refactor: move chat error kinds into codersdk (#24955)

Moves the chat error kind taxonomy from `coderd/x/chatd/chaterror` into
`codersdk.ChatErrorKind` and types `ChatError.Kind` /
`ChatStreamRetry.Kind` so generated TypeScript exposes an SDK-owned
union, including `usage_limit`. Backend chat classification now
references the SDK constants directly while preserving the existing JSON
string values.

Keeps chat usage-limit admission failures on their existing 409 response
shape. The frontend maps structured usage-limit responses to the
SDK-owned `usage_limit` kind, uses generated `TypesGen.ChatErrorKind`
directly, and removes the local string union and alias.

coderd/x/chatd/chatloop/chatloop.go

@@ -710,7 +710,7 @@ func classifyStartupTimeout(
 		err = errStartupTimeout
 	}
 	return chaterror.WithClassification(err, chaterror.ClassifiedError{
-		Kind:      chaterror.KindStartupTimeout,
+		Kind:      codersdk.ChatErrorKindStartupTimeout,
 		Provider:  provider,
 		Retryable: true,
 	})

coderd/x/chatd/chatloop/chatloop_test.go

@@ -571,7 +571,7 @@ func TestRun_OnRetryEnrichesProvider(t *testing.T) {
 	require.Equal(t, "received status 429 from upstream", records[0].errMsg)
 	require.Equal(t, chatretry.Delay(0), records[0].delay)
 	require.Equal(t, "openai", records[0].classified.Provider)
-	require.Equal(t, chaterror.KindRateLimit, records[0].classified.Kind)
+	require.Equal(t, codersdk.ChatErrorKindRateLimit, records[0].classified.Kind)
 	require.True(t, records[0].classified.Retryable)
 	require.Equal(t, 429, records[0].classified.StatusCode)
 	require.Equal(
@@ -633,7 +633,7 @@ func TestStartupGuard_DisarmPreservesPermanentError(t *testing.T) {
 		"openai",
 		xerrors.New("invalid model"),
 	))
-	require.Equal(t, chaterror.KindConfig, classified.Kind)
+	require.Equal(t, codersdk.ChatErrorKindConfig, classified.Kind)
 	require.False(t, classified.Retryable)
 	require.Nil(t, context.Cause(attemptCtx))
 }
@@ -700,7 +700,7 @@ func TestRun_RetriesStartupTimeoutWhileOpeningStream(t *testing.T) {
 	require.NoError(t, awaitRunResult(ctx, t, done))
 	require.Equal(t, 2, attempts)
 	require.Len(t, retries, 1)
-	require.Equal(t, chaterror.KindStartupTimeout, retries[0].Kind)
+	require.Equal(t, codersdk.ChatErrorKindStartupTimeout, retries[0].Kind)
 	require.True(t, retries[0].Retryable)
 	require.Equal(t, "openai", retries[0].Provider)
 	require.Equal(
@@ -788,7 +788,7 @@ func TestRun_HTTP2TransportErrorClassifiedAsRetryableTimeout(t *testing.T) {
 			require.NoError(t, awaitRunResult(ctx, t, done))
 			require.Equal(t, 2, attempts)
 			require.Len(t, retries, 1)
-			require.Equal(t, chaterror.KindTimeout, retries[0].Kind, "Kind")
+			require.Equal(t, codersdk.ChatErrorKindTimeout, retries[0].Kind, "Kind")
 			require.True(t, retries[0].Retryable, "Retryable")
 			require.Equal(t, provider, retries[0].Provider, "Provider")
 		})
@@ -862,7 +862,7 @@ func TestRun_RetriesStartupTimeoutBeforeFirstPart(t *testing.T) {
 	require.NoError(t, awaitRunResult(ctx, t, done))
 	require.Equal(t, 2, attempts)
 	require.Len(t, retries, 1)
-	require.Equal(t, chaterror.KindStartupTimeout, retries[0].Kind)
+	require.Equal(t, codersdk.ChatErrorKindStartupTimeout, retries[0].Kind)
 	require.True(t, retries[0].Retryable)
 	require.Equal(t, "openai", retries[0].Provider)
 	require.Equal(
@@ -1077,7 +1077,7 @@ func TestRun_RetriesStartupTimeoutWhenStreamClosesSilently(t *testing.T) {
 	require.NoError(t, awaitRunResult(ctx, t, done))
 	require.Equal(t, 2, attempts)
 	require.Len(t, retries, 1)
-	require.Equal(t, chaterror.KindStartupTimeout, retries[0].Kind)
+	require.Equal(t, codersdk.ChatErrorKindStartupTimeout, retries[0].Kind)
 	require.True(t, retries[0].Retryable)
 	require.Equal(t, "openai", retries[0].Provider)
 	require.Equal(

coderd/x/chatd/chatloop/metrics.go

@@ -145,7 +145,7 @@ func (m *Metrics) RecordStreamRetry(provider, model string, classified chaterror
 	if m == nil {
 		return
 	}
-	m.StreamRetriesTotal.WithLabelValues(provider, model, classified.Kind).Inc()
+	m.StreamRetriesTotal.WithLabelValues(provider, model, string(classified.Kind)).Inc()
 }
 
 // RecordToolError increments tool_errors_total for the given

coderd/x/chatd/chatloop/metrics_test.go

@@ -16,6 +16,7 @@ import (
 	"github.com/coder/coder/v2/coderd/x/chatd/chatloop"
 	"github.com/coder/coder/v2/coderd/x/chatd/chatretry"
 	"github.com/coder/coder/v2/coderd/x/chatd/chattest"
+	"github.com/coder/coder/v2/codersdk"
 )
 
 func TestNewMetrics_RegistersAllMetrics(t *testing.T) {
@@ -33,7 +34,7 @@ func TestNewMetrics_RegistersAllMetrics(t *testing.T) {
 	m.PromptSizeBytes.WithLabelValues("anthropic", "claude-sonnet-4-5")
 	m.TTFTSeconds.WithLabelValues("anthropic", "claude-sonnet-4-5")
 	m.StepsTotal.WithLabelValues("anthropic", "claude-sonnet-4-5")
-	m.StreamRetriesTotal.WithLabelValues("anthropic", "claude-sonnet-4-5", chaterror.KindTimeout)
+	m.StreamRetriesTotal.WithLabelValues("anthropic", "claude-sonnet-4-5", string(codersdk.ChatErrorKindTimeout))
 	// StreamBufferDroppedTotal is a plain Counter, so it's always present
 	// in Gather output once registered; no exerciser call is
 	// needed.
@@ -87,14 +88,14 @@ func TestNopMetrics_DoesNotPanic(t *testing.T) {
 	m.CompactionTotal.WithLabelValues("openai", "gpt-5", "error").Inc()
 	m.CompactionTotal.WithLabelValues("google", "gemini-2.5-pro", "timeout").Inc()
 	m.StepsTotal.WithLabelValues("anthropic", "claude-sonnet-4-5").Inc()
-	m.StreamRetriesTotal.WithLabelValues("anthropic", "claude-sonnet-4-5", chaterror.KindTimeout).Inc()
+	m.StreamRetriesTotal.WithLabelValues("anthropic", "claude-sonnet-4-5", string(codersdk.ChatErrorKindTimeout)).Inc()
 	m.StreamBufferDroppedTotal.Inc()
 
 	// Nil-receiver guard for RecordStreamRetry and
 	// RecordStreamBufferDropped mirrors the existing RecordCompaction nil
 	// guard.
 	var nilMetrics *chatloop.Metrics
-	nilMetrics.RecordStreamRetry("anthropic", "claude-sonnet-4-5", chaterror.ClassifiedError{Kind: chaterror.KindTimeout})
+	nilMetrics.RecordStreamRetry("anthropic", "claude-sonnet-4-5", chaterror.ClassifiedError{Kind: codersdk.ChatErrorKindTimeout})
 	nilMetrics.RecordStreamBufferDropped()
 	nilMetrics.RecordToolError("anthropic", "claude-sonnet-4-5", "test")
 }
@@ -279,21 +280,21 @@ func TestRecordCompaction(t *testing.T) {
 func TestRecordStreamRetry(t *testing.T) {
 	t.Parallel()
 
-	// One row per chaterror.Kind* constant. Production callers always
+	// One row per ChatErrorKind constant. Production callers always
 	// reach RecordStreamRetry through chaterror.Classify, which
 	// guarantees Kind is non-empty, so no empty-string case is
 	// needed.
 	tests := []struct {
 		name string
-		kind string
+		kind codersdk.ChatErrorKind
 	}{
-		{name: "overloaded", kind: chaterror.KindOverloaded},
-		{name: "rate_limit", kind: chaterror.KindRateLimit},
-		{name: "timeout", kind: chaterror.KindTimeout},
-		{name: "startup_timeout", kind: chaterror.KindStartupTimeout},
-		{name: "auth", kind: chaterror.KindAuth},
-		{name: "config", kind: chaterror.KindConfig},
-		{name: "generic", kind: chaterror.KindGeneric},
+		{name: "overloaded", kind: codersdk.ChatErrorKindOverloaded},
+		{name: "rate_limit", kind: codersdk.ChatErrorKindRateLimit},
+		{name: "timeout", kind: codersdk.ChatErrorKindTimeout},
+		{name: "startup_timeout", kind: codersdk.ChatErrorKindStartupTimeout},
+		{name: "auth", kind: codersdk.ChatErrorKindAuth},
+		{name: "config", kind: codersdk.ChatErrorKindConfig},
+		{name: "generic", kind: codersdk.ChatErrorKindGeneric},
 	}
 
 	for _, tt := range tests {
@@ -309,7 +310,7 @@ func TestRecordStreamRetry(t *testing.T) {
 			requireCounter(t, reg, "coderd_chatd_stream_retries_total", 1, map[string]string{
 				"provider": "test-provider",
 				"model":    "test-model",
-				"kind":     tt.kind,
+				"kind":     string(tt.kind),
 			})
 		})
 	}
@@ -558,14 +559,14 @@ func TestRun_StreamRetry_RecordsMetric(t *testing.T) {
 	// Back-compat: OnRetry still fires with classified error.
 	require.Len(t, retries, 1)
 	assert.Equal(t, 1, retries[0].attempt)
-	assert.Equal(t, chaterror.KindRateLimit, retries[0].classified.Kind)
+	assert.Equal(t, codersdk.ChatErrorKindRateLimit, retries[0].classified.Kind)
 	assert.Equal(t, "test-provider", retries[0].classified.Provider)
 
 	// Metric assertion.
 	requireCounter(t, reg, "coderd_chatd_stream_retries_total", 1, map[string]string{
 		"provider": "test-provider",
 		"model":    "test-model",
-		"kind":     chaterror.KindRateLimit,
+		"kind":     string(codersdk.ChatErrorKindRateLimit),
 	})
 }