/copilot

name: github:copilot
description: Get a cross-model second opinion on a code change from GPT via the Copilot CLI, then triage what it finds. Use when the ask names GPT, Copilot, a second model, or a cross-model check, and as the cross-model pass on a change that clears the review gate.
argument-hint: "[--base <ref>] [--angles <n>] [--model <name>] [--agentic] [--status] [--dry-run] [--max-bytes <n>] [--force]"
allowed-tools:
  - Bash(bun ${CLAUDE_PLUGIN_ROOT}/skills/copilot/scripts/review.ts:*)
  - Bash(git diff:*)
  - Bash(git log:*)
  - Bash(git status:*)
  - Read
  - Grep
  - Glob
  - Edit

Copilot Review

A second model reads the diff. The point is a different reviewer rather than a better one: Claude re-reading its own work shares the blind spot that produced it. It has already caught an unchecked-failure defect that two Claude review passes both cleared.

What It Costs

The plan grants 1500 AI credits a month. It resets on the 1st and does not roll over. Four measured facts shape every choice:

• A terra call pays about 3.5 credits before it reads a line of your code, writing 14k tokens of system prompt and tool definitions to cache at 250 credits per million. That is half a median review. A second call is never a rounding error.
• Output costs 6x input and 60x cache_read. Verbose answers run up a bill faster than large diffs.
• Nothing caches between calls. Separate spawns are separate sessions, and each one re-pays its whole prompt at the cache_write rate. Three angles cost three full prompts.
• `gpt-5.6-luna` prices every token class at exactly a tenth of terra.

Sizing a Review

`--status` prints the current tier and the bands, and spends nothing. Run it when you are unsure whether a change qualifies.

The tier comes from `pace`, credits remaining divided by days to reset. Under 25 is constrained, over 60 is abundant, and everything between is normal. The nominal allowance of 48 a day (1500 over 31) is the yardstick `--status` prints `pace` against, and it decides nothing on its own. The tier sets how strict the bar is, never how much to spend. Manufacturing reviews to use up an allotment is the failure mode this guards against, so credits left unspent in a month where every qualifying change got a full review are the right outcome.

| tier | gate | | --- | --- | | constrained | terra only on risk-surface hits, luna one-shot otherwise | | normal | terra one-shot on gate-worthy changes, skip the rest | | abundant | terra one-shot on any substantial human change, 3 angles on the risk class, agentic available |

The bands reuse ship's Bot Review Gate criteria, so one set of rules decides both:

| band | criteria | shape | cost | | --- | --- | --- | --- | | skip | bot bumps, prose, lockfiles, reverts, config away from the risk surfaces | none | 0 | | deep | a runtime surface, auth, sandbox, permissions, secrets, or egress; over ~200 lines or 8 files excluding tests, docs, and lockfiles; a bug `review:code` confirmed; a session that drifted | terra, 1 angle | 7.6-12.4 | | deep+ | risk-surface hits, abundant tier only | terra, 3 angles | ~22.7 | | agentic | destructive, concurrent, or auth changes, abundant tier only | capped session | up to 60 |

The script enforces the hard stops on its own. It refuses `--agentic` outside the abundant tier, degrades to luna below 150 credits remaining, and refuses any run whose session cap could carry the account into billed overage. A meter it cannot read stops the run, which is what keeps this inert on a machine with no personal Copilot entitlement.

Arguments

Everything is optional and forwards to the script.

• `--base <ref>`: what to diff against. Defaults to the upstream tracking ref, then `origin/main`.
• `--angles <1-3>`: independent review calls. Defaults to 1. See [Angles](#angles).
• `--model <name>`: see [Models](#models). Defaults to `gpt-5.6-terra`.
• `--agentic`: review from a disposable checkout with tools instead of from inlined text. It is one capped session and refuses `--angles` above 1. See [Agentic Mode](#agentic-mode).
• `--status`: print the tier and bands, spend nothing.
• `--dry-run`: print the assembled prompts and their size, spend nothing.
• `--max-bytes <n>`: raise or lower the 120 KB prompt cap.
• `--force`: run even when a prompt exceeds the size cap.

Run It

bun ${CLAUDE_PLUGIN_ROOT}/skills/copilot/scripts/review.ts [--base <ref>] [--angles <n>] [--model <name>]

The script resolves the diff, inlines the changed files, and prints each angle's findings with what it spent and what is left. It refuses a prompt over 120 KB rather than quietly spending on it. Prefer narrowing with `--base`, then `--max-bytes`, over passing `--force`.

Angles

One angle asks for every defect class in one call, which is the right default. Above that, the script splits the classes so the calls do not overlap, because three identical reviews mostly agree and cost three times as much for one review's worth of coverage.

| angles | coverage | | --- | --- | | 1 | every class, one call | | 2 | unchecked failure and correctness, then data loss and security | | 3 | adds contracts, concurrency, and resources |

Use 3 only for something security-sensitive, destructive, or concurrent, and only in the abundant tier. It triples the spend and buys no cache discount.

Agentic Mode

`--agentic` gives Copilot a throwaway `git worktree` checked out at HEAD and lets it use tools. It reads callers, tests, and history instead of only what the prompt carries. That is its one categorical advantage. It runs under a 60-credit cap against a one-shot's 30, and a one-shot in practice lands at 7.6 to 12.4, so budget for several times the cost rather than double. It needs a clean tree, because a worktree at HEAD would otherwise show it code that does not match the diff it was handed.

Reserve it for changes you authored. A diff carrying untrusted third-party text gets the one-shot shape, where the model has no tools and cannot