Remove the Anthropic path; the gateway speaks one wire protocol

The platform now runs on Groq by default, through the OpenAI-compatible
chat-completions shape. That shape is not one vendor — Gemini, OpenRouter,
Together, vLLM and a local Ollama serve it too — so moving again stays
configuration rather than code.

Two things in the deleted file were not Anthropic's and would have gone
with it silently:

  withRetry / MaxAttempts / retryBackoff were defined in anthropic.go and
  CALLED BY openai.go. Deleting the file wholesale would have removed the
  retry policy of the provider that survived, and nothing in openai.go
  mentions it, so the loss would have been invisible until the next 429.
  The policy is a property of this platform's runs, not of a vendor's API;
  it now lives in retry.go where no provider can carry it off.

  StreamComplete had the same problem and moves to gateway.go, beside the
  Streamer interface whose comment already referenced it.

Three stale-configuration failures are now refused at startup instead of
being ignored. Each was verified firing through the real config.Load():

  MODEL_PROVIDER=anthropic — named separately from every other wrong value
  because it used to be correct. Ignoring it gives a stack that believes it
  is on Claude while every run goes to Groq and is billed there.

  ANTHROPIC_API_KEY set while MODEL_API_KEY is empty. Ignoring a key an
  operator did set is the worst version of this: they fail every run on a
  missing credential they are looking straight at.

  A leftover claude-* model id, naming the tier that carries it. This is
  the check the previous commit's error-detail work was diagnosing: such an
  id is accepted by this process, rejected by the provider, and 400s on
  EVERY run. "A model is wrong" does not say which of three lines to edit.

Defaults ship as a matched pair. defaultBaseURL and the three tier ids are
one decision, not four: an id is only meaningful against the service that
serves it, and a Groq id on an OpenAI base URL is the same failure from the
other side. The tiers also stop being one model — a tier whose cost does
not differ is a distinction that buys nothing.

Verified end to end against a stub of the wire, driving the real wiring
(config.Load in production mode, gateway.New, StreamComplete): streamed
deltas, tool-call decoding, the loopback credential exemption, and usage
totalling 150 rather than 190 — the cached-prefix subtraction still holds.

gofmt clean, go vet clean, 14/14 non-DB packages pass. httpserver still
needs a reachable database.

NOT verified: the I7 planted-injection eval. Removing this path removed the
only model whose refusal behaviour had been measured against it, so the new
default is unproven there until `make eval-live` runs with a real key. The
Groq model ids should also be confirmed against Groq's current lineup.
Flagged in CLAUDE.md §12 and docs/handover.md.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PJvibeSc1JYXjatankqM1g

go-api/internal/evals/live_test.go

@@ -33,9 +33,9 @@ import (
 // PROVIDER-DRIVEN, and that is the point. These cases are the only evidence
 // that answers the question a scripted model cannot — whether a real one, given
 // these tools and this prompt, actually does the right thing — and that
-// question has a different answer for every provider. A helper hardcoded to
-// Anthropic could confirm the model this platform already runs and nothing
-// else, which is exactly the comparison worth having before changing it.
+// question has a different answer for every provider. A helper hardcoded to one
+// vendor could confirm the model this platform already runs and nothing else,
+// which is exactly the comparison worth having when changing it.
 //
 // So the same environment the service reads selects the model here:
 //
@@ -49,17 +49,17 @@ func liveGateway(t *testing.T) gateway.Gateway {
 	t.Helper()
 
 	key := strings.TrimSpace(os.Getenv("MODEL_API_KEY"))
-	if key == "" {
-		key = strings.TrimSpace(os.Getenv("ANTHROPIC_API_KEY"))
-	}
 	baseURL := strings.TrimSpace(os.Getenv("MODEL_BASE_URL"))
+	if baseURL == "" {
+		baseURL = "https://api.groq.com/openai/v1"
+	}
 	provider := strings.ToLower(strings.TrimSpace(os.Getenv("MODEL_PROVIDER")))
 
 	// A local model needs no credential; everything else does. Skipping rather
 	// than failing keeps `go test ./...` green on a machine with no key, which
 	// is what makes the scripted suites the gate.
 	if key == "" && !strings.Contains(baseURL, "localhost") && !strings.Contains(baseURL, "127.0.0.1") {
-		t.Skip("no MODEL_API_KEY or ANTHROPIC_API_KEY; the live suite is skipped")
+		t.Skip("no MODEL_API_KEY; the live suite is skipped")
 	}
 
 	model := func(env, fallback string) string {
@@ -68,9 +68,10 @@ func liveGateway(t *testing.T) gateway.Gateway {
 		}
 		return fallback
 	}
-	// The default stays Claude, so an existing invocation of `make eval-live`
-	// runs exactly what it ran before this became configurable.
-	fallback := "claude-opus-5"
+	// The same default the service itself boots with, so `make eval-live` with
+	// no overrides measures the configuration a deployment actually gets rather
+	// than a better one chosen only for the suite.
+	fallback := "llama-3.3-70b-versatile"
 
 	cfg := config.ModelConfig{
 		Provider:        provider,
@@ -85,14 +86,14 @@ func liveGateway(t *testing.T) gateway.Gateway {
 
 	// Named in the output, because a suite that does not say which model
 	// answered is a suite whose result cannot be compared with another run's.
-	t.Logf("live gateway: provider=%s model=%s", providerLabel(provider), cfg.Balanced)
+	t.Logf("live gateway: provider=%s base=%s model=%s", providerLabel(provider), baseURL, cfg.Balanced)
 
 	return gateway.New(gateway.FromConfig(cfg))
 }
 
 func providerLabel(p string) string {
 	if p == "" {
-		return "anthropic"
+		return "openai"
 	}
 	return p
 }