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Quanzheng Long
9100f2c682
Add a standalone recovery tool at `examples/delta-channel-dump/` for operators rolling back from langgraph >= 1.2 / deepagents 0.6.x to an older runtime that does not understand `EXT_DELTA_SNAPSHOT` msgpack blobs. Without this, channels like `messages` can appear empty after rollback because the old reducer does not decode delta snapshots. `dump.py` connects directly to Postgres, walks the checkpoint parent chain (mirroring `aget_delta_channel_history`), decodes msgpack blobs via `ormsgpack` with a hand-rolled EXT 0–7 hook (no langgraph imports), and emits JSON with per-channel `seed` + oldest-to-newest `writes`. The operator reduces and re-applies via `update_state` manually. ## Scope - Postgres checkpointer only - Deps: `psycopg[binary]`, `ormsgpack` (not added to repo `pyproject.toml` — operator installs at runtime) - No reducer application, no DB writes, no AES/custom encryption support (fails loudly on encrypted blob types) ## How verified - E2E against local Postgres: 15 runs of `delta_channel_messages_freq` (`snapshot_frequency=10`) - Asserted `delta_kind == "snapshot"`, `len(seed) == 10`, `len(writes) == 5`, message ids `ai-0`..`ai-14` - Confirmed portability: fresh venv with only `pip install "psycopg[binary]" ormsgpack` produced identical output
LangGraph examples
This directory is retained purely for archival purposes and is no longer updated.
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The examples previously found here have been moved to the consolidated LangChain documentation. This directory remains available for historical reference, but new examples and usage guidance are published in the docs.
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