Document chunk plan caching and provenance

docs/integrations/json-output.md

@@ -91,6 +91,16 @@ The manifest fields are:
   identity;
 - `input_module`, `chunker`, `extractors`, `merger`, `normalizer`, and
   `output_encoder`: resolved module keys;
+- `chunk_plan`: payload-free provenance for the effective chunk plan. `mode`
+  is the effective cache mode; `action` is `reused`, `generated`,
+  `refreshed`, or `bypassed` when a plan was materialized. `requested_module`
+  is the current pipeline chunker, while `producer_input_module`,
+  `producer_module`, `producer_llm_profile`, `producer_references`,
+  `producer_metadata`, `source_digest`, `plan_digest`, `plan_schema_version`,
+  and `created_at` describe the stored or generated producer when available.
+  A cached plan can therefore identify a producer different from the requested
+  module. This object never embeds ranges, units, annotations, prompts,
+  responses, or reference content;
 - `module_metadata` and `artifact_lanes`: module and per-lane provenance,
   including prompt and response-schema provenance when provided;
 - `validator_chains`: resolved validation points and validators;
@@ -115,6 +125,10 @@ references.
 `validation_status` is `approved` when no outputs were rejected and `rejected`
 when one or more outputs were rejected.
 
+Producer warnings and the current run's chunk-validation warnings remain in
+`warnings.json`. The manifest records only provenance and decision summaries;
+empty producer-only values are omitted for compatibility with existing readers.
+
 `validator_chains` records the resolved validator chain for each validation
 point. Entries include stage, lane ID when applicable, module key, and validators
 with key and execution class. Empty chains are recorded with an empty