Implement Semantic Consolidator V0

- add deterministic canonicalization support for extraction items
- add facts-only semantic consolidation using local Ollama
- preserve source evidence and validate complete fact coverage
- add conservative merge rules and non-LLM tests
- record the first validated real-life consolidation benchmark
- document current scope, limitations and next evaluation step

docs/experiments.md

@@ -954,9 +954,10 @@ marks contradictions or uncertainty.
 
 Decision:
 
-Deterministic canonicalization is the next implementation step after stable
-local extraction, followed by semantic consolidation. Canonical Meeting
-Knowledge and final output views are planned, not implemented.
+Deterministic canonicalization is implemented as Canonicalizer V1. The first
+semantic consolidation milestone is implemented as Semantic Consolidator V0 for
+facts-only duplicate detection. Broader semantic consolidation, Canonical
+Meeting Knowledge and final output views remain planned.
 
 Lessons learned:
 
@@ -1037,3 +1038,134 @@ Evidence:
 - `PROJECT_KNOWLEDGE.md`
 - `docs/output-views.md`
 - See EXP-0017 and EXP-0019.
+
+## EXP-0021 - Canonicalizer V1
+
+Status: Accepted
+
+Date or period: 2026-07-31
+
+Hypothesis:
+
+Independent chunk extraction JSON can be converted into a stable deterministic
+intermediate format before any semantic LLM consolidation is attempted.
+
+Setup:
+
+Canonicalizer V1 discovers `chunk_*_extraction.json` files in stable chunk
+order, validates required categories, normalizes category names and basic field
+structure, parses existing legacy string formats where safe, trims redundant
+whitespace, assigns deterministic IDs, preserves original values and source
+references, and merges only exact duplicates when all semantic fields are
+identical.
+
+Inputs:
+
+- Synthetic unit-test fixtures.
+- Existing nine extraction JSON files under
+  `samples/whisper/meeting_speech_cleaned_chunks/`.
+
+Model / configuration:
+
+- No LLM.
+- CLI module: `meeting_lab.consolidation.canonicalize`.
+
+Result:
+
+Canonicalizer V1 produces `schema_version`, `source_files`, `stats` and
+`items`. It is deterministic preparation for the future Semantic Consolidator
+and is not Canonical Meeting Knowledge.
+
+Decision:
+
+Canonicalizer V1 is the current implemented deterministic canonicalization
+stage. Semantic Consolidator V0 now uses this representation for facts-only
+semantic duplicate detection; broader semantic consolidation and Canonical
+Meeting Knowledge remain planned.
+
+Lessons learned:
+
+Exact duplicate handling, source-reference preservation and legacy string
+parsing can be tested without model calls. Any uncertain semantic merge remains
+out of scope for this stage.
+
+Evidence:
+
+- `src/meeting_lab/consolidation/canonicalize.py`
+- `tests/test_canonicalize.py`
+- `docs/data-models.md`
+- `docs/pipeline.md`
+
+## EXP-0022 - Semantic Consolidator V0 facts-only merge
+
+Status: Accepted
+
+Date or period: 2026-07-31
+
+Hypothesis:
+
+The Canonicalizer V1 output contains enough stable structure for a local LLM to
+identify semantically equivalent fact items without losing source coverage or
+changing non-fact categories.
+
+Setup:
+
+Semantic Consolidator V0 consumed the existing Canonicalizer V1 benchmark JSON,
+selected only items with `category: "fact"`, and sent one bounded consolidation
+request to local Ollama. The merge rules required semantic equivalence, not
+topic similarity, and validation required every source fact ID to appear
+exactly once.
+
+Inputs:
+
+- `samples/benchmarks/canonicalizer_v1/canonicalized_extractions.json`
+- 33 fact items.
+
+Model / configuration:
+
+- `qwen3.5:9B`
+- Ollama endpoint: `http://127.0.0.1:11434/api/generate`
+- Thinking disabled.
+- One LLM call.
+- `num_ctx=32768`
+- `num_predict=4096`
+
+Result:
+
+- Runtime: 390.119 seconds on the current machine.
+- Merged fact groups: 1.
+- Source facts involved in merges: 2.
+- Singleton fact groups: 31.
+- Validation: passed.
+- No source fact was lost or duplicated.
+- Non-fact categories remained unchanged.
+
+Accepted merge:
+
+- `fact_0025` + `fact_0031`
+- Canonical statement: "Der Leiter F&E führt die Projektliste auf dem
+  zweiwöchentlichen Schnittstellen-Stand-Up."
+
+Decision:
+
+Semantic Consolidator V0 is complete for its current narrow scope:
+conservative facts-only semantic duplicate detection with source evidence
+preserved. The selected `report.md` and `consolidated_extractions.json`
+benchmark artifacts should be versioned for later comparison. The raw model
+response remains a local diagnostic artifact and is not versioned.
+
+Lessons learned:
+
+Semantic duplicate consolidation is technically viable and conservative enough
+for continued evaluation, but broader semantic synthesis remains a separate
+future stage. The measured runtime is useful for this machine and run, but
+should not be generalized into a universal benchmark.
+
+Evidence:
+
+- `src/meeting_lab/consolidation/consolidate_facts.py`
+- `prompts/consolidate_facts.md`
+- `tests/test_consolidate_facts.py`
+- `samples/benchmarks/semantic_consolidator_v0/report.md`
+- `samples/benchmarks/semantic_consolidator_v0/consolidated_extractions.json`
+- Local diagnostic only: `samples/benchmarks/semantic_consolidator_v0/raw_model_response.txt`