Implement Meeting Context V1 and extraction improvements

Introduce Meeting Context V1 with YAML schema, validation and template.
Support optional --meeting-context during chunk extraction.
Inject authoritative Meeting Context into extraction prompts.
Record Meeting Context provenance in extraction output.
Activate todos.md in shared prompt assembly.
Strengthen responsibility attribution and decision/todo boundaries.
Add focused Gold scenarios and validation tests.
Update architecture and pipeline documentation.

tests/test_extraction_protocol.py

@@ -5,12 +5,15 @@ from pathlib import Path
 
 from src.meeting_lab.extraction.extract_chunks import (
     EXTRACTION_CATEGORIES,
+    EXTRACTION_TASK_PROMPT_NAMES,
     build_prompt,
     extraction_path_for_chunk,
     normalize_current_schema,
     parse_json_response,
 )
+from src.meeting_lab.models.meeting_context import load_meeting_context
 from src.meeting_lab.protocol.build_protocol import build_protocol
+from scripts import run_gold_test
 
 
 class ExtractionProtocolTests(unittest.TestCase):
@@ -102,6 +105,41 @@ Final answer:
         self.assertIn("Extract each decision as one atomic commitment.", prompt)
         self.assertIn("Anna: Agreed.", prompt)
 
+    def test_build_prompt_includes_todo_prompt_file(self) -> None:
+        prompt = build_prompt("transcript.txt", "Nina: I will update it.")
+
+        self.assertEqual(EXTRACTION_TASK_PROMPT_NAMES, ("decisions.md", "todos.md"))
+        self.assertIn("Action-item responsibility rule:", prompt)
+        self.assertIn(
+            "A named responsible person may be extracted only when the transcript contains",
+            prompt,
+        )
+
+    def test_gold_runner_uses_shared_production_prompt_assembly(self) -> None:
+        self.assertIs(run_gold_test.build_prompt, build_prompt)
+
+    def test_no_context_and_meeting_context_prompts_use_same_task_prompt_set(self) -> None:
+        context = load_meeting_context(
+            Path("samples/real_live/project_process_meeting/meeting_context.yaml")
+        )
+
+        no_context_prompt = build_prompt("chunk_01_normalized.txt", "Anna: Agreed.")
+        context_prompt = build_prompt(
+            "chunk_01_normalized.txt",
+            "Anna: Agreed.",
+            meeting_context=context,
+        )
+
+        for prompt in (no_context_prompt, context_prompt):
+            self.assertIn("You extract decisions from meeting transcript text.", prompt)
+            self.assertIn("Action-item responsibility rule:", prompt)
+
+    def test_prompt_assembly_is_deterministic(self) -> None:
+        first = build_prompt("transcript.txt", "Nina: I will update it.")
+        second = build_prompt("transcript.txt", "Nina: I will update it.")
+
+        self.assertEqual(first, second)
+
     def test_build_protocol_groups_extraction_items(self) -> None:
         with tempfile.TemporaryDirectory() as directory:
             input_dir = Path(directory)