feat(openviking-plugin): native Session+Search integration with memory-first retrieval and observable fallback

[mczabca-boop]

Summary

This PR continues the OpenViking integration/pluginization line (TinyAGI#127 -> #1 -> #2) and adds the next stabilization layer focused on latency control, gate behavior, and runtime reliability.

In short: OpenViking remains fully pluginized, but prefetch is no longer “always-on”; it is now gated rule-first with optional LLM decisioning for ambiguous cases.

What This PR Adds

1) Rule-first prefetch gate inside openviking-context plugin

• Adds prefetch gate modes:
  • always
  • never
  • rule (default)
  • rule_then_llm
• Adds configurable gate controls:
  • prefetch_force_patterns
  • prefetch_skip_patterns
  • prefetch_rule_threshold
  • prefetch_llm_ambiguity_low
  • prefetch_llm_ambiguity_high
  • prefetch_llm_timeout_ms
• Force/skip/rule/llm decisions are all plugin-internal (no OpenViking-specific branching in core queue flow).

2) Expanded bilingual trigger vocabulary (CN/EN)

• Extended force/skip phrase coverage significantly in:
  • plugin rule evaluator
  • setup defaults
  • runtime defaults
• Improves practical recall/precision for real user phrasing in Chinese + English.

3) Optional LLM gate for ambiguous cases only

• In rule_then_llm, LLM is called only when rule verdict is ambiguous.
• LLM output is parsed as structured JSON (need_memory, reason).
• Timeout/error is fail-open to no-prefetch (llm_no) to avoid blocking the main response path.

4) Better hook-budget awareness in beforeModel

• Gate logs now include:
  • hook_budget_ms
  • hook_remaining_ms
  • prefetch_timeout_effective_ms
• If remaining hook budget is insufficient, plugin cleanly skips prefetch with explicit reason (instead of hidden timeout behavior).

5) Stability hardening around OpenViking runtime

• Adds vectordb dimension consistency guard in daemon startup:
  • compares expected dim (config) vs actual dim (runtime data metadata)
  • on mismatch, auto backup + rebuild runtime data dir
• Reduces recurring “expected X, got Y” instability loops.

6) Queue processor env loading fix

• queue-processor now loads .env (dotenv/config), ensuring plugin hook timeout/env knobs reliably take effect after normal restart.
• Fixes cases where .env had correct values but runtime still used defaults.

Observability Improvements

Per-turn logs now clearly expose gate behavior:

• prefetch_decision=force|rule_yes|rule_no|llm_yes|llm_no|disabled
• reason=...
• LLM gate timing + result (or timeout reason)
• Prefetch hit distribution remains visible (memory/resource/skill)

Key Files Touched

• src/plugins/openviking-context/index.ts
• src/plugins/openviking-context/prefetch-gate.ts
• src/queue-processor.ts
• lib/common.sh
• lib/setup-wizard.sh
• lib/daemon.sh
• README.md

Compatibility / Rollback

No change to core requirement:

• OpenViking remains optional and pluginized.
• Disabling OpenViking/plugin keeps TinyClaw normal behavior intact.

Feature flags remain compatible:

• TINYCLAW_OPENVIKING_CONTEXT_PLUGIN=0
• TINYCLAW_OPENVIKING_SESSION_NATIVE=1
• TINYCLAW_OPENVIKING_SEARCH_NATIVE=1
• TINYCLAW_OPENVIKING_PREFETCH=1
• TINYCLAW_OPENVIKING_AUTOSYNC=1

Gate defaults for new installs remain conservative:

• prefetch_gate_mode=rule (no LLM gate by default)

Validation Notes

Passed locally:

• npm run build:main
• npm run test:prefetch-parser
• npm run test:openviking-plugin

Manual runtime validation completed for:

• force path (prefetch_decision=force)
• rule-no path (prefetch_decision=rule_no)
• rule-then-llm path (prefetch_decision=llm_yes/llm_no)
• commit-required memory ingestion behavior (memory appears after successful session commit)

Risk / Follow-up

• LLM gate latency remains environment-dependent; timeout tuning still matters in production.
• If teams prefer lower latency by default, keep rule mode and enable rule_then_llm selectively.
• OpenViking upstream config behavior still requires explicit api_key in current version (pure env-substitution in ov.conf is not yet reliable).