CLI output-mode resolution sequences Effect.gen blocks and binds services mid-tree #373

Problem Statement

Deciding how the CLI renders (machine stream, colour support, output file) is one outside interaction — read flags and terminal, decide the mode, write through the opened stream — but its spine is scattered: six Effect.gen blocks in Output.ts and mid-tree service binding in StreamFile.ts and Cli.ts, next to a Cell that already exists but is run inline. The composition root belongs once at the process edge; today anyone changing output behavior edits procedures across three files, and nothing stops the next provideService from landing mid-tree again.

Goal

The output-mode interaction (probe → decide mode → open the stream) is exported as one typed pipe run once at the CLI's process edge, the services it needs are provided at src/main.ts rather than mid-tree, the gen-based functions it replaces are deleted, and pasting the old shape back fails pnpm --filter @systemfsoftware/stryker-js-cli typecheck because its home no longer exists.

Strangler slice: outside interaction = output-mode resolution and stream opening; intercept = packages/stryker-js/stryker-js-cli/src/main.ts (the process entry); forbidden shape = mid-tree provideService and multi-run gen sequencing on this path. No two-run lint exists in this repo and this slice creates none — the re-firing mechanism is the deleted surface (typecheck) plus the existing gold-path tests, per SJ-R4 in packages/stryker-js/AGENTS.md. Old paths for other interactions stay put; this slice moves only this one (SF5 coexistence).

Evidence: Current Behavior

packages/stryker-js/stryker-js-cli/src/StreamFile.ts:40-49 and the existing-but-inline Cell at packages/stryker-js/stryker-js-cli/src/Output.ts:396-480, at 7f11497e8b35da696e9f975df80f9714b91f79fa:

  return openClose.pipe(
    Effect.provideService(FileSystem.FileSystem, fs),
    Effect.provideService(Path.Path, path),
  )

export const outputModeProbeCell = Cell.layer({ ... })
// ...
Cell.run(outputModeProbeCell, flags).pipe(

Orientation

• The typed building blocks already exist in-repo: Workflow.make decisions (resolve-output-mode.workflow.ts) and Cell.layer/Cell.run (Output.ts). If the two-run shape later recurs as a defect, a rule earns admission then — named, dated defect plus a known-bad fixture, in its own change — not as part of this slice.
• src/main.ts is the package's process entry and already the place Logger.LogToStderr is bound (main.ts:58); it is the one legal binding site after the slice.
• Gold paths: the mode/colour assertions in tests/cli-contract.integration.test.ts (TERM/NO_COLOR matrix) and the package's unit tests under src/__tests__/.
• Other interactions in Cli.ts keep their current shape in this slice; migrating them is follow-on slices behind the same intercept.

Non-Counting Outcomes

• The pipe exists but the old gen-based functions remain exported and callable "just in case" — both paths live, the forbidden shape stays legal.
• A bespoke two-run or host-binding lint minted to prove this slice — no such defect has been dated in this repo, so the earn test fails (ENFORCEMENT.md gate economy).
• Services moved into a shared "context module" that is still imported mid-tree — the binding moved, the mid-tree import did not.
• Consumer-visible output (NDJSON stream shape, colour behavior, exit codes) changed as a side effect and tests were re-blessed to match.
• Success claimed because Output.ts now mentions Cell more, with no caller forced onto the new pipe.

Acceptance Criteria

• Critical: paste-back fails — with the old gen-based probe/open functions reintroduced beside the new pipe, pnpm --filter @systemfsoftware/stryker-js-cli typecheck exits non-zero or the duplicate shape is unreachable because its call sites are gone; the packet records the command, its non-zero exit, and the pasted snippet.
• At least one production caller drives the interaction through the new pipe (the CLI's run path uses it); grep shows the old gen-based equivalents deleted.
• pnpm --filter @systemfsoftware/stryker-js-cli test and test:contract exit 0 with the TERM/NO_COLOR stream-shape assertions unchanged.
• provide/run for this interaction appear once, in src/main.ts.