glas-harness/workplans/GLAS-WP-0003-first-channel-extension.md

id	title	status
GLAS-WP-0003	First channel extension: formalize the CLI channel contract	proposed

Scoped by GLAS-WP-0002-T04: of glas-harness's four charter pillars (unified API, profile catalog, extension platform, observability), "extension platform" is entirely unbuilt for channels — glas_harness.cli is a channel in substance (a way a caller invokes a harness session) but not in form (no Channel contract exists; it's just a CLI module).

This workplan does one thing: formalize the CLI as the first channel extension, so the contract exists before a second channel (Slack, HTTP, whatever) is attempted — not build a second channel now. Same discipline as ADR-002/ADR-004: generalize from a real second example, not in anticipation of one.

Task: Define the Channel contract

A Channel mirrors Rein's shape at a different layer: it turns an external invocation (CLI args, a Slack message, an HTTP request) into the sandbox_profile/repo/title/description/rein inputs run_task_through_rein needs, and turns its dict[str, Any] result back into whatever the invocation medium expects (stdout JSON for CLI, a Slack reply, an HTTP response body). Minimal ABC:

class Channel(ABC):
    @abstractmethod
    def parse_invocation(self, raw: Any) -> GatewayInvocation: ...

    @abstractmethod
    def render_result(self, result: dict[str, Any]) -> Any: ...

Document in docs/channel-contract.md, parallel to docs/harness-contract.md.

id: GLAS-WP-0003-T01
status: todo
priority: medium

Task: Refactor glas_harness.cli into a CLIChannel

src/glas_harness/channels/cli_channel.py: CLIChannel(Channel) implementing parse_invocation (argparse → GatewayInvocation) and render_result (→ json.dumps(..., indent=2), matching today's output exactly — this is a refactor, not a behavior change). cli.py becomes a thin main() that constructs a CLIChannel and calls it; existing CLI usage and output are unchanged.

id: GLAS-WP-0003-T02
status: todo
priority: medium

Task: Tests + verify no behavior change

Unit tests for CLIChannel.parse_invocation/render_result in isolation, plus re-running the existing live-proof commands (both reins) to confirm identical CLI output before/after the refactor.

id: GLAS-WP-0003-T03
status: todo
priority: medium

Task: Document the pattern for a second channel

A short section in docs/channel-contract.md sketching what a second channel (e.g. a Slack or HTTP channel) would need to implement, without building one — this workplan stops at "the contract exists and one real implementation proves it," matching the discipline applied throughout this session's other deferred-until-a-second-example decisions.

id: GLAS-WP-0003-T04
status: todo
priority: low