## Problem
`raptor.py` computes `n_neighbors = int((len(embeddings) - 1) ** 0.8)`
and
passes it to `umap.UMAP(...)`. In a dataset-scope RAPTOR build the first
layer's `embeddings` is the entire KB's chunk set, so this is
effectively
unbounded: ~93k chunks → n_neighbors ≈ 9,446.
UMAP's k-NN graph is `N × n_neighbors`; at these values the raw neighbor
arrays alone are ~14 GB (93k × 9446 × 16 B), and the symmetrized fuzzy
simplicial set + spectral init push peak well past 30 GB. The task
executor is OOM-killed inside `fit_transform` before any clustering runs
—
the log shows "Task has been received" with no "Cluster one layer" line
—
after which the unacked task re-queues and OOMs again in a loop.
The line above already flags this: `# Degrade too much ??`.
## Fix
Cap `n_neighbors` at 100. UMAP's neighborhood size has strongly
diminishing returns well below this (default 15; a few dozen already
captures global structure), so the ceiling preserves — likely improves —
cluster quality while bounding memory to O(N). Mirrors the existing
`n_components=min(12, len(embeddings) - 2)` clamp two lines down.
```diff
- n_neighbors = int((len(embeddings) - 1) ** 0.8)
+ n_neighbors = min(int((len(embeddings) - 1) ** 0.8), 100)
```
## Repro
Dataset-scope RAPTOR over a KB with ~90k+ chunks on a box with <~64 GB
available: executor OOM-killed in the first-layer UMAP `fit_transform`.
With the cap, first-layer UMAP peaks in low single-digit GB and the
build
proceeds to completion.
## Scope
Only affects large dataset-scope builds; file-scope RAPTOR already had
n_neighbors well under 100. No behavior change beyond the ceiling.
## Summary
- When KB retrieval fails (e.g. ES `AssertionError` on empty
`index_names`), `kbinfos` falls back to a dict without a `total` key
- `_async_update_chunk_info` then iterates over `chunk_info.keys()`
(which includes `total`) and tries `kbinfos['total']`, raising a
`KeyError`
- This error surfaces when using Tavily web retrieval in a chat with no
knowledge base attached
## Changes
- Add `'total': 0` to all default `kbinfos` dicts in
`_retrieve_information`
- Add `setdefault('total', 0)` guard after successful KB retrieval to
handle cases where the retrieval result omits the key
- Accumulate `total` correctly in the merge branch of
`_async_update_chunk_info`
## Test plan
- [ ] Start a chat with Tavily configured and no knowledge base
- [ ] Verify no `KeyError: 'total'` is raised
- [ ] Verify Tavily results are returned correctly
---------
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
### What problem does this PR solve?
Fixes#14051.
The chat UI already sends an `internet` flag with each request, but the
backend previously triggered Tavily web retrieval whenever
`prompt_config.tavily_api_key` was configured. As a result, web search
could still run even when the internet toggle was off.
This PR makes web search an explicit opt-in at request time:
- `tavily_api_key` only indicates that web search is available
- Tavily retrieval runs only when `internet` is explicitly enabled
- the same behavior now applies to both the normal retrieval path and
the deep-research / reasoning path
This also fixes the no-KB fallback case so chats without KBs fall back
to normal solo chat when `internet` is off.
### Type of change
- [x] Bug Fix (non-breaking change which fixes an issue)
