[JacobStephens2]

Summary

Claude and Codex each own their session protocol behind one Harness adapter. Sessions, Setup and User config use the registered adapters while preserving existing behavior.

src/harness/
├── adapter.rs          # shared interface, prompt delivery and optional hooks
├── claude.rs           # launch, Model check and Setup
├── claude/stream.rs
├── codex.rs            # launch, Model/Effort check and Setup
└── codex/              # catalog and stream

The adapter owns CLI/product names, new-session and Resume arguments, skill loading, skills location, instruction fallback, environment, stop signals, checks and stream parsing. Optional hooks cover instruction-file links and reading final text, usage and outcome after exit. Harness enumeration and choice messages come from adapter registrations.

Closes #434

Evidence

• Before: issue-432 passed all 55 existing Codex sessions, Harness choice, Setup, User config, progress lines and background work scenario tests.
  After: those same 55 tests pass unchanged through the adapters. Existing Harness, Session, progress, Setup and Codex parser test bodies are unchanged; ticket 1 adds no tests.
• cargo check --all-targets, cargo fmt --check and cargo clippy --all-targets -- -D warnings pass.
• UPDATE_PROMPTS=1 cargo test prompts_page: 8 tests pass; regeneration produces no diff in prompts/.
• cargo test: full suite passes (1086 passed, 0 failed, 0 ignored across 34 test binaries).
• thirdshift-code-review against issue-432 (d7e4a2c): Standards 0 findings; Spec 0 findings.

Test seams

• Existing scenario harness: real Runs against fake CLIs, observed through recorded calls, progress lines, logs and Run outcomes.
• Existing Setup outside-world fake: questions, Model/Effort checks and saved User config.
• Existing pure parser interfaces: session-stream condensation and Codex catalog parsing/settling.

Unaddressed findings

Standards

None: the review reported no findings.

Spec

None: the review reported no findings.

Merge Danger

Door: two-way

Can be reverted independently.

Blast Radius: Harnesses

Affects Harness selection, Setup and session execution across Runs and Resumes.

Built with codex · gpt-6.1-sol · xhigh