chore(agents): add session log

Author: sanjayankur31

.agents/2026-08-03.md

@@ -43,3 +43,44 @@ Character-count logging for LLM invocations, per-vector-store retrieval settings
 
 - Commits today: `615c684` chars logging, `1d76058`/`56ef54a`/`1bfc9fb` per-store k + tests, `9a8d56a`/`f31dcea` docs + config updates, `f590af5` logging standardization.
 - `utils_pkg/AGENTS.md` example updated from `setup_logging` -> `setup_root_logger` (uncommitted).
+
+---
+
+## Session 2: HuggingFace token-window / max-token handling, invocation error handling, and frontend error display
+
+**Authoring agent:** opencode
+
+## Objective
+
+Fix HuggingFace providers reserving the entire context window as output when `max_tokens` is unset (causing spurious ~1M output-window reports and rate limiting), handle invocation errors adaptively, and stop rendering backend errors as chat bubbles in the frontend. Steps 1-4 done; Step 5 (frontend) pending.
+
+## Completed
+
+1. **models.dev catalog client** (`models_catalog.py`): lazy fetch of the models.dev api.json with in-memory + 1-day on-disk cache, offline fallback, graceful `None` for providers/models missing from the catalog.
+2. **Invocation error classification**: `LLMInvocationErrorCategory` enum (errors.py) + `classify_llm_invocation_error()` (llm.py) -- tolerant regex classifiers with cause-chain unwrapping. `looks_like_structured_output_error` folded into the `STRUCTURED_OUTPUT_REJECTED` category.
+3. **Always-bounded max output tokens**: every invoke now gets a finite, clamped max-output param. `resolve_output_token_limit()` resolves explicit param -> generic `max_output_tokens` -> per-role fallback, then clamps to catalog `limit.output` and to `context - estimated input` (chars//4), since HF applies a **total budget** (input + output <= context). `LLMModel.provider_defaults` (Layer 4) + optional `providers` config section; `_provider_defaults_for_role` shared on `BaseLangGraph`. Per-node `max_output_tokens` added to RAG/shared node `model_defaults`; code-pkg deferred to the `plan` role default.
+4. **Adaptive retry** in `BaseLLMNode`: `CONTEXT_OVERFLOW` shrinks the output window and retries (<=3x); `finish_reason="length"` grows it and retries (<=2x); rate-limit and other errors re-raise immediately. Bails when the window cannot move.
+
+## Errors and Lessons
+
+- **Do not reuse tenacity for this retry.** Tenacity (api, mcp tools) retries the *identical* call with backoff; our retry must change parameters between attempts, which tenacity's decorator cannot do cleanly. Backoff is also most useful for rate-limit retries, which we deliberately surface.
+- **`ChatHuggingFace` uses `max_tokens`** (mapped internally to `max_new_tokens`), not `max_new_tokens` -- only ollama is `num_predict`. Using `max_new_tokens` gets stripped by provider field filtering. Verify against the installed provider class.
+- **Resolver "explicit wins" precedence bit the retry**: setting the generic `max_output_tokens` key while a stale explicit `max_tokens` was present meant the window never changed; fix is to set the provider token param directly, then re-clamp.
+- Async tests must NOT inherit `unittest.TestCase` (pytest-asyncio auto mode silently skips those coroutines).
+- Pre-existing unrelated failures unchanged: utils_pkg 6 (api-router 422s, stores-retrieval env var), rag_pkg 2 (tools_picker display).
+- `ty` diagnostics went 50 -> 46 (added missing type annotations to `klea_code.py`).
+
+## Notes
+
+- HF's total-budget behavior is why output must always be bounded and clamped against `context - input`.
+- `deployments/huggingface` submodule dirt and `VECTOR_STORES_IGNORED` remain the user's local disposition.
+
+## Next session
+
+1. **Step 5: errors out of the chat pane**
+   - `api/chat.py`: `/query/stream` emits a structured `error` event (`message`, `error_type`, `node`) and stops storing errors as assistant messages; `/query` drops the error `store.add_message` too.
+   - `ui/web/nicegui/runner.py` `_do_stream`: `error` events + `httpx.RequestError` -> `ui.notification` toasts, never chat bubbles.
+   - `ui/tui/repl.py`: errors to stderr, not the AI response.
+   - Tests: extend `test_api_routers.py` for the error event shape + nothing persisted.
+2. **Step 6: docs/config + verification** -- example configs demonstrating the `providers` section, tutorial docs, full verification.
+3. Optional follow-ups (out of scope): history-size-based memory summarisation on context overflow, code-pkg per-node `max_output_tokens` tuning.