docs(hindsight): document recall_types workaround

[yu-xin-c]

Summary

• document the Hindsight recall_types config knob in the plugin README
• add a repeated recall / memory bloat note with the "recall_types": ["observation"] mitigation
• surface the same trade-off from the Memory Providers docs page

Fixes #21698

Testing

• Not run; docs-only change.

[bionicbutterfly13]

Thanks for documenting the recall_types trade-off — useful addition. One complementary note you might fold in: the observation-only default also has a freshness cost that isn't captured here yet.

Freshness trade-off. Restricting recall to observation (the default since #34079) also narrows which recently retained facts recall can surface. Observations are Hindsight's consolidated layer, built from raw world/experience facts by a consolidation process whose timing isn't visible from the plugin. In a single local-daemon probe (n=1 — not a general Hindsight guarantee), a just-retained fact was not returned by observation-only recall right after retain; raw-type recall returned it immediately, and observation-only recall returned it ~45s later once an observation had consolidated. This applies to both auto-recall and the hindsight_recall tool; the reflect path is unaffected (it doesn't pass fact_types). For agents that retain and recall within the same session, adding experience (e.g. "recall_types": "observation,experience") surfaces fresh facts, at the cost of some of the duplication observation-only avoids.

Happy to open a small follow-up PR with this after yours merges if that's easier than editing here.

[yu-xin-c]

Folded this in with fec899e4e.

I kept it as a trade-off note rather than a fixed timing claim: observation-only recall avoids duplicated raw facts, but can lag freshly retained world / experience facts until they consolidate. The docs now call out observation,experience for same-session freshness and observation,world,experience for broadest recall, and note that hindsight_reflect is unaffected.

[yu-xin-c]

Closing because the linked issue #21698 was closed by maintainers as not planned. The documentation work remains available in the branch if the direction is revisited.