Fix: Refuse a non-USD unit on a pricing block for every endpoint

[huang195]

Summary

Fixes #1190. A pricing block with a non-USD unit: and no hosts: (or "*" among them) now fails startup, beside the existing refusal for a unit on a multiplier-only block.

Why: after #1153 a unit is host-wide. Table.unitFor gives an endpoint the unit of its best-ranked row, and only rows in that unit may price its traffic. So a catch-all block with a unit puts every endpoint that no more specific block names into that unit:

• the bundled dollar table prices nothing there. This is loud, because unpricedBy names every pair;
• every charge those endpoints report themselves is labelled in that unit. This one is silent.

Measured in the issue at 80348bf with hosts: ["*"], unit: credits and the bundled table on: api.anthropic.com claude-opus-4-1 went from unit=USD prov=bundled to unit=credits prov=none.

A unit belongs to one gateway, so that gateway's hosts can be named. The error names the block:

pricing.endpoints[0] (hosts [*]): unit "credits" needs hosts naming the gateways that bill in it; a block for every endpoint would put all of them in that unit

Changes

• core/cost/pricing/config.go: Config.entries refuses a block whose unit is not USD and whose hosts include a catch-all (anyHost: "" or "*"). The check covers a catch-all anywhere in the list, since ["gw.bob", "*"] still covers every endpoint. Any spelling of USD ("", usd) is accepted, because it is no unit claim. This matches the multiplier-only refusal.
• core/cost/pricing/config_test.go:
  • new TestConfig_AUnitOnACatchAllBlockIsRefused, a sibling of TestConfig_AUnitOnAMultiplierOnlyBlockIsRefused:
    • refused: no hosts, ["*"], ["gw.bob", "*"];
    • accepted: hostless "" / usd, ["*"] with USD, a named gateway with credits.
  • removed the "any-endpoint spelled two ways" case from TestConfig_BlocksForOneHostMustAgreeOnTheUnit. It paired a hostless credits block with a "*" USD one. Since a catch-all can no longer carry a unit, two spellings of it always agree, and the new refusal fires first. A comment on the test now points at the new one.
• docs/pricing.md: the Billing units section lists this refusal beside the other two.

Unaffected: the built-in local config's Bob entry (cmd/cortex/local.go) and agentop config migrate-pricing both name api.us-east.bob.ibm.com.

Test plan

• The new test fails on unmodified main (all three refusal cases build successfully there).
• Mutation-checked: a predicate that refuses only hostless blocks (len(ep.Hosts) == 0) fails the ["*"] and ["gw.bob", "*"] cases.
• go test ./... in core; GOWORK=off go test ./... in cmd/cortex and cmd/agentop (with SSL_CERT_FILE unset). go vet ./cost/... and gofmt -l ./cost clean.

Assisted-By: Claude (Anthropic AI) noreply@anthropic.com

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📥 Commits

Reviewing files that changed from the base of the PR and between ccb33e4 and 310d4cc.

📒 Files selected for processing (3)

• core/cost/pricing/config.go
• core/cost/pricing/config_test.go
• docs/pricing.md

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[mrsabath]

Verified the mechanism this guards against: Table.unitFor ranks provenance first, so a configured catch-all row with a unit does outrank the bundled USD rows and would relabel every endpoint no more specific block names — the failure in #1190 is real, not theoretical.

The check is correctly placed after the len(ep.Models) == 0 branch, so it cannot collide with the multiplier-only refusal (that path continues first). slices.ContainsFunc over the normalised hosts catches both the hostless case and "*" anywhere in the list, and EqualFold against CurrencyUSD after normaliseUnit means no spelling of the default is treated as a unit claim. Echoing ep.Unit rather than the normalised value in the error is the right call — it shows the operator what they typed.

Confirmed the "unaffected" claim: cmd/cortex/local.go and cmd_config_migrate_pricing.go both name api.us-east.bob.ibm.com, and the only unit: example in docs/pricing.md names a concrete host — so nothing shipped or documented regresses. The removed "any-endpoint spelled two ways" case is genuinely subsumed, and it left a pointer to the new test behind rather than vanishing. The mutation check in the test plan (a len(ep.Hosts) == 0-only predicate failing the ["*"] cases) is exactly the right thing to verify for this predicate.

No must-fix issues, and nothing I would raise as a suggestion either.

Areas reviewed: Go (core/cost/pricing), tests, docs
Commits: 1, signed off
CI status: passing (28 checks, Spellcheck skipped)