83 lines
3.2 KiB
Markdown
83 lines
3.2 KiB
Markdown
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# Architecture: Why monkey-patch instead of patching files?
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The identity plugin uses **runtime monkey-patching** — no files in the
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Hermes repo are modified. This is the key design decision that eliminates
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the need for a fork.
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## The problem
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Kanban workers start with NO gateway user identity. The spawn function
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runs `hermes -p <profile> chat -q "work kanban task <id>"`. When Honcho
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initializes, `kwargs["user_id"]` is None, so it creates `user-default-*`
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peers.
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There is no Hermes plugin hook that fires at agent initialization before
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Honcho creates the session. The hooks available are:
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- `pre_gateway_dispatch` — only fires for gateway sessions (Discord, etc.)
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- `on_session_start` — fires AFTER Honcho has already initialized
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- `pre_tool_call` / `post_tool_call` — fire during tool execution, too late
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## The solution: runtime monkey-patch
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Python allows replacing any method on any class at runtime. The identity
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plugin does exactly this in its `register()` function:
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1. At plugin load time, it imports `HonchoMemoryProvider`
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2. Stores a reference to the original `_do_session_init` method
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3. Replaces it with a wrapper that checks the identity config first
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4. If the wrapper finds a peer name, it injects it via `kwargs["user_id"]`
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5. Otherwise, it calls the original method unchanged
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```python
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# In the plugin's register() function:
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provider_cls = plugins.memory.honcho.HonchoMemoryProvider
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_original_init = provider_cls._do_session_init
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@wraps(_original_init)
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def wrapper(self, cfg, session_id, **kwargs):
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if not kwargs.get("user_id"):
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resolved = get_peer_name() # reads config + env vars
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if resolved:
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kwargs["user_id"] = resolved
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return _original_init(self, cfg, session_id, **kwargs)
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provider_cls._do_session_init = wrapper
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```
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## Advantages over file patching
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| Aspect | File patching | Monkey-patching |
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|--------|--------------|-----------------|
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| Repo modifications | Yes (edits plugin file) | Zero |
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| Fork needed | Yes (git diff to maintain) | No |
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| Upgrades | Merge conflict on every pull | Unchanged |
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| Uninstall | Need to revert file changes | Plugin removed → clean |
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| Reliability | Works across restarts | Applied at every load |
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| Complexity | Simple file edit | Wrapping pattern |
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## When does the patch apply?
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- At plugin discovery time (Hermes startup)
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- Before any Honcho session is created
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- Before any agent is initialized
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- Before any kanban worker is spawned
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The Hermes plugin loader calls `register()` during gateway/agent startup,
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which means the patch is in place before any session can begin.
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## Safety guarantees
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1. **Non-destructive**: The original method is preserved via closure —
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removing the plugin restores original behavior with zero cleanup.
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2. **Idempotent**: `_apply_honcho_patch()` guards against double-patching
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via the `_original_init` sentinel.
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3. **Graceful degradation**: If the config file is missing, parsing fails,
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or the kanban DB is unavailable, the wrapper returns None → Honcho
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falls back to its default behavior (creating `user-default-*` peers).
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4. **No data loss**: The injected `kwargs["user_id"]` only affects what
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peer name Honcho assigns to the session's messages. It doesn't touch
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any existing data.
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