diff --git a/.agents/AGENTS.md b/.agents/AGENTS.md
new file mode 100644
index 000000000..a7cc72d92
--- /dev/null
+++ b/.agents/AGENTS.md
@@ -0,0 +1,11 @@
+# Custom Rules for AI Coding Assistants
+
+To ensure all agentic tasks in this repository are executed as accurately, securely, and token-efficiently as possible, you must strictly follow these rules:
+
+## 1. Tool Selection & Efficiency
+* **Prefer Domain-Specific MCP Tools:** Before running generic terminal commands (e.g. `grep`, `find`, or compiler check scripts), always check if a domain-specific MCP tool (such as `lsp`, `analyze_files`, or `rip_grep_packages` from `dart-mcp-server`) is available and use it instead.
+* **Limit Command Output:** Any command-line tool execution (`run_command`) that might print large datasets, build logs, or file listings must have its stdout restricted using filters or limits (e.g. `head -n 50`, `git log -n 5`) to prevent context bloat.
+* **Targeted File Reading:** When reading source files, specify precise line boundaries with `StartLine` and `EndLine` parameters in `view_file` to read only the code you need. Avoid loading entire files over 100 lines.
+
+## 2. Task Delegation & Subagents
+* **Isolate Exploratory Research:** For open-ended research, codebase discovery, or scanning third-party docs, delegate the subtask to the `research` subagent. The subagent will run in a separate workspace context and return a concise summary, keeping the main conversation's history clean and token-efficient.
diff --git a/.claudeignore b/.claudeignore
new file mode 100644
index 000000000..788b7362f
--- /dev/null
+++ b/.claudeignore
@@ -0,0 +1,9 @@
+# Exclude baseline output logs and reports from AI scanning
+third_party/tool/baseline/
+**/build/reports/
+**/build/test-results/
+
+# Exclude large test fixture mock directories
+**/testData/
+**/sample_tests/
+
diff --git a/.geminiignore b/.geminiignore
new file mode 100644
index 000000000..788b7362f
--- /dev/null
+++ b/.geminiignore
@@ -0,0 +1,9 @@
+# Exclude baseline output logs and reports from AI scanning
+third_party/tool/baseline/
+**/build/reports/
+**/build/test-results/
+
+# Exclude large test fixture mock directories
+**/testData/
+**/sample_tests/
+
diff --git a/.github/workflows/presubmit.yaml b/.github/workflows/presubmit.yaml
index 025053edf..1d9033560 100644
--- a/.github/workflows/presubmit.yaml
+++ b/.github/workflows/presubmit.yaml
@@ -12,15 +12,15 @@ permissions:
   contents: read
 
 jobs:
-  # Job 0: Check Agent Skills Documentation
-  check-skills-docs:
+  # Job 0: Validate Agent Configurations
+  validate-agent-configs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout code
         uses: actions/checkout@v6
 
-      - name: Run documentation check
-        run: ./tool/check_agent_skills.sh
+      - name: Run configurations check
+        run: ./tool/validate_agent_configs.sh
 
   # Job 1: Build Plugin
   build-plugin:
diff --git a/.gitignore b/.gitignore
index c8fc18583..13e4b843b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,20 @@
 # Mac Finder settings
 .DS_Store
 
+
+# IntelliJ and IDEs
+.idea/
+**/.idea/
+*.iml
+third_party/.settings/
 /.vscode
+
+# Gradle
+.gradle/
+**/build/
+out/
+
+# Dart / Flutter
+.dart_tool/
+.packages
+pubspec.lock
diff --git a/tool/check_agent_skills.sh b/tool/validate_agent_configs.sh
similarity index 68%
rename from tool/check_agent_skills.sh
rename to tool/validate_agent_configs.sh
index 3e2bcd780..0b30f56d0 100755
--- a/tool/check_agent_skills.sh
+++ b/tool/validate_agent_configs.sh
@@ -41,6 +41,23 @@ for link in $(grep -o '\.agents/skills/[a-zA-Z0-9_-]*/SKILL.md' "$README_FILE" |
     exit_code=1
   fi
 done
+# 3. Check that ignore files (.geminiignore and .claudeignore) are identical and in sync
+GEMINI_IGNORE=".geminiignore"
+CLAUDE_IGNORE=".claudeignore"
+
+if [[ -f "$GEMINI_IGNORE" || -f "$CLAUDE_IGNORE" ]]; then
+  if [[ ! -f "$GEMINI_IGNORE" ]]; then
+    echo "Error: $CLAUDE_IGNORE exists but $GEMINI_IGNORE is missing." >&2
+    exit_code=1
+  elif [[ ! -f "$CLAUDE_IGNORE" ]]; then
+    echo "Error: $GEMINI_IGNORE exists but $CLAUDE_IGNORE is missing." >&2
+    exit_code=1
+  elif ! cmp -s "$GEMINI_IGNORE" "$CLAUDE_IGNORE"; then
+    echo "Error: $GEMINI_IGNORE and $CLAUDE_IGNORE are out of sync." >&2
+    echo "Please ensure both files contain the exact same ignore patterns." >&2
+    exit_code=1
+  fi
+fi
 
 if [[ $exit_code -eq 0 ]]; then
   echo "Success: All AI Agent Skills are correctly documented in $README_FILE."