Bound persisted status diagnostics (#5174)

* Bound persisted status metadata (#5161)

* Fix Windows status output assertion (#5161)

* Address adversarial review findings (#5161)

Author: Widthdom

AGENT_GUIDE.md

@@ -143,7 +143,8 @@ CI watching must be bounded. Do not loop indefinitely.
 
 ## Status Contract
 
-- `status --json` and related JSON/MCP payloads currently expose the trust fields documented in `README.md` and `DEVELOPER_GUIDE.md`, including `fold_ready`, `fold_ready_reason`, `graph_table_available`, `graph_data_current`, `index_complete`, `index_incomplete_reasons`, `issues_table_available`, `file_issues_data_current`, `migration_in_progress`, `sql_graph_contract_ready`, `sql_graph_contract_degraded_reason`, `hotspot_family_ready`, `hotspot_family_degraded_reason`, `language_readiness`, `csharp_symbol_name_ready`, `csharp_metadata_target_ready`, `csharp_metadata_target_degraded_reason`, `indexed_head_commit`, `workspace_verified_head_sha`, `worktree_head_changed`, `indexed_head_sha`, `indexed_head_branch`, `indexed_head_timestamp`, `commits_ahead_of_indexed_head`, `head_freshness`, `index_writer_version`, `index_newer_than_reader`, `index_newer_than_reader_reason`, `unknown_extension_file_count`, `unknown_extension_files`, `unknown_extension_files_truncated`, `unknown_extension_file_path_limit`, `unknown_extension_extension_counts`, `unknown_extension_category_counts`, `unknown_extension_groups`, `unknown_extension_group_count`, `unknown_extension_groups_truncated`, `unknown_extension_group_limit`, `unknown_extension_group_omitted_count`, `unknown_extension_guidance`, `extractors`, `git_executable`, `path_case_sensitive`, `data_dir`, `data_dir_source`, `data_dir_mode`, `db_file_mode`, `database_permission_policy`, `database_permission_diagnostics`, `mac_profile`, `mac_profile_diagnostics`, `db_size_bytes`, `wal_size_bytes`, `db_pragma_settings` (`journal_mode`, `synchronous`, `wal_autocheckpoint`, `busy_timeout_ms`, `page_count`, `freelist_count`, `page_size`, `auto_vacuum`), `prepared_command_cache` (`count`, `capacity`, `hit_count`, `miss_count`, `eviction_count`), `maintenance_guidance`, WAL checkpoint diagnostics (`read_only_fallback`, `wal_checkpoint_attempted`, `wal_checkpoint_succeeded`, `wal_checkpoint_skipped_reason`, `wal_checkpoint_failure_reason`, `wal_checkpoint_busy`, `wal_checkpoint_log_page_count`, `wal_checkpoint_checkpointed_page_count`, `wal_checkpoint_remaining_page_count`, `read_only_immutable_fallback`, `wal_stale_snapshot_risk`, `wal_stale_snapshot_reason`), `symbol_kinds`, `symbols_by_language`, status kind cap metadata (`symbol_kind_limit`, `symbol_kind_name_limit`, `symbol_kind_total_count`, `symbol_kind_omitted_count`, `symbol_kind_names_truncated`, `symbols_by_language_kind_total_counts`, `symbols_by_language_kind_omitted_counts`, `symbols_by_language_kind_names_truncated`), `process`, `last_index_run`, `last_failed_or_partial_index_run`, `last_failed_or_partial_index_run.progress_persisted`, `last_failed_or_partial_index_run.recovery_hint`, `last_failed_or_partial_index_run.file_errors`, `last_workspace_freshened_at`, `hooks`, `hook_diagnostics`, `trust_overrides`, MCP-only `mcp_session`, `mcp.rate_limit.bucket_limit`, `mcp.rate_limit.bucket_limit_rejection_count`, and the `status --check`-only `stale_after_seconds` / `index_age_seconds` threshold audit fields and `repair_commands`.
+- `status --json` and related JSON/MCP payloads currently expose the trust fields documented in `README.md` and `DEVELOPER_GUIDE.md`, including `fold_ready`, `fold_ready_reason`, `graph_table_available`, `graph_data_current`, `index_complete`, `index_incomplete_reasons`, `issues_table_available`, `file_issues_data_current`, `migration_in_progress`, `sql_graph_contract_ready`, `sql_graph_contract_degraded_reason`, `hotspot_family_ready`, `hotspot_family_degraded_reason`, `language_readiness`, `csharp_symbol_name_ready`, `csharp_metadata_target_ready`, `csharp_metadata_target_degraded_reason`, `indexed_head_commit`, `workspace_verified_head_sha`, `worktree_head_changed`, `indexed_head_sha`, `indexed_head_branch`, `indexed_head_timestamp`, `commits_ahead_of_indexed_head`, `head_freshness`, `index_writer_version`, `index_newer_than_reader`, `index_newer_than_reader_reason`, `unknown_extension_file_count`, `unknown_extension_files`, `unknown_extension_files_truncated`, `unknown_extension_file_path_limit`, `unknown_extension_extension_counts`, `unknown_extension_category_counts`, `unknown_extension_groups`, `unknown_extension_group_count`, `unknown_extension_groups_truncated`, `unknown_extension_group_limit`, `unknown_extension_group_omitted_count`, `unknown_extension_guidance`, `extractors`, `git_executable`, `path_case_sensitive`, `data_dir`, `data_dir_source`, `data_dir_mode`, `db_file_mode`, `database_permission_policy`, `database_permission_diagnostics`, `mac_profile`, `mac_profile_diagnostics`, `db_size_bytes`, `wal_size_bytes`, `db_pragma_settings` (`journal_mode`, `synchronous`, `wal_autocheckpoint`, `busy_timeout_ms`, `page_count`, `freelist_count`, `page_size`, `auto_vacuum`), `prepared_command_cache` (`count`, `capacity`, `hit_count`, `miss_count`, `eviction_count`), `maintenance_guidance`, WAL checkpoint diagnostics (`read_only_fallback`, `wal_checkpoint_attempted`, `wal_checkpoint_succeeded`, `wal_checkpoint_skipped_reason`, `wal_checkpoint_failure_reason`, `wal_checkpoint_busy`, `wal_checkpoint_log_page_count`, `wal_checkpoint_checkpointed_page_count`, `wal_checkpoint_remaining_page_count`, `read_only_immutable_fallback`, `wal_stale_snapshot_risk`, `wal_stale_snapshot_reason`), `symbol_kinds`, `symbols_by_language`, status kind cap metadata (`symbol_kind_limit`, `symbol_kind_name_limit`, `symbol_kind_total_count`, `symbol_kind_omitted_count`, `symbol_kind_names_truncated`, `symbols_by_language_kind_total_counts`, `symbols_by_language_kind_omitted_counts`, `symbols_by_language_kind_names_truncated`), `process`, `last_index_run`, `last_failed_or_partial_index_run`, `last_failed_or_partial_index_run.progress_persisted`, `last_failed_or_partial_index_run.recovery_hint`, `last_failed_or_partial_index_run.file_errors`, `status_metadata_diagnostics`, `last_workspace_freshened_at`, `hooks`, `hook_diagnostics`, `trust_overrides`, MCP-only `mcp_session`, `mcp.rate_limit.bucket_limit`, `mcp.rate_limit.bucket_limit_rejection_count`, and the `status --check`-only `stale_after_seconds` / `index_age_seconds` threshold audit fields and `repair_commands`.
+- Persisted status subdocuments for reference-extraction cap hits, rebuild reclaim, and failed-file diagnostics use a 512 KiB UTF-8 input limit and maximum JSON depth 16 before semantic validation. Preserve the shared 50-item writer/reader limits, nested reason and string budgets documented in `README.md` and `DEVELOPER_GUIDE.md`, omission of only the rejected subdocument, and `status_metadata_diagnostics` reasons `raw_size_exceeded`, `invalid_json`, and `semantic_validation_failed`. Human first-failure and recovery-hint fields must pass through the bounded control-flattening formatter while accepted structured JSON remains unchanged.
 - `status --check` repair actions are structured by `name`, `action`, `args`, `mutation_class`, `safety_class`, and `safety_notes`. Preserve compatibility `reason` as the first trigger and ordered `reasons` as the complete trigger set. Deduplicate only exact structured identities; different targets, options, actions, mutation classes, or safety semantics must remain distinct. JSON and human output must use the same deduplicated order. Human output must preserve platform-aware shell quoting, visibly escape control characters to keep each repair action on one diagnostic line, and leave structured JSON `args` unchanged.
 - `maintenance_guidance.fts_optimization` is the shared, read-only recommendation contract for status, explain, optimize preview, and optimize execution. Keep `recommended`, `action`, `reason`, `threshold_writes`, `observed_writes`, and `state` synchronized; stale or unavailable snapshots must not recommend mutation.
 - A successful CLI or MCP `index --rebuild` evaluates the shared freelist warning threshold after the index transaction commits. Incremental-auto-vacuum databases may run bounded `PRAGMA incremental_vacuum`; legacy databases must skip automatic reclaim instead of running a full `VACUUM`. Preserve the immediate index-result and persisted `last_index_run.rebuild_reclaim` telemetry, stable states/reasons, before/after ratios and byte/page counts, and the rule that reclaim failure never reclassifies an already committed index run as failed.