feat(coder): add model resolution core + multi-batch matcher

Model resolution (from oh-my-openagent/model-core): 6-step priority resolution pipeline (UI select -> user config -> category default -> user fallback -> policy chain -> system default), provider fallback chains, fuzzy model matching, error classification, provider-specific model ID transforms. 14 files, zero runtime deps. Multi-batch matcher (from boocontext-audit): 6 batch types (Observational, Actionable, PreviouslyApplied, Disambiguation, ResponseAnalysis, LowCriticality) for behavioral guideline evaluation. RelationalResolver with iterative convergence (DEPENDS_ON, PRIORITIZES, ENTAILS, TAG_ALL, TAG_PRIORITIZES). SchematicGenerator abstract class with retry and execution plans. 4 files.
2026-06-08 00:17:55 +00:00
parent a7a40c5b46
commit 524a0deaa1
18 changed files with 2191 additions and 0 deletions
--- a/apps/coder/src/services/model-resolution/connected-providers-cache.ts
+++ b/apps/coder/src/services/model-resolution/connected-providers-cache.ts
@@ -0,0 +1,34 @@
+import type { ModelMetadata } from "./provider-cache.js"
+
+export interface ProviderModelsCache {
+  readonly models: Record<string, readonly string[] | readonly ModelMetadata[]>
+  readonly connected: readonly string[]
+  readonly updatedAt: string
+}
+
+export interface ConnectedProvidersAdapter {
+  readConnectedProvidersCache(): string[] | null
+  findProviderModelMetadata(providerID: string, modelID: string): ModelMetadata | undefined
+  readProviderModelsCache(): ProviderModelsCache | null
+}
+
+export function readConnectedProvidersCache(): string[] | null {
+  return null
+}
+
+export function findProviderModelMetadata(
+  _providerID: string,
+  _modelID: string,
+): ModelMetadata | undefined {
+  return undefined
+}
+
+export function readProviderModelsCache(): ProviderModelsCache | null {
+  return null
+}
+
+export const connectedProvidersAdapter: ConnectedProvidersAdapter = {
+  readConnectedProvidersCache,
+  findProviderModelMetadata,
+  readProviderModelsCache,
+}
--- a/apps/coder/src/services/model-resolution/fallback-chain-from-models.ts
+++ b/apps/coder/src/services/model-resolution/fallback-chain-from-models.ts
@@ -0,0 +1,128 @@
+import type { FallbackEntry } from "./model-requirement-types.js"
+import type { FallbackModelObject } from "./fallback-model-object.js"
+import { normalizeFallbackModels } from "./model-resolver.js"
+import { KNOWN_VARIANTS } from "./known-variants.js"
+
+function parseVariantFromModel(rawModel: string): { modelID: string; variant?: string } {
+  if (typeof rawModel !== "string") {
+    return { modelID: "" }
+  }
+  const trimmedModel = rawModel.trim()
+  if (!trimmedModel) {
+    return { modelID: "" }
+  }
+
+  const parenthesizedVariant = trimmedModel.match(/^(.*)\(([^()]+)\)\s*$/)
+  if (parenthesizedVariant) {
+    const modelID = parenthesizedVariant[1]?.trim() ?? ""
+    const variant = parenthesizedVariant[2]?.trim()
+    return variant ? { modelID, variant } : { modelID }
+  }
+
+  const spaceVariant = trimmedModel.match(/^(.*\S)\s+([a-z][a-z0-9_-]*)$/i)
+  if (spaceVariant) {
+    const modelID = spaceVariant[1]?.trim() ?? ""
+    const variant = spaceVariant[2]?.trim().toLowerCase()
+    if (variant && KNOWN_VARIANTS.has(variant)) {
+      return { modelID, variant }
+    }
+  }
+
+  return { modelID: trimmedModel }
+}
+
+export function parseFallbackModelEntry(
+  model: string,
+  contextProviderID: string | undefined,
+  defaultProviderID = "opencode",
+): FallbackEntry | undefined {
+  if (typeof model !== "string") return undefined
+  const trimmed = model.trim()
+  if (!trimmed) return undefined
+
+  const parts = trimmed.split("/")
+  const providerID =
+    parts.length >= 2 ? (parts[0]?.trim() ?? "") : (contextProviderID?.trim() || defaultProviderID)
+  const rawModelID = parts.length >= 2 ? parts.slice(1).join("/").trim() : trimmed
+  if (!providerID || !rawModelID) return undefined
+
+  const parsed = parseVariantFromModel(rawModelID)
+  if (!parsed.modelID) return undefined
+
+  return {
+    providers: [providerID],
+    model: parsed.modelID,
+    variant: parsed.variant,
+  }
+}
+
+export function parseFallbackModelObjectEntry(
+  obj: FallbackModelObject,
+  contextProviderID: string | undefined,
+  defaultProviderID = "opencode",
+): FallbackEntry | undefined {
+  const base = parseFallbackModelEntry(obj.model, contextProviderID, defaultProviderID)
+  if (!base) return undefined
+
+  return {
+    ...base,
+    variant: obj.variant ?? base.variant,
+    reasoningEffort: obj.reasoningEffort,
+    temperature: obj.temperature,
+    top_p: obj.top_p,
+    maxTokens: obj.maxTokens,
+    thinking: obj.thinking,
+  }
+}
+
+/**
+ * Find the most specific FallbackEntry whose `provider/model` is a prefix of
+ * the resolved `provider/modelID`.  Longest match wins so that e.g.
+ * `openai/gpt-5.4-preview` picks the entry for `openai/gpt-5.4-preview` over
+ * the shorter `openai/gpt-5.4`.
+ */
+export function findMostSpecificFallbackEntry(
+  providerID: string,
+  modelID: string,
+  chain: FallbackEntry[],
+): FallbackEntry | undefined {
+  const resolved = `${providerID}/${modelID}`.toLowerCase()
+
+  // Collect entries whose provider/model is a prefix of the resolved model,
+  // together with the length of the matching prefix (longest match wins).
+  const matches: { entry: FallbackEntry; matchLen: number }[] = []
+  for (const entry of chain) {
+    for (const p of entry.providers) {
+      const candidate = `${p}/${entry.model}`.toLowerCase()
+      if (resolved.startsWith(candidate)) {
+        matches.push({ entry, matchLen: candidate.length })
+        break // one match per entry is enough
+      }
+    }
+  }
+
+  if (matches.length === 0) return undefined
+  matches.sort((a, b) => b.matchLen - a.matchLen)
+  return matches[0]!.entry
+}
+
+export function buildFallbackChainFromModels(
+  fallbackModels: string | (string | FallbackModelObject)[] | undefined,
+  contextProviderID: string | undefined,
+  defaultProviderID = "opencode",
+): FallbackEntry[] | undefined {
+  const normalized = normalizeFallbackModels(fallbackModels)
+  if (!normalized || normalized.length === 0) return undefined
+
+  const parsed = normalized
+    .map((entry) => {
+      if (typeof entry === "string") {
+        return parseFallbackModelEntry(entry, contextProviderID, defaultProviderID)
+      }
+      return parseFallbackModelObjectEntry(entry, contextProviderID, defaultProviderID)
+    })
+    .filter((entry): entry is FallbackEntry => entry !== undefined)
+
+  if (parsed.length === 0) return undefined
+  return parsed
+}
--- a/apps/coder/src/services/model-resolution/fallback-model-object.ts
+++ b/apps/coder/src/services/model-resolution/fallback-model-object.ts
@@ -0,0 +1,9 @@
+export type FallbackModelObject = {
+  readonly model: string
+  readonly variant?: string
+  readonly reasoningEffort?: "none" | "minimal" | "low" | "medium" | "high" | "xhigh" | "max"
+  readonly temperature?: number
+  readonly top_p?: number
+  readonly maxTokens?: number
+  readonly thinking?: { readonly type: "enabled" | "disabled"; readonly budgetTokens?: number }
+}
--- a/apps/coder/src/services/model-resolution/index.ts
+++ b/apps/coder/src/services/model-resolution/index.ts
@@ -0,0 +1,80 @@
+export type {
+  FallbackEntry,
+  ModelRequirement,
+} from "./model-requirement-types.js"
+export type {
+  FallbackModelObject,
+} from "./fallback-model-object.js"
+export type {
+  DelegatedModelConfig,
+  ModelResolutionRequest,
+  ModelResolutionProvenance,
+  ModelResolutionResult,
+} from "./model-resolution-types.js"
+export type {
+  ModelResolutionInput,
+  ModelSource,
+  ExtendedModelResolutionInput,
+} from "./model-resolver.js"
+export {
+  resolveModel,
+  resolveModelWithFallback,
+  normalizeFallbackModels,
+  flattenToFallbackModelStrings,
+} from "./model-resolver.js"
+export {
+  normalizeModel,
+  normalizeModelID,
+} from "./model-normalization.js"
+export {
+  fuzzyMatchModel,
+  isModelAvailable,
+} from "./model-availability.js"
+export {
+  transformModelForProvider,
+  transformModelForProviderDisplay,
+} from "./provider-model-id-transform.js"
+export {
+  buildFallbackChainFromModels,
+  parseFallbackModelEntry,
+  parseFallbackModelObjectEntry,
+  findMostSpecificFallbackEntry,
+} from "./fallback-chain-from-models.js"
+export {
+  KNOWN_VARIANTS,
+} from "./known-variants.js"
+export {
+  _setModelResolutionLogImplementationForTesting,
+  resolveModelPipeline,
+} from "./model-resolution-pipeline.js"
+export type {
+  ModelResolutionRequest as PipelineModelResolutionRequest,
+  ModelResolutionProvenance as PipelineModelResolutionProvenance,
+  ModelResolutionResult as PipelineModelResolutionResult,
+  ModelResolutionDeps,
+} from "./model-resolution-pipeline.js"
+export {
+  isRetryableModelError,
+  shouldRetryError,
+  getNextFallback,
+  hasMoreFallbacks,
+  selectFallbackProvider,
+  selectFallbackProviderWithCache,
+} from "./model-error-classifier.js"
+export type {
+  ErrorInfo,
+} from "./model-error-classifier.js"
+export type {
+  ProviderCache,
+  ModelMetadata,
+} from "./provider-cache.js"
+export type {
+  ProviderModelsCache,
+  ConnectedProvidersAdapter,
+} from "./connected-providers-cache.js"
+export {
+  readConnectedProvidersCache,
+  findProviderModelMetadata,
+  readProviderModelsCache,
+  connectedProvidersAdapter,
+} from "./connected-providers-cache.js"
--- a/apps/coder/src/services/model-resolution/known-variants.ts
+++ b/apps/coder/src/services/model-resolution/known-variants.ts
@@ -0,0 +1,16 @@
+/**
+ * Canonical set of recognised variant / effort tokens.
+ * Used by parseFallbackModelEntry (space-suffix detection) and
+ * flattenToFallbackModelStrings (inline-variant stripping).
+ */
+export const KNOWN_VARIANTS = new Set([
+  "low",
+  "medium",
+  "high",
+  "xhigh",
+  "max",
+  "minimal",
+  "none",
+  "auto",
+  "thinking",
+])
--- a/apps/coder/src/services/model-resolution/model-availability.ts
+++ b/apps/coder/src/services/model-resolution/model-availability.ts
@@ -0,0 +1,64 @@
+function normalizeModelName(name: string): string {
+  return name
+    .toLowerCase()
+    .replace(/claude-(opus|sonnet|haiku)-(\d+)[.-](\d+)/g, "claude-$1-$2.$3")
+}
+
+export function fuzzyMatchModel(
+  target: string,
+  available: Set<string>,
+  providers?: string[],
+): string | null {
+  if (available.size === 0) {
+    return null
+  }
+
+  const targetNormalized = normalizeModelName(target)
+
+  let candidates = Array.from(available)
+  if (providers && providers.length > 0) {
+    const providerSet = new Set(providers)
+    candidates = candidates.filter((model) => {
+      const [provider] = model.split("/")
+      return providerSet.has(provider!)
+    })
+  }
+
+  if (candidates.length === 0) {
+    return null
+  }
+
+  const matches = candidates.filter((model) =>
+    normalizeModelName(model).includes(targetNormalized),
+  )
+
+  if (matches.length === 0) {
+    return null
+  }
+
+  const exactMatch = matches.find((model) => normalizeModelName(model) === targetNormalized)
+  if (exactMatch) {
+    return exactMatch
+  }
+
+  const exactModelIdMatches = matches.filter((model) => {
+    const modelId = model.split("/").slice(1).join("/")
+    return normalizeModelName(modelId) === targetNormalized
+  })
+  if (exactModelIdMatches.length > 0) {
+    return exactModelIdMatches.reduce((shortest, current) =>
+      current.length < shortest.length ? current : shortest,
+    )
+  }
+
+  return matches.reduce((shortest, current) =>
+    current.length < shortest.length ? current : shortest,
+  )
+}
+
+export function isModelAvailable(
+  targetModel: string,
+  availableModels: Set<string>,
+): boolean {
+  return fuzzyMatchModel(targetModel, availableModels) !== null
+}
--- a/apps/coder/src/services/model-resolution/model-error-classifier.ts
+++ b/apps/coder/src/services/model-resolution/model-error-classifier.ts
@@ -0,0 +1,261 @@
+import type { FallbackEntry } from "./model-requirement-types.js"
+import type { ProviderCache } from "./provider-cache.js"
+import * as connectedProvidersCache from "./connected-providers-cache.js"
+
+/**
+ * Error names that indicate a retryable model error.
+ * These errors halt execution and should trigger fallback retry.
+ */
+const RETRYABLE_ERROR_NAMES = new Set([
+  "providermodelnotfounderror",
+  "ratelimiterror",
+  "modelunavailableerror",
+  "providerconnectionerror",
+  "authenticationerror",
+])
+
+const STOP_ERROR_NAMES = new Set([
+  "quotaexceedederror",
+  "insufficientcreditserror",
+  "freeusagelimiterror",
+])
+
+/**
+ * Error names that should NOT trigger retry.
+ * These errors are typically user-induced or fixable without switching models.
+ */
+const NON_RETRYABLE_ERROR_NAMES = new Set([
+  "messageabortederror",
+  "permissiondeniederror",
+  "contextlengtherror",
+  "timeouterror",
+  "validationerror",
+  "syntaxerror",
+  "usererror",
+])
+
+/**
+ * Message patterns that indicate a retryable error even without a known error name.
+ */
+const RETRYABLE_MESSAGE_PATTERNS = [
+  "rate_limit",
+  "rate limit",
+  "usage_limit_reached",
+  "usage limit has been reached",
+  "quota",
+  "all credentials for model",
+  "cooling down",
+  "exhausted your capacity",
+  "not found",
+  "unavailable",
+  "insufficient",
+  "too many requests",
+  "over limit",
+  "overloaded",
+  "bad gateway",
+  "bad request",
+  "unknown provider",
+  "provider not found",
+  "model_not_supported",
+  "model not supported",
+  "model is not supported",
+  "connection error",
+  "network error",
+  "timeout",
+  "service unavailable",
+  "internal_server_error",
+  "free usage",
+  "usage exceeded",
+  "credit",
+  "balance",
+  "temporarily unavailable",
+  "try again",
+  "请稍后重试",
+  "503",
+  "502",
+  "504",
+  "429",
+  "529",
+  "selected provider is forbidden",
+  "provider is forbidden",
+  // Chinese retryable patterns (Zhipu, etc.)
+  "频率限制",           // "rate limit"
+  "请求过于频繁",       // "too many requests"
+  "暂时不可用",         // "temporarily unavailable"
+  "服务不可用",         // "service unavailable"
+  "server_error",
+  "an error occurred while processing",
+]
+
+/**
+ * Message patterns that indicate a non-retryable STOP error (quota/billing exhaustion).
+ * These take precedence over RETRYABLE_MESSAGE_PATTERNS.
+ */
+const STOP_MESSAGE_PATTERNS = [
+  "quota will reset after",
+  "quota exceeded",
+  "free usage limit",
+  "billing limit",
+  "billing hard limit",
+  "monthly limit",
+  "plan limit",
+  "subscription quota",
+  "subscription limit",
+  "payment required",
+  "out of credits",
+  "credits exhausted",
+  "insufficient credits",
+  "insufficient balance",
+  "credit balance",
+  "usage limit for this month",
+  "exhausted your capacity",
+  // GLM/Z.ai business error codes that indicate permanent quota/billing exhaustion
+  "daily call limit",
+  "daily limit",
+  "usage limit reached for",
+  "in arrears",
+  "fair use policy",
+  "recharge and try",
+  "使用上限",
+  "额度不足",
+  "余额不足",
+  "已耗尽",
+]
+
+const AUTO_RETRY_GATE_PATTERNS = [
+  "rate limit",
+  "cooling down",
+  "credentials for model",
+]
+
+function hasProviderAutoRetrySignal(message: string): boolean {
+  if (!message.includes("retrying in")) {
+    return false
+  }
+  return AUTO_RETRY_GATE_PATTERNS.some((pattern) => message.includes(pattern))
+}
+
+export interface ErrorInfo {
+  name?: string
+  message?: string
+  /** HTTP status code from the provider response (e.g., 429 for rate limit) */
+  statusCode?: number
+}
+
+/**
+ * Determines if an error is a retryable model error.
+ * Returns true if it's a known retryable type OR matches retryable message patterns.
+ */
+export function isRetryableModelError(error: ErrorInfo): boolean {
+  // If we have an error name, check against known lists
+  if (error.name) {
+    const errorNameLower = error.name.toLowerCase()
+    // Explicit non-retryable takes precedence
+    if (NON_RETRYABLE_ERROR_NAMES.has(errorNameLower)) {
+      return false
+    }
+    if (STOP_ERROR_NAMES.has(errorNameLower)) {
+      return false
+    }
+    // Check if it's a known retryable error
+    if (RETRYABLE_ERROR_NAMES.has(errorNameLower)) {
+      return true
+    }
+  }
+
+  // Check message patterns for unknown errors
+  const msg = error.message?.toLowerCase() ?? ""
+
+  // STOP patterns take precedence over retryable patterns
+  if (STOP_MESSAGE_PATTERNS.some((pattern) => msg.includes(pattern))) {
+    return false
+  }
+
+  if (hasProviderAutoRetrySignal(msg)) {
+    return true
+  }
+
+  // HTTP status code check: catches rate-limit errors regardless of message format/language.
+  // Uses the same codes as runtime-fallback config (400 excluded as it is a permanent client error).
+  if (
+    error.statusCode != null &&
+    (error.statusCode === 429 || error.statusCode === 503 || error.statusCode === 529)
+  ) {
+    return true
+  }
+
+  return RETRYABLE_MESSAGE_PATTERNS.some((pattern) => msg.includes(pattern))
+}
+
+/**
+ * Determines if an error should trigger a fallback retry.
+ * Returns true for errors that halt execution.
+ */
+export function shouldRetryError(error: ErrorInfo): boolean {
+  return isRetryableModelError(error)
+}
+
+/**
+ * Gets the next fallback model from the chain based on attempt count.
+ * Returns undefined if all fallbacks have been exhausted.
+ */
+export function getNextFallback(
+  fallbackChain: FallbackEntry[],
+  attemptCount: number,
+): FallbackEntry | undefined {
+  return fallbackChain[attemptCount]
+}
+
+/**
+ * Checks if there are more fallbacks available after the current attempt.
+ */
+export function hasMoreFallbacks(
+  fallbackChain: FallbackEntry[],
+  attemptCount: number,
+): boolean {
+  return attemptCount < fallbackChain.length
+}
+
+/**
+ * Selects the best provider for a fallback entry.
+ * Priority:
+ * 1) First connected provider in the entry's provider preference order
+ * 2) Preferred provider when connected (and entry providers are unavailable)
+ * 3) First provider listed in the fallback entry
+ */
+export function selectFallbackProvider(
+  providers: string[],
+  preferredProviderID?: string,
+): string {
+  return selectFallbackProviderWithCache(
+    providers,
+    connectedProvidersCache,
+    preferredProviderID,
+  )
+}
+
+export function selectFallbackProviderWithCache(
+  providers: string[],
+  providerCache: ProviderCache,
+  preferredProviderID?: string,
+): string {
+  const connectedProviders = providerCache.readConnectedProvidersCache()
+  if (connectedProviders) {
+    const connectedSet = new Set(connectedProviders.map(p => p.toLowerCase()))
+
+    for (const provider of providers) {
+      if (connectedSet.has(provider.toLowerCase())) {
+        return provider
+      }
+    }
+
+    if (
+      preferredProviderID &&
+      connectedSet.has(preferredProviderID.toLowerCase())
+    ) {
+      return preferredProviderID
+    }
+  }
+
+  return providers[0] ?? preferredProviderID ?? "opencode"
+}
--- a/apps/coder/src/services/model-resolution/model-normalization.ts
+++ b/apps/coder/src/services/model-resolution/model-normalization.ts
@@ -0,0 +1,8 @@
+export function normalizeModel(model?: string): string | undefined {
+  const trimmed = model?.trim()
+  return trimmed || undefined
+}
+
+export function normalizeModelID(modelID: string): string {
+  return modelID.replace(/\.(\d+)/g, "-$1")
+}
--- a/apps/coder/src/services/model-resolution/model-requirement-types.ts
+++ b/apps/coder/src/services/model-resolution/model-requirement-types.ts
@@ -0,0 +1,18 @@
+export type FallbackEntry = {
+  providers: string[];
+  model: string;
+  variant?: string; // Entry-specific variant (e.g., GPT->high, Opus->max)
+  reasoningEffort?: string;
+  temperature?: number;
+  top_p?: number;
+  maxTokens?: number;
+  thinking?: { type: "enabled" | "disabled"; budgetTokens?: number };
+};
+
+export type ModelRequirement = {
+  fallbackChain: FallbackEntry[];
+  variant?: string; // Default variant (used when entry doesn't specify one)
+  requiresModel?: string; // If set, only activates when this model is available (fuzzy match)
+  requiresAnyModel?: boolean; // If true, requires at least ONE model in fallbackChain to be available (or empty availability treated as unavailable)
+  requiresProvider?: string[]; // If set, only activates when any of these providers is connected
+};
--- a/apps/coder/src/services/model-resolution/model-resolution-pipeline.ts
+++ b/apps/coder/src/services/model-resolution/model-resolution-pipeline.ts
@@ -0,0 +1,256 @@
+import { fuzzyMatchModel } from "./model-availability.js"
+import type { FallbackEntry } from "./model-requirement-types.js"
+import { transformModelForProvider } from "./provider-model-id-transform.js"
+import { normalizeModel } from "./model-normalization.js"
+import type { ProviderCache } from "./provider-cache.js"
+
+type LogImplementation = (message: string, data?: unknown) => void
+
+let logImplementationForTesting: LogImplementation | undefined
+
+function log(message: string, data?: unknown): void {
+  const logImpl = logImplementationForTesting
+  if (!logImpl) {
+    return
+  }
+  if (arguments.length === 1) {
+    logImpl(message)
+    return
+  }
+  logImpl(message, data)
+}
+
+export function _setModelResolutionLogImplementationForTesting(
+  logImplementation: LogImplementation | undefined,
+): void {
+  logImplementationForTesting = logImplementation
+}
+
+export type ModelResolutionRequest = {
+  intent?: {
+    uiSelectedModel?: string
+    userModel?: string
+    userFallbackModels?: string[]
+    categoryDefaultModel?: string
+  }
+  constraints: {
+    availableModels: Set<string>
+    connectedProviders?: string[] | null
+  }
+  policy?: {
+    fallbackChain?: FallbackEntry[]
+    systemDefaultModel?: string
+  }
+}
+
+export type ModelResolutionProvenance =
+  | "override"
+  | "category-default"
+  | "provider-fallback"
+  | "system-default"
+
+export type ModelResolutionResult = {
+  model: string
+  provenance: ModelResolutionProvenance
+  variant?: string
+  attempted?: string[]
+  reason?: string
+}
+
+export type ModelResolutionDeps = {
+  fuzzyMatchModel: (
+    target: string,
+    available: Set<string>,
+    providers?: string[],
+  ) => string | null
+  transformModelForProvider: (provider: string, model: string) => string
+}
+
+const DEFAULT_MODEL_RESOLUTION_DEPS: ModelResolutionDeps = {
+  fuzzyMatchModel,
+  transformModelForProvider,
+}
+
+
+export function resolveModelPipeline(
+  request: ModelResolutionRequest,
+  providerCache: ProviderCache = {
+    readConnectedProvidersCache: () => null,
+    findProviderModelMetadata: () => undefined,
+  },
+  deps: ModelResolutionDeps = DEFAULT_MODEL_RESOLUTION_DEPS,
+): ModelResolutionResult | undefined {
+  const attempted: string[] = []
+  const { intent, constraints, policy } = request
+  const availableModels = constraints.availableModels
+  const fallbackChain = policy?.fallbackChain
+  const systemDefaultModel = policy?.systemDefaultModel
+
+  const normalizedUiModel = normalizeModel(intent?.uiSelectedModel)
+  if (normalizedUiModel) {
+    log("Model resolved via UI selection", { model: normalizedUiModel })
+    return { model: normalizedUiModel, provenance: "override" }
+  }
+
+  const normalizedUserModel = normalizeModel(intent?.userModel)
+  if (normalizedUserModel) {
+    log("Model resolved via config override", { model: normalizedUserModel })
+    return { model: normalizedUserModel, provenance: "override" }
+  }
+
+  const normalizedCategoryDefault = normalizeModel(intent?.categoryDefaultModel)
+  if (normalizedCategoryDefault) {
+    attempted.push(normalizedCategoryDefault)
+    if (availableModels.size > 0) {
+      const parts = normalizedCategoryDefault.split("/")
+      const providerHint = parts.length >= 2 ? [parts[0]!] : undefined
+      const match = deps.fuzzyMatchModel(normalizedCategoryDefault, availableModels, providerHint)
+      if (match) {
+        log("Model resolved via category default (fuzzy matched)", {
+          original: normalizedCategoryDefault,
+          matched: match,
+        })
+        return { model: match, provenance: "category-default", attempted }
+      }
+    } else {
+      const connectedProviders = constraints.connectedProviders ?? providerCache.readConnectedProvidersCache()
+      if (connectedProviders === null) {
+        log("Model resolved via category default (no cache, first run)", {
+          model: normalizedCategoryDefault,
+        })
+        return { model: normalizedCategoryDefault, provenance: "category-default", attempted }
+      }
+      const parts = normalizedCategoryDefault.split("/")
+      if (parts.length >= 2) {
+        const provider = parts[0]!
+        if (connectedProviders.includes(provider)) {
+          const modelName = parts.slice(1).join("/")
+          const transformedModel = `${provider}/${deps.transformModelForProvider(provider, modelName)}`
+          log("Model resolved via category default (connected provider)", {
+            model: transformedModel,
+            original: normalizedCategoryDefault,
+          })
+          return { model: transformedModel, provenance: "category-default", attempted }
+        }
+      }
+    }
+    log("Category default model not available, falling through to fallback chain", {
+      model: normalizedCategoryDefault,
+    })
+  }
+
+  //#when - user configured fallback_models, try them before hardcoded fallback chain
+  const userFallbackModels = intent?.userFallbackModels
+  if (userFallbackModels && userFallbackModels.length > 0) {
+    if (availableModels.size === 0) {
+      const connectedProviders = constraints.connectedProviders ?? providerCache.readConnectedProvidersCache()
+      const connectedSet = connectedProviders ? new Set(connectedProviders) : null
+
+      if (connectedSet !== null) {
+        for (const model of userFallbackModels) {
+          attempted.push(model)
+          const parts = model.split("/")
+          if (parts.length >= 2) {
+            const provider = parts[0]!
+            if (connectedSet.has(provider)) {
+              const modelName = parts.slice(1).join("/")
+              const transformedModel = `${provider}/${deps.transformModelForProvider(provider, modelName)}`
+              log("Model resolved via user fallback_models (connected provider)", { model: transformedModel, original: model })
+              return { model: transformedModel, provenance: "provider-fallback", attempted }
+            }
+          }
+        }
+        log("No connected provider found in user fallback_models, falling through to hardcoded chain")
+      }
+    } else {
+      for (const model of userFallbackModels) {
+        attempted.push(model)
+        const parts = model.split("/")
+        const providerHint = parts.length >= 2 ? [parts[0]!] : undefined
+        const match = deps.fuzzyMatchModel(model, availableModels, providerHint)
+        if (match) {
+          log("Model resolved via user fallback_models (availability confirmed)", { model, match })
+          return { model: match, provenance: "provider-fallback", attempted }
+        }
+      }
+      log("No available model found in user fallback_models, falling through to hardcoded chain")
+    }
+  }
+
+  if (fallbackChain && fallbackChain.length > 0) {
+    if (availableModels.size === 0) {
+      const connectedProviders = constraints.connectedProviders ?? providerCache.readConnectedProvidersCache()
+      const connectedSet = connectedProviders ? new Set(connectedProviders) : null
+
+      if (connectedSet === null) {
+        log("Model fallback chain skipped (no connected providers cache) - falling through to system default")
+      } else {
+        for (const entry of fallbackChain) {
+          for (const provider of entry.providers) {
+            if (connectedSet.has(provider)) {
+              const transformedModelId = deps.transformModelForProvider(provider, entry.model)
+              const model = `${provider}/${transformedModelId}`
+              log("Model resolved via fallback chain (connected provider)", {
+                provider,
+                model: transformedModelId,
+                variant: entry.variant,
+              })
+              return {
+                model,
+                provenance: "provider-fallback",
+                variant: entry.variant,
+                attempted,
+              }
+            }
+          }
+        }
+        log("No connected provider found in fallback chain, falling through to system default")
+      }
+    } else {
+      for (const entry of fallbackChain) {
+        for (const provider of entry.providers) {
+          const fullModel = `${provider}/${entry.model}`
+          const match = deps.fuzzyMatchModel(fullModel, availableModels, [provider])
+          if (match) {
+            log("Model resolved via fallback chain (availability confirmed)", {
+              provider,
+              model: entry.model,
+              match,
+              variant: entry.variant,
+            })
+            return {
+              model: match,
+              provenance: "provider-fallback",
+              variant: entry.variant,
+              attempted,
+            }
+          }
+        }
+
+        const crossProviderMatch = deps.fuzzyMatchModel(entry.model, availableModels)
+        if (crossProviderMatch) {
+          log("Model resolved via fallback chain (cross-provider fuzzy match)", {
+            model: entry.model,
+            match: crossProviderMatch,
+            variant: entry.variant,
+          })
+          return {
+            model: crossProviderMatch,
+            provenance: "provider-fallback",
+            variant: entry.variant,
+            attempted,
+          }
+        }
+      }
+      log("No available model found in fallback chain, falling through to system default")
+    }
+  }
+
+  if (systemDefaultModel === undefined) {
+    log("No model resolved - systemDefaultModel not configured")
+    return undefined
+  }
+
+  log("Model resolved via system default", { model: systemDefaultModel })
+  return { model: systemDefaultModel, provenance: "system-default", attempted }
+}
--- a/apps/coder/src/services/model-resolution/model-resolution-types.ts
+++ b/apps/coder/src/services/model-resolution/model-resolution-types.ts
@@ -0,0 +1,41 @@
+import type { FallbackEntry } from "./model-requirement-types.js"
+
+export interface DelegatedModelConfig {
+  providerID: string
+  modelID: string
+  variant?: string
+  reasoningEffort?: string
+  temperature?: number
+  top_p?: number
+  maxTokens?: number
+  thinking?: { type: "enabled" | "disabled"; budgetTokens?: number }
+}
+
+export type ModelResolutionRequest = {
+  intent?: {
+    uiSelectedModel?: string
+    userModel?: string
+    categoryDefaultModel?: string
+  }
+  constraints: {
+    availableModels: Set<string>
+  }
+  policy?: {
+    fallbackChain?: FallbackEntry[]
+    systemDefaultModel?: string
+  }
+}
+
+export type ModelResolutionProvenance =
+  | "override"
+  | "category-default"
+  | "provider-fallback"
+  | "system-default"
+
+export type ModelResolutionResult = {
+  model: string
+  provenance: ModelResolutionProvenance
+  variant?: string
+  attempted?: string[]
+  reason?: string
+}
--- a/apps/coder/src/services/model-resolution/model-resolver.ts
+++ b/apps/coder/src/services/model-resolution/model-resolver.ts
@@ -0,0 +1,109 @@
+import type { FallbackEntry } from "./model-requirement-types.js"
+import type { FallbackModelObject } from "./fallback-model-object.js"
+import { normalizeModel } from "./model-normalization.js"
+import { resolveModelPipeline } from "./model-resolution-pipeline.js"
+import { KNOWN_VARIANTS } from "./known-variants.js"
+import type { ConnectedProvidersAdapter } from "./connected-providers-cache.js"
+import * as connectedProvidersCache from "./connected-providers-cache.js"
+
+export type ModelResolutionInput = {
+  userModel?: string
+  inheritedModel?: string
+  systemDefault?: string
+}
+
+export type ModelSource =
+  | "override"
+  | "category-default"
+  | "provider-fallback"
+  | "system-default"
+
+export type ModelResolutionResult = {
+  model: string
+  source: ModelSource
+  variant?: string
+}
+
+export type ExtendedModelResolutionInput = {
+  uiSelectedModel?: string
+  userModel?: string
+  userFallbackModels?: string[]
+  categoryDefaultModel?: string
+  fallbackChain?: FallbackEntry[]
+  availableModels: Set<string>
+  systemDefaultModel?: string
+}
+
+
+export function resolveModel(input: ModelResolutionInput): string | undefined {
+  return (
+    normalizeModel(input.userModel) ??
+    normalizeModel(input.inheritedModel) ??
+    input.systemDefault
+  )
+}
+
+export function resolveModelWithFallback(
+  input: ExtendedModelResolutionInput,
+  connectedProvidersAdapter: ConnectedProvidersAdapter = connectedProvidersCache,
+): ModelResolutionResult | undefined {
+  const { uiSelectedModel, userModel, userFallbackModels, categoryDefaultModel, fallbackChain, availableModels, systemDefaultModel } = input
+  const resolved = resolveModelPipeline({
+    intent: { uiSelectedModel, userModel, userFallbackModels, categoryDefaultModel },
+    constraints: { availableModels },
+    policy: { fallbackChain, systemDefaultModel },
+  }, connectedProvidersAdapter)
+
+  if (!resolved) {
+    return undefined
+  }
+
+  return {
+    model: resolved.model,
+    source: resolved.provenance,
+    variant: resolved.variant,
+  }
+}
+
+/**
+ * Normalizes fallback_models config to a mixed array.
+ * Accepts string, string[], or mixed arrays of strings and FallbackModelObject entries.
+ */
+export function normalizeFallbackModels(
+  models: string | (string | FallbackModelObject)[] | undefined,
+): (string | FallbackModelObject)[] | undefined {
+  if (!models) return undefined
+  if (typeof models === "string") return [models]
+  return models
+}
+
+/**
+ * Extracts plain model strings from a mixed fallback models array.
+ * Object entries are flattened to "model" or "model(variant)" strings.
+ * Use this when consumers need string[] (e.g., resolveModelForDelegateTask).
+ */
+export function flattenToFallbackModelStrings(
+  models: (string | FallbackModelObject)[] | undefined,
+): string[] | undefined {
+  if (!models) return undefined
+  return models.map((entry) => {
+    if (typeof entry === "string") return entry
+    const variant = entry.variant
+    if (variant) {
+      // Strip any supported inline variant syntax before appending explicit override.
+      // Supports both parenthesized and space-suffix forms so we don't emit
+      // invalid strings like "provider/model high(low)".
+      const model = entry.model
+        .replace(/\([^()]+\)\s*$/, "")
+        .replace(/\s+([a-z][a-z0-9_-]*)\s*$/i, (_match: string, suffix: string) => {
+          const normalized = String(suffix).toLowerCase()
+          return KNOWN_VARIANTS.has(normalized)
+            ? ""
+            : _match
+        })
+        .trim()
+      return `${model}(${variant})`
+    }
+    return entry.model
+  })
+}
--- a/apps/coder/src/services/model-resolution/provider-cache.ts
+++ b/apps/coder/src/services/model-resolution/provider-cache.ts
@@ -0,0 +1,27 @@
+export interface ModelMetadata {
+  readonly id: string
+  readonly provider?: string
+  readonly context?: number
+  readonly output?: number
+  readonly name?: string
+  readonly variants?: Record<string, unknown>
+  readonly limit?: {
+    readonly context?: number
+    readonly input?: number
+    readonly output?: number
+  }
+  readonly modalities?: {
+    readonly input?: string[]
+    readonly output?: string[]
+  }
+  readonly capabilities?: Record<string, unknown>
+  readonly reasoning?: boolean
+  readonly temperature?: boolean
+  readonly tool_call?: boolean
+  readonly [key: string]: unknown
+}
+
+export interface ProviderCache {
+  readConnectedProvidersCache(): string[] | null
+  findProviderModelMetadata(providerID: string, modelID: string): ModelMetadata | undefined
+}
--- a/apps/coder/src/services/model-resolution/provider-model-id-transform.ts
+++ b/apps/coder/src/services/model-resolution/provider-model-id-transform.ts
@@ -0,0 +1,69 @@
+function inferSubProvider(model: string): string | undefined {
+  if (model.startsWith("claude-")) return "anthropic"
+  if (model.startsWith("gpt-")) return "openai"
+  if (model.startsWith("gemini-")) return "google"
+  if (model.startsWith("grok-")) return "xai"
+  if (model.startsWith("minimax-")) return "minimax"
+  if (model.startsWith("kimi-")) return "moonshotai"
+  if (model.startsWith("glm-")) return "zai"
+  return undefined
+}
+
+const CLAUDE_VERSION_DOT = /claude-(\w+)-(\d+)-(\d+)/g
+const GEMINI_31_PRO_PREVIEW = /gemini-3\.1-pro(?!-)/g
+const GEMINI_3_FLASH_PREVIEW = /gemini-3-flash(?!-)/g
+
+function claudeVersionDot(model: string): string {
+  return model.replace(CLAUDE_VERSION_DOT, "claude-$1-$2.$3")
+}
+
+function applyGatewayTransforms(model: string): string {
+  return claudeVersionDot(model).replace(
+    GEMINI_31_PRO_PREVIEW,
+    "gemini-3.1-pro-preview",
+  )
+}
+
+function transformModelForProviderUsingAnthropicBehavior(
+  provider: string,
+  model: string,
+): string {
+  if (provider === "vercel") {
+    const slashIndex = model.indexOf("/")
+    if (slashIndex !== -1) {
+      const subProvider = model.substring(0, slashIndex)
+      const subModel = model.substring(slashIndex + 1)
+      return `${subProvider}/${applyGatewayTransforms(subModel)}`
+    }
+    const subProvider = inferSubProvider(model)
+    if (subProvider) {
+      return `${subProvider}/${applyGatewayTransforms(model)}`
+    }
+    return model
+  }
+  if (provider === "github-copilot") {
+    return claudeVersionDot(model)
+      .replace(GEMINI_31_PRO_PREVIEW, "gemini-3.1-pro-preview")
+      .replace(GEMINI_3_FLASH_PREVIEW, "gemini-3-flash-preview")
+  }
+  if (provider === "google") {
+    return model
+      .replace(GEMINI_31_PRO_PREVIEW, "gemini-3.1-pro-preview")
+      .replace(GEMINI_3_FLASH_PREVIEW, "gemini-3-flash-preview")
+  }
+  if (provider === "anthropic") {
+    return model
+  }
+  return model
+}
+
+export function transformModelForProvider(provider: string, model: string): string {
+  return transformModelForProviderUsingAnthropicBehavior(provider, model)
+}
+
+export function transformModelForProviderDisplay(
+  provider: string,
+  model: string,
+): string {
+  return transformModelForProviderUsingAnthropicBehavior(provider, model)
+}