# Agent Guidelines for hermes-chatto-plugin

## This document stays contradiction-free

**AGENTS.md is a rulebook — every rule in it must be readable without having
to guess which one wins.**

If two passages turn out to conflict, or a rule admits two readings with
different outcomes, do not quietly choose one: point out the contradiction
where you hit it, name both passages, and resolve it here in the text so the
next reader cannot stumble into the same fork.

## What this plugin is

This plugin exists to connect a Hermes Agent to a Chatto server. All Chatto
API interaction goes through `chattolib` (vendored under `vendor/`) — never
hand-roll ConnectRPC/WebSocket calls the library already covers. When behaviour
is unclear on our side, the Chatto server source is the reference:

```bash
git clone https://github.com/chattocorp/chatto.git
```

The vendored copy corresponds to upstream `chattolib[realtime]`, the 0.4.x line
(realtime protocol v1) — Chatto servers older than v0.4.19 are not supported.
Respect that floor when refreshing `vendor/` via `vendor_chattolib.sh`
(see VENDORING.md).

## README.md is the human README

**Two audiences: AGENTS.md is read by agents with this source tree open;
README.md is read by humans who have not. That makes README.md the document
where ambiguity is not allowed.**

Everything a user meets first lives there — what the plugin is, how it
behaves, how to configure it. Unambiguous in practice means:

- **Say which Chatto you mean.** Server, chattolib and plugin all answer to
  "Chatto"; write the one you mean. (A capability-matrix column labelled just
  "Chatto" recently had to be asked whether it meant the plugin.)
- **One sentence, one reading.** If a claim can be parsed two ways, it is
  false in at least one of them — rewrite until only one parse remains.
- **No shorthand that needs the source.** Config keys, env vars and RPC names
  appear spelled out, never as "see adapter.py".
- **Keep versions current.** Compatibility claims must match reality — chattolib
  tracks Chatto upstream, so every `vendor/` refresh can move the supported
  server floor, and README.md has to move with it. ("Tested against Chatto
  v0.4.19" outlived its truth the moment the vendored copy became 0.4.20.)

## Behavioural contract

**These behaviours are promises to users, documented in README.md — adapter
changes must keep them, or consciously renegotiate the docs.**

- **Mention gating covers channels only.** With `require_mention` enabled,
  channel-kind rooms answer only messages @-mentioning the bot; group-kind
  rooms and DMs answer regardless. In channels with the gate off, a message
  aimed at someone else gets a 🫥 acknowledgement instead of an answer.
- **Threads stay threads.** An inbound thread reply keeps its thread context;
  a fresh room reply opens a thread under the incoming message unless
  `auto_thread` is disabled or the room is a DM.
- **Processing reactions.** 👀 while working, then ✅ or ❌ — driven by
  `on_processing_start`/`on_processing_complete` and the `reactions` setting,
  never applied to the bot's own events.
- **Length handling.** `send()` splits at 9900 chars against the 10000-char
  server limit; `edit_message()` refuses over-long content so callers fall
  back to `send()` rather than receiving silent truncation.

### Auth defaults to closed

Without `CHATTO_ALLOWED_USERS` and without `CHATTO_ALLOW_ALL_USERS=true`,
`_check_auth` denies everyone. Keep that fail-closed stance when touching the
auth path. `hermes_validate_config` rejects setting both options at once on
purpose, and `allow_all_users` hands every Chatto user full agent access
including tool use.

## Development

Work on this plugin happens against a real Hermes Agent checkout — set that up
first, everything else builds on it:

1. Fetch the Hermes Agent:

   ```bash
   git clone https://github.com/NousResearch/hermes-agent.git
   ```

2. Put this plugin at `hermes-agent/plugins/platforms/hermes-chatto-plugin`.
   Either clone this repo straight into that path, or link an existing checkout
   so you can keep working in your own copy:

   ```bash
   ln -s /path/to/hermes-chatto-plugin \
     hermes-agent/plugins/platforms/hermes-chatto-plugin
   ```

### Tests

`adapter.py` imports from `gateway.*`, which lives in the Hermes Agent rather
than this repo. Without its source on the `PYTHONPATH`, collection dies with
`ModuleNotFoundError: No module named 'gateway'` before a single test runs.
With the layout above:

```bash
PYTHONPATH=/path/to/hermes-agent uv run --with pyyaml pytest -q
```

`gateway.config` needs `pyyaml`, which is not among our dev dependencies.

### Readability

**Code is written for humans first and machines second — follow Clean Code
principles, with PEP 8 as the baseline.**

Everything in this repo gets read far more often than it gets written: by
maintainers revisiting it months later, and by agents working from these
guidelines. Optimising for that reader is not optional polish. Concretely:

- **PEP 8** for naming, layout and structure — Ruff enforces most of it
  mechanically, but the rules below are judgement calls no linter makes for you.
- **Small functions with one job.** If a function needs paragraphs of `#`
  commentary to explain its flow, split it until the code explains itself.
- **Names that say what they mean.** `_seed_room` beats `do_init`; a boolean
  reads as a question (`is_seen`, `retryable`). No single-letter names outside
  throwaway loop variables.
- **Comments explain why, not what.** The code already says what happens;
  the comment earns its line by recording intent, constraints, or the bug a
  guard exists to prevent (see `adapter.py` for the house style).
- **Explicit over clever.** Idiomatic Python beats micro-optimised trickery —
  comprehension over `map`/`filter` chains, dataclasses over dict-shaped blobs,
  early returns over nested conditionals.
- **Docstrings on every public method**, following PEP 257 — plus the override
  marker required by *Overriding* below.

### Linting & Type Checking

**Run Ruff on everything you touch, and leave no Pylance findings behind.**

Ruff is the linter and formatter for this repo:

```bash
ruff check .          # lint
ruff format .         # format
```

Fix what `ruff check` reports instead of adding `# noqa` — if a rule genuinely
does not fit here, that is a change to make deliberately, not inline.

Pylance (VS Code's Python language server) is the second gate. Its errors and
warnings are expected to be clean on files you edit; treat new squiggles as
unfinished work. Do not silence them with `cast(Any, ...)` or `# type: ignore` —
see *Typed access* below for why that trade hides real bugs.

## Configuration surface

**One field, three coordinated names — declared once on `ChattoConfiguration`.**

A config value lives as a `ConfigField` class attribute in `platform_config.py`.
From the attribute name it derives the `config.yaml` key under
`gateway.platforms.chatto.extra` (the *config_key*, overridable per field) and
the `CHATTO_*` environment variable (upper-cased config_key). Resolution order
per instance: env var → extra → default. Declaring a field is enough for the
adapter, the env-enablement seeding and the setup wizard to pick it up;
`plugin.yaml` additionally repeats the env names as wizard prompts, so keep
those entries in step.

When adding or renaming a field, also update the environment-variable table in
README.md — and document each option's default next to it, for env vars
(*Default* column) and `config.yaml` keys alike. A user reading only the
configuration docs must be able to predict what happens when they set nothing.
Secrets (`CHATTO_TOKEN`, `CHATTO_PASSWORD`) belong in `~/.hermes/.env`, never
in `config.yaml` — docs and setup wizard rely on that split.

## Typed access

**Work against the declared types. Do not reach for values dynamically when a
typed attribute exists.**

`chattolib` ships dataclasses with `py.typed` for everything it returns —
`Message`, `Asset`, `AssetUpload`, `Room`, `User`. Read their fields directly, so
a wrong name is a loud `AttributeError` at the first call and a type checker can
see it before that:

```python
upload_id = upload.upload_id            # yes
upload_id = str(getattr(cast(Any, upload), "id", ""))   # no
```

The second form cost us every single file upload. `AssetUpload` has no `id`
field — it is called `upload_id` — but `cast(Any, ...)` disables the check and
the `""` default turns the mismatch into an empty string. The result was an
error message blaming the server (`CreateUpload returned no upload ID`) for a
name we got wrong ourselves, and it survived in production because it never
raised.

So: no `cast(Any, ...)` on a value whose type is known, and no `getattr` with a
fallback default to paper over a field you are not sure about — look the field up
in `vendor/common/chattolib/types.py` instead. `getattr` is fine for genuinely
optional or duck-typed things (a handler that may not be set, a payload from an
untyped source), not for dodging a type.

Tests should exercise real library types too, not mocks shaped like them. The
upload bug was invisible because the tests replaced `_upload_asset` wholesale
with an `AsyncMock`, so no test ever touched a real `AssetUpload`.

## Overriding

**Every method that overrides a base-class method must say so in its
docstring, closing with the marker line `BasePlatformAdapter override` — the
pattern already used throughout `adapter.py`.**

This plugin lives by subclassing (`ChattoAdapter` overrides `BasePlatformAdapter`
methods throughout), so an override is not an implementation detail — it is the
contract between plugin and platform. Follow the existing form: first line says
what the method does, the body spells out what changes about the inherited
behaviour, and the last line names the parent class:

```python
async def edit_message(self, chat_id, message_id, content, *, finalize=False):
    """Edit a message we previously sent, via MessageService/UpdateMessage.

    Without this override the base class reports "Not supported" and every
    incremental streaming update arrives as a *new* message. Content beyond
    the per-message limit is refused so callers fall back to ``send()``.

    BasePlatformAdapter override
    """
```

## Capabilities

**When you extend what the adapter can do, keep the startup banner current.**

`_capabilities()` in `adapter.py` logs what the plugin supports at registration,
so starting it up tells you what is available instead of making you read the
source. Whether a capability counts is derived from real overrides: it only
counts when `ChattoAdapter` replaces the `BasePlatformAdapter` method. The label
for it, however, lives in `_CAPABILITY_LABELS` and is *not* discovered
automatically.

So when you add an overridden `BasePlatformAdapter` method:

1. Add an entry to `_CAPABILITY_LABELS` (method name → wording that means
   something to someone who has not read the code). Skip this and the plugin can
   do the thing but says so nowhere.
2. Check whether the `platform_hint` in `register()` needs to mention it. That
   hint goes into the system prompt and is the only way the model learns what the
   channel can do — without it the agent falls back to shelling out.
3. Add a test in `TestRegistration` if the capability is user-visible.
4. Update the capability matrix and feature notes in README.md — that is the
   public version of the same list.

The reverse holds too: drop a method and its line disappears from the log on its
own, but its `_CAPABILITY_LABELS` entry should go with it, along with its row in
the user docs.

## Shell Scripts

**Always run `shellcheck` after editing any shell scripts.**

```bash
shellcheck path/to/script.sh
```

Or validate all shell scripts in the project:

```bash
find . -name "*.sh" -exec shellcheck {} \;
```

### Configuration

Project-specific shellcheck rules are defined in `.shellcheckrc`. Default severity is `error` to catch all issues.

### Why

- Prevents syntax errors and common pitfalls (e.g., missing quotes, unsafe variable expansions)
- Ensures portability across different shell environments
- Maintains code quality and security standards

### Integration

Consider adding a pre-commit hook for automatic validation:

```yaml
# .pre-commit-config.yaml
repos:
  - repo: https://github.com/koalaman/shellcheck-precommit
    rev: v0.9.0
    hooks:
      - id: shellcheck
        args: [--severity=error]
```
