channels/base.py: GatewayInvocation dataclass + Channel ABC (parse_invocation/render_result), mirroring Rein one layer up -- a channel turns an external invocation into what run_task_through_rein needs, and turns its result back into whatever the invocation medium expects. channels/cli_channel.py: CLIChannel, a pure refactor of what cli.py did inline -- argparse Namespace -> GatewayInvocation, result dict -> json.dumps(..., indent=2). cli.py's run handler is now a thin construct-parse-invoke-render wrapper. docs/channel-contract.md documents the pattern and sketches (without building) a second channel. Found and fixed a real bug while live-testing this refactor: ReinAharness's default cli_bin was still "agent-harness", stale from before HARNESS-WP-0002-T02's rename. 4 new tests (27/27 passing), plus a real live run through python3 -m glas_harness.cli against rein-aharness/real Claude Code confirming identical output shape and a real commit. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
76 lines
3.3 KiB
Markdown
76 lines
3.3 KiB
Markdown
# Channel contract
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How an external invocation reaches the gateway, per `GLAS-WP-0003`.
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Mirrors `docs/harness-contract.md`'s `Rein` at a different layer: `Rein`
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governs how a session runs once glas-harness has decided to run one; a
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`Channel` governs how an external caller (CLI today; a future Slack
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message, HTTP request, or scheduled trigger) gets translated into that
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decision in the first place, and how the result gets translated back.
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## Interface
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```python
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@dataclass
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class GatewayInvocation:
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"""Everything run_task_through_rein needs, channel-agnostic."""
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sandbox_profile: str
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repo: str
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title: str
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description: str
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actor: str = "agt"
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project: str = "glas-harness"
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report_to_hub: bool = True
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class Channel(ABC):
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"""Base class for concrete invocation channels (CLI, Slack, HTTP, ...)."""
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@abstractmethod
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def parse_invocation(self, raw: Any) -> GatewayInvocation:
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"""Turn a channel-specific invocation into a GatewayInvocation."""
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@abstractmethod
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def render_result(self, result: dict[str, Any]) -> Any:
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"""Turn a gateway result dict into whatever this channel returns."""
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```
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`src/glas_harness/channels/base.py`. A channel does not choose the rein
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or run the gateway itself — `cli.py`'s `main()` still does that, calling
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`parse_invocation`/`render_result` around the existing
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`run_task_through_rein` call. Keeping channel construction and gateway
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invocation separate (rather than folding gateway-calling into the
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`Channel` ABC itself) is what lets `CLIChannel` be a pure
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input/output mapper, easy to unit test without touching sand-boxer or a
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rein at all.
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## CLIChannel — the first, and so far only, implementation
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`src/glas_harness/channels/cli_channel.py`. Maps an argparse
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`Namespace` to `GatewayInvocation` (one field each, `--no-hub` inverts
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to `report_to_hub`) and renders a result dict as
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`json.dumps(result, indent=2)` — exactly what `cli.py` did inline before
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this existed. This was a refactor, not a behavior change: verified with
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a real live run through `python3 -m glas_harness.cli run ...` producing
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byte-identical output shape to the pre-refactor version, plus unit tests
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for the mapping in isolation (`tests/test_cli_channel.py`).
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## Adding a second channel (not done — pattern only)
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No second channel exists yet, and none should be built speculatively —
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same discipline as ADR-002/ADR-004 (generalize from a real second
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example, not in anticipation of one). If/when one is needed, e.g. a
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Slack channel:
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1. Implement `Channel` in `src/glas_harness/channels/slack_channel.py`:
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`parse_invocation` turns a Slack event payload into a
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`GatewayInvocation` (message text → `title`/`description`, a
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configured default `sandbox_profile`, the Slack user id as `actor`
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or `project`); `render_result` turns the result dict into a Slack
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message (success/failure, commit sha if present).
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2. Whatever process receives Slack events constructs the channel and
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calls `run_task_through_rein` the same way `cli.py` does — no change
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needed to `gateway.py`, `contract.py`, or any rein.
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3. If two real channels turn out to share invocation-parsing logic (e.g.
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both need the same `sandbox_profile` defaulting rule), factor that
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shared piece out then — not before, and not into the `Channel` ABC
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itself unless every channel needs it.
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