feat: add LlamaIndex integration

[DK09876]

Summary

• Add hindsight-llamaindex package: BaseToolSpec subclass + create_hindsight_tools() factory giving LlamaIndex agents persistent memory via retain/recall/reflect
• Full test suite (34 unit tests passing)
• Docs page at hindsight-docs/docs/sdks/integrations/llamaindex.md
• Blog post at hindsight-docs/blog/2026-03-23-llamaindex-memory.md
• Entry added to integrations.json

Test plan

• uv run pytest tests/ -v — 34 passed, 3 skipped (manual)
• uv run ruff check . && uv run ruff format --check . — clean
• E2E test with real Hindsight instance via test_manual.py
• Verify docs page renders correctly
• Verify blog post renders correctly

🤖 Generated with Claude Code

[nicoloboschi]

Review

Overall the PR is well-structured — clean separation of concerns (tools.py, config.py, _client.py, errors.py), comprehensive tests (34 unit tests), and good docs. A few things worth discussing:

Package structure doesn't follow LlamaIndex conventions

The PR uses hindsight_llamaindex/ as a standalone package. The standard LlamaIndex community integration uses namespace packages:

# PR has:
hindsight-integrations/llamaindex/hindsight_llamaindex/

# LlamaIndex convention:
llama-index-tools-hindsight/llama_index/tools/hindsight/base.py

With LlamaIndex, llama_index/ and llama_index/tools/ must NOT have __init__.py (PEP 420 implicit namespace packages). Main class goes in base.py, not tools.py.

If the package is ever submitted to LlamaHub or users expect from llama_index.tools.hindsight import HindsightToolSpec, it won't work. Fine as a standalone package but breaks the LlamaIndex ecosystem path.

Suggestion: Either restructure now, or document explicitly that this is standalone (not LlamaHub) and plan migration later.

Missing BaseMemory implementation

The PR only implements BaseToolSpec (agent-driven retain/recall/reflect). LlamaIndex also has BaseMemory which provides automatic memory — get() enriches prompts with recalled memories transparently, put() auto-retains messages.

The Mem0 integration (llama-index-memory-mem0) does both: BaseMemory for automatic recall/retain + tools for explicit agent control. This would align better with how Claude Code 0.3.x works — recall injected automatically into UserPromptSubmit hooks, retain on Stop events.

Consistency gaps with other Hindsight integrations

Feature	Claude Code 0.3.x	CrewAI	This PR
Auto-recall (inject into prompt)	✅ (hook)	✅ (Storage.search)	❌ (tool only)
Auto-retain (on conversation end)	✅ (hook)	✅ (Storage.save)	❌ (tool only)
Bank mission setup	✅	✅	❌
document_id generation	✅ (session+timestamp)	N/A	Static only
async: true retain	✅	✅	❌
context source label	✅ ("claude-code")	✅	❌
Error handling	Graceful (logs, continues)	Graceful	Raises HindsightError

Specific items:

• No document_id auto-generation — Claude Code generates {session_id}-{timestamp} for upsert/grouping. This only supports a static retain_document_id.
• No bank mission management — other integrations call set_bank_mission() on first use so the memory engine has context for fact extraction.
• No context param on retain — Claude Code passes "claude-code" as source label.
• Retain doesn't use async: true — other integrations use async retain for non-blocking storage. Valid for tool-based usage (agent expects confirmation) but worth noting.

Minor items

• config.py — default URL is production (https://api.hindsight.vectorize.io) while CrewAI defaults to http://localhost:8888. Should be consistent across integrations.
• _client.py — hardcoded timeout: 30.0. Claude Code uses different timeouts per operation (retain: 15s, recall: 10s, health: 5s).
• Blog post referenced in PR description but not in the diff.