Repo Delegate

Repo delegate

Hand a well-scoped implementation task to another harness and get a report back. Same structure as repo-review: one prompt template (PROMPT.md), one runner script per harness, a template for adding more. The delegate edits files and runs checks; the caller reviews the diff and commits — delegates never touch git state.

When

• A fix round produced precise per-finding prescriptions (repo-review loop).
• Bulk implementation against a written contract (repo-build-pr delegation).
• A second, independent implementation attempt from a different model family.

Not for: architecture, contracts, go/no-go calls — those stay with the orchestrating model (see repo-build-pr's model orchestration rules).

How

1. Write the task brief to a file. Like a contract: exact scope and file ownership, the interface to build against, repo conventions to follow, and an instruction to report deviations instead of improvising. If the brief would be longer than the diff, don't delegate. For a defect fix, make the gate fail first: encode the bug as a failing regression check (test or fixture assertion) before dispatch and say so in the brief — the delegate's "gate passed" is then proof the defect died, not a claim.

   State invariants, not failure-path branches. A brief that dictates what to do when something goes wrong ships the orchestrator's unexamined premise straight into the code, and the delegate will implement it faithfully. Say "never type into an unintended app"; do not say "on timeout post the keystroke anyway so text is not lost". Before writing any "or else X is lost" rationale, verify X can actually be lost. In PR #676 it could not — the transcript was already on the clipboard and in history — so the brief's own safety clause recreated the exact bug the PR existed to fix, and only a cross-harness adversarial run caught it.

   Mutation-check any fixture the delegate authored. A test written by the same agent that wrote the fix can pass for reasons unrelated to the fix. Revert the fix, confirm the test goes red, restore. PR #676: a delegate's "notice does not fire" test asserted the absence of a label in a state where an unrelated guard already prevented it — green with the fix removed. PR #677 is the harder version: a delegate rewrote an existing test so its own regression would pass.

2. Fill and dispatch (-t is the brief file; gate defaults to pnpm check && pnpm typecheck && pnpm test):

   scripts/run-codex.sh  -t <brief.md> [-C <worktree>] [-g "<gate>"] [-c "<extra constraints>"] [-o <out>] \
                         [-m <model>] [-e <effort>] [-S <tier>]
   scripts/run-claude.sh -t <brief.md> [same flags, minus -S; -m takes
                         sonnet|opus|haiku (default opus), -e takes
                         low|medium|high|xhigh|max (default medium — the
                         brief carries the hard thinking; bump for subtle
                         defect fixes)]
   

   Codex model/effort/speed (defaults come from ~/.codex/config.toml; only pass a flag when the user asked for something specific):

   Allowed models (for now): gpt-5.6-sol (config default; main work), gpt-5.6-terra (quick review/feedback passes), gpt-5.6-luna (cheap fast bulk; not a primary pick) — the script rejects anything else.

   User says	Flag
   "sol" / "terra" / "luna"	-m gpt-5.6-sol / -m gpt-5.6-terra / -m gpt-5.6-luna
   "think hard"	-e high
   "max effort"	-e xhigh (rarely needed — high covers almost everything)
   "quick pass" / "low effort"	-e low (or minimal/none)
   "fast"	-S fast (bills ~2.5x credits — see below)
   "standard speed"	-S standard (the script's default)

   Effort is none|minimal|low|medium|high|xhigh (validated client-side; the API only rejects a bad value after the session has started). Calibration: medium is the workhorse, high for genuinely hard briefs, xhigh almost never — 5.6 at medium/high already runs long and completes tasks end-to-end.

   Speed maps to Codex's service_tier config: fast = priority, standard = default — the only two tiers the gpt-5.6 models advertise; anything else is silently dropped by Codex, so the script fails closed on other values. The script defaults to standard, overriding the user config's priority: fast bills ~2.5x credits, and 5.6's long autonomous runs make the burn unpredictable. Delegations are background work; only pass -S fast when the user explicitly asks.

   After the run the script prints the Codex session id; follow up in the same session with codex exec resume <id> "<prompt>". Sessions cannot be named at dispatch (/rename is TUI-only as of codex 0.144) — the id is the handle. Resume only for short follow-ups: gpt-5.6 input past ~272k tokens bills 2x, so a fresh scoped brief beats resuming a long session.

   --dry-run on either prints the filled prompt. run-codex.sh uses codex exec -s workspace-write (OS sandbox caps writes to the worktree); run-claude.sh uses headless claude -p --permission-mode acceptEdits with exactly the standard gate commands allowlisted (a custom -g gate outside that set fails closed — extend the allowlist in the script deliberately, never to bare pnpm:*/cargo:*, which would reopen pnpm exec git / pnpm dlx / cargo run). Claude-side enforcement is policy-level, and the delegate reads the whole repo — instruction-like text anywhere in it is injection surface, so only dispatch onto checkouts you trust. Both runners fail loudly if the delegate moved HEAD.

3. Verify, never trust. Read the diff, re-run the gate yourself, route defects back with evidence (a new brief referencing the old one), then commit.

Gotchas

• Delegate from a clean tracked tree (the runners enforce it; untracked files fail closed unless --allow-untracked) — a dirty base means the delegate can clobber uncommitted work without diff evidence.
• Ignored local files (.env, build outputs, scratch dirs) stay writable by the delegate — inherent to a writable worktree, and the standard flow copies .env in deliberately. Keep unrecoverable local state out of delegated worktrees; re-copy .env from the main checkout if damaged.
• Fresh worktrees need pnpm install --frozen-lockfile before the gate can pass; say so in the brief or run it first.
• codex exec is synchronous — no job babysitting. If dispatching many briefs, run them as background shell tasks and read the -o files.
• The delegate reports what it claims it did; the diff is the truth.

Extending

Add scripts/run-<harness>.sh per scripts/HARNESS-TEMPLATE.md: same CLI, prompt from fill-prompt.sh, write access confined to the worktree, no git mutations, uniform report output.