 * Format: `## [Unreleased] - YYYY-MM-DD` followed by `### Added`, `### Changed`, or `### Fixed`.