The context/output/scaffold extraction left src/cli/main.js with dead local helper slabs and one missing VS Code settings constant set. This commit removes the unreachable local copies, routes setup auto-finish reporting through the shared formatter, restores the missing context exports, and updates seam tests to track the new ownership boundaries.

Constraint: This follow-up had to resume in the existing agent worktree after the prior write-review limit interrupted verification
Rejected: Leave the dead install/setup/doctor helper slabs in src/cli/main.js | keeps stale ownership and hides missing-export regressions
Confidence: high
Scope-risk: moderate
Reversibility: clean
Directive: Keep extracted CLI seams owned by src/context.js, src/output/index.js, and src/scaffold/index.js; do not reintroduce local helper copies in src/cli/main.js
Tested: node --check src/cli/main.js; node --check src/context.js; node --check src/output/index.js; node --check src/scaffold/index.js; node --test test/cli-args-dispatch.test.js; node --test test/metadata.test.js test/setup.test.js test/doctor.test.js; openspec validate agent-codex-split-cli-main-args-dispatch-2026-04-22-13-48 --type change --strict; openspec validate --specs
Not-tested: gx branch finish / PR merge / cleanup after this follow-up commit