diff --git a/packages/shared/package.json b/packages/shared/package.json
index 0e29c6c..ce1e22a 100644
--- a/packages/shared/package.json
+++ b/packages/shared/package.json
@@ -7,6 +7,7 @@
   "types": "./src/index.ts",
   "exports": {
     ".": "./src/index.ts",
+    "./model-routing": "./src/model-routing/index.ts",
     "./types": "./src/types/index.ts",
     "./utils": "./src/utils/index.ts"
   },
diff --git a/packages/shared/src/index.ts b/packages/shared/src/index.ts
index 9e03490..f440e17 100644
--- a/packages/shared/src/index.ts
+++ b/packages/shared/src/index.ts
@@ -1,2 +1,3 @@
+export * from "./model-routing";
 export * from "./types";
 export * from "./utils";
diff --git a/packages/shared/src/model-routing/constants.ts b/packages/shared/src/model-routing/constants.ts
new file mode 100644
index 0000000..835386f
--- /dev/null
+++ b/packages/shared/src/model-routing/constants.ts
@@ -0,0 +1,28 @@
+/**
+ * Shipped pipeline defaults — alias *names*, not provider UUIDs. Operators remap
+ * aliases in Settings; these are fallbacks when no workspace route exists.
+ */
+export const PIPELINE_DEFAULT_ROLE_ROUTES: Readonly<Record<string, string>> = {
+  "role-conductor": "claude-planning",
+  "role-architect": "claude-planning",
+  "role-ia-architect": "claude-planning",
+  "role-ux-reviewer": "qwen-coder",
+  "role-implementer": "qwen-coder",
+  "role-reviewer": "qwen-coder",
+  "role-design-system-auditor": "qwen-coder",
+  "role-a11y-auditor": "qwen-coder",
+  "role-doc-writer": "qwen-coder",
+  "gate-copilot": "claude-planning",
+  "chat-default": "qwen-coder",
+};
+
+/** Cursor-era model slugs → registry alias names (workspace may override). */
+export const LEGACY_CURSOR_MODEL_ALIASES: Readonly<Record<string, string>> = {
+  "claude-4.6-opus-high-thinking": "claude-planning",
+  "claude-4.6-sonnet-medium-thinking": "claude-planning",
+  "claude-opus-4-8-thinking-high": "claude-planning",
+  "claude-sonnet-5-thinking-medium": "claude-planning",
+  "composer-2.5-fast": "qwen-coder",
+  "composer-2.5": "qwen-coder",
+  auto: "qwen-coder",
+};
diff --git a/packages/shared/src/model-routing/index.ts b/packages/shared/src/model-routing/index.ts
new file mode 100644
index 0000000..c6fe5ed
--- /dev/null
+++ b/packages/shared/src/model-routing/index.ts
@@ -0,0 +1,28 @@
+export {
+  LEGACY_CURSOR_MODEL_ALIASES,
+  PIPELINE_DEFAULT_ROLE_ROUTES,
+} from "./constants.js";
+export {
+  convoyModelPolicySchema,
+  modelProviderSchema,
+  modelTierSchema,
+  providerTypeSchema,
+  resolvedModelSchema,
+  roleModelRouteSchema,
+  type ConvoyModelPolicy,
+  type ModelProvider,
+  type ModelTier,
+  type ProviderType,
+  type ResolvedModel,
+  type RoleModelRoute,
+} from "./schemas.js";
+export {
+  resolveModel,
+  resolveModelErrorCodeSchema,
+  type ResolveModelError,
+  type ResolveModelErrorCode,
+  type ResolveModelFailure,
+  type ResolveModelInput,
+  type ResolveModelResult,
+  type ResolveModelSuccess,
+} from "./resolve-model.js";
diff --git a/packages/shared/src/model-routing/resolve-model.test.ts b/packages/shared/src/model-routing/resolve-model.test.ts
new file mode 100644
index 0000000..354b49c
--- /dev/null
+++ b/packages/shared/src/model-routing/resolve-model.test.ts
@@ -0,0 +1,172 @@
+import { describe, expect, it } from "vitest";
+
+import { LEGACY_CURSOR_MODEL_ALIASES } from "./constants.js";
+import type { ModelProvider, RoleModelRoute } from "./schemas.js";
+import { resolveModel } from "./resolve-model.js";
+
+const WORKSPACE_ID = "379ecb2f-6db9-4c53-93ad-72c594eb44a5";
+
+function provider(
+  overrides: Partial<ModelProvider> & Pick<ModelProvider, "alias" | "providerType" | "modelId">,
+): ModelProvider {
+  return {
+    id: overrides.id ?? "11111111-1111-1111-1111-111111111111",
+    workspaceId: WORKSPACE_ID,
+    displayName: overrides.displayName ?? overrides.alias,
+    enabled: true,
+    ...overrides,
+  };
+}
+
+const claude = provider({
+  id: "aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa",
+  alias: "claude-planning",
+  providerType: "anthropic",
+  modelId: "claude-sonnet-4-20250514",
+  apiKeyEnvVar: "ANTHROPIC_API_KEY",
+  metadata: { tier: "premium" },
+});
+
+const qwen = provider({
+  id: "bbbbbbbb-bbbb-bbbb-bbbb-bbbbbbbbbbbb",
+  alias: "qwen-coder",
+  providerType: "openai_compatible",
+  modelId: "qwen2.5-coder:32b",
+  baseUrl: "http://127.0.0.1:11434/v1",
+  apiKeyEnvVar: "OLLAMA_API_KEY",
+  metadata: { tier: "local" },
+});
+
+const routes: RoleModelRoute[] = [
+  {
+    id: "cccccccc-cccc-cccc-cccc-cccccccccccc",
+    workspaceId: WORKSPACE_ID,
+    roleId: "role-implementer",
+    providerAliasId: qwen.id,
+    enabled: true,
+  },
+];
+
+const getApiKey = (name: string) =>
+  ({ ANTHROPIC_API_KEY: "sk-ant-test", OLLAMA_API_KEY: "ollama" })[name];
+
+describe("resolveModel", () => {
+  it("prefers brief recommended_model over convoy, workspace, and default", () => {
+    const result = resolveModel({
+      roleId: "role-implementer",
+      providers: [claude, qwen],
+      routes,
+      convoyPolicy: { roles: { "role-implementer": "qwen-coder" } },
+      briefRecommendedModel: "claude-planning",
+      getApiKey,
+    });
+
+    expect(result.ok).toBe(true);
+    if (!result.ok) return;
+    expect(result.source).toBe("brief");
+    expect(result.model.alias).toBe("claude-planning");
+  });
+
+  it("prefers convoy policy over workspace route and pipeline default", () => {
+    const result = resolveModel({
+      roleId: "role-implementer",
+      providers: [claude, qwen],
+      routes,
+      convoyPolicy: { roles: { "role-implementer": "claude-planning" } },
+      getApiKey,
+    });
+
+    expect(result.ok).toBe(true);
+    if (!result.ok) return;
+    expect(result.source).toBe("convoy");
+    expect(result.model.alias).toBe("claude-planning");
+  });
+
+  it("uses workspace route when convoy and brief are absent", () => {
+    const result = resolveModel({
+      roleId: "role-implementer",
+      providers: [claude, qwen],
+      routes,
+      getApiKey,
+    });
+
+    expect(result.ok).toBe(true);
+    if (!result.ok) return;
+    expect(result.source).toBe("workspace");
+    expect(result.model.alias).toBe("qwen-coder");
+    expect(result.model.tier).toBe("local");
+  });
+
+  it("falls back to pipeline default role routes", () => {
+    const result = resolveModel({
+      roleId: "role-architect",
+      providers: [claude, qwen],
+      routes: [],
+      getApiKey,
+    });
+
+    expect(result.ok).toBe(true);
+    if (!result.ok) return;
+    expect(result.source).toBe("default");
+    expect(result.model.alias).toBe("claude-planning");
+  });
+
+  it("returns ALIAS_NOT_RESOLVED when no layer matches", () => {
+    const result = resolveModel({
+      roleId: "role-custom-unknown",
+      providers: [claude, qwen],
+      routes: [],
+      defaultRoutes: {},
+      getApiKey,
+    });
+
+    expect(result.ok).toBe(false);
+    if (result.ok) return;
+    expect(result.error.code).toBe("ALIAS_NOT_RESOLVED");
+  });
+
+  it("returns PROVIDER_DISABLED when alias maps to a disabled provider", () => {
+    const result = resolveModel({
+      roleId: "role-implementer",
+      providers: [{ ...qwen, enabled: false }],
+      routes: [],
+      briefRecommendedModel: "qwen-coder",
+      getApiKey,
+    });
+
+    expect(result.ok).toBe(false);
+    if (result.ok) return;
+    expect(result.error.code).toBe("PROVIDER_DISABLED");
+    expect(result.error.alias).toBe("qwen-coder");
+  });
+
+  it("remaps legacy Cursor model slugs before catalog lookup", () => {
+    const legacySlug = "composer-2.5-fast";
+    expect(LEGACY_CURSOR_MODEL_ALIASES[legacySlug]).toBe("qwen-coder");
+
+    const result = resolveModel({
+      roleId: "role-implementer",
+      providers: [qwen],
+      routes: [],
+      briefRecommendedModel: legacySlug,
+      getApiKey,
+    });
+
+    expect(result.ok).toBe(true);
+    if (!result.ok) return;
+    expect(result.resolvedAlias).toBe("qwen-coder");
+  });
+
+  it("returns API_KEY_MISSING when required env var is absent", () => {
+    const result = resolveModel({
+      roleId: "role-architect",
+      providers: [claude],
+      routes: [],
+      getApiKey: () => undefined,
+    });
+
+    expect(result.ok).toBe(false);
+    if (result.ok) return;
+    expect(result.error.code).toBe("API_KEY_MISSING");
+  });
+});
diff --git a/packages/shared/src/model-routing/resolve-model.ts b/packages/shared/src/model-routing/resolve-model.ts
new file mode 100644
index 0000000..6db25b0
--- /dev/null
+++ b/packages/shared/src/model-routing/resolve-model.ts
@@ -0,0 +1,213 @@
+import {
+  LEGACY_CURSOR_MODEL_ALIASES,
+  PIPELINE_DEFAULT_ROLE_ROUTES,
+} from "./constants.js";
+import type {
+  ConvoyModelPolicy,
+  ModelProvider,
+  ModelTier,
+  ResolvedModel,
+  RoleModelRoute,
+} from "./schemas.js";
+import { resolvedModelSchema } from "./schemas.js";
+
+export const resolveModelErrorCodeSchema = [
+  "ALIAS_NOT_RESOLVED",
+  "PROVIDER_NOT_FOUND",
+  "PROVIDER_DISABLED",
+  "BASE_URL_REQUIRED",
+  "API_KEY_MISSING",
+] as const;
+
+export type ResolveModelErrorCode = (typeof resolveModelErrorCodeSchema)[number];
+
+export type ResolveModelError = {
+  code: ResolveModelErrorCode;
+  message: string;
+  alias?: string;
+  roleId: string;
+};
+
+export type ResolveModelSuccess = {
+  ok: true;
+  model: ResolvedModel;
+  source: "brief" | "convoy" | "workspace" | "default";
+  resolvedAlias: string;
+};
+
+export type ResolveModelFailure = {
+  ok: false;
+  error: ResolveModelError;
+};
+
+export type ResolveModelResult = ResolveModelSuccess | ResolveModelFailure;
+
+export type ResolveModelInput = {
+  roleId: string;
+  providers: ModelProvider[];
+  routes: RoleModelRoute[];
+  convoyPolicy?: ConvoyModelPolicy;
+  briefRecommendedModel?: string;
+  /** Workspace metadata `legacy_model_aliases` — checked after global legacy map. */
+  legacyAliases?: Record<string, string>;
+  getApiKey: (envVarName: string) => string | undefined;
+  defaultRoutes?: Readonly<Record<string, string>>;
+};
+
+function normalizeAlias(
+  rawAlias: string,
+  legacyAliases?: Record<string, string>,
+): string {
+  const trimmed = rawAlias.trim();
+  return (
+    legacyAliases?.[trimmed] ??
+    LEGACY_CURSOR_MODEL_ALIASES[trimmed] ??
+    trimmed
+  );
+}
+
+function readTier(metadata: ModelProvider["metadata"]): ModelTier | undefined {
+  if (!metadata || typeof metadata !== "object") return undefined;
+  const tier = (metadata as { tier?: unknown }).tier;
+  if (
+    tier === "premium" ||
+    tier === "fast" ||
+    tier === "local" ||
+    tier === "auto"
+  ) {
+    return tier;
+  }
+  return undefined;
+}
+
+function pickAlias(
+  input: ResolveModelInput,
+): { alias: string; source: ResolveModelSuccess["source"] } | null {
+  const brief = input.briefRecommendedModel?.trim();
+  if (brief) {
+    return { alias: brief, source: "brief" };
+  }
+
+  const convoyAlias = input.convoyPolicy?.roles?.[input.roleId]?.trim();
+  if (convoyAlias) {
+    return { alias: convoyAlias, source: "convoy" };
+  }
+
+  const route = input.routes.find(
+    (row) => row.roleId === input.roleId && row.enabled,
+  );
+  if (route) {
+    const provider = input.providers.find((p) => p.id === route.providerAliasId);
+    if (provider?.alias) {
+      return { alias: provider.alias, source: "workspace" };
+    }
+  }
+
+  const defaults = input.defaultRoutes ?? PIPELINE_DEFAULT_ROLE_ROUTES;
+  const fallback = defaults[input.roleId]?.trim();
+  if (fallback) {
+    return { alias: fallback, source: "default" };
+  }
+
+  return null;
+}
+
+function fail(
+  code: ResolveModelErrorCode,
+  message: string,
+  roleId: string,
+  alias?: string,
+): ResolveModelFailure {
+  return {
+    ok: false,
+    error: { code, message, roleId, alias },
+  };
+}
+
+/**
+ * Pure resolver — callers load workspace provider/route rows and pass plain
+ * objects. Resolution order: brief → convoy → workspace route → pipeline default.
+ */
+export function resolveModel(input: ResolveModelInput): ResolveModelResult {
+  const picked = pickAlias(input);
+  if (!picked) {
+    return fail(
+      "ALIAS_NOT_RESOLVED",
+      `No model alias resolved for role "${input.roleId}"`,
+      input.roleId,
+    );
+  }
+
+  const resolvedAlias = normalizeAlias(picked.alias, input.legacyAliases);
+  const provider = input.providers.find((p) => p.alias === resolvedAlias);
+  if (!provider) {
+    return fail(
+      "PROVIDER_NOT_FOUND",
+      `Provider alias "${resolvedAlias}" is not registered in this workspace`,
+      input.roleId,
+      resolvedAlias,
+    );
+  }
+
+  if (!provider.enabled) {
+    return fail(
+      "PROVIDER_DISABLED",
+      `Provider alias "${resolvedAlias}" is disabled`,
+      input.roleId,
+      resolvedAlias,
+    );
+  }
+
+  if (provider.providerType === "openai_compatible" && !provider.baseUrl) {
+    return fail(
+      "BASE_URL_REQUIRED",
+      `Provider "${resolvedAlias}" requires baseUrl for openai_compatible`,
+      input.roleId,
+      resolvedAlias,
+    );
+  }
+
+  let apiKey = "";
+  if (provider.apiKeyEnvVar) {
+    const value = input.getApiKey(provider.apiKeyEnvVar);
+    if (value === undefined || value.length === 0) {
+      return fail(
+        "API_KEY_MISSING",
+        `Environment variable "${provider.apiKeyEnvVar}" is not set for provider "${resolvedAlias}"`,
+        input.roleId,
+        resolvedAlias,
+      );
+    }
+    apiKey = value;
+  }
+
+  const model: ResolvedModel = {
+    alias: resolvedAlias,
+    providerType: provider.providerType,
+    modelId: provider.modelId,
+    apiKey,
+    ...(provider.baseUrl ? { baseUrl: provider.baseUrl } : {}),
+    ...(provider.extraHeaders ? { extraHeaders: provider.extraHeaders } : {}),
+    ...(provider.defaultParams ? { defaultParams: provider.defaultParams } : {}),
+    ...(readTier(provider.metadata)
+      ? { tier: readTier(provider.metadata) }
+      : {}),
+  };
+
+  const parsed = resolvedModelSchema.safeParse(model);
+  if (!parsed.success) {
+    return fail(
+      "PROVIDER_NOT_FOUND",
+      parsed.error.issues.map((i) => i.message).join("; "),
+      input.roleId,
+      resolvedAlias,
+    );
+  }
+
+  return {
+    ok: true,
+    model: parsed.data,
+    source: picked.source,
+    resolvedAlias,
+  };
+}
diff --git a/packages/shared/src/model-routing/schemas.ts b/packages/shared/src/model-routing/schemas.ts
new file mode 100644
index 0000000..85a17cb
--- /dev/null
+++ b/packages/shared/src/model-routing/schemas.ts
@@ -0,0 +1,74 @@
+import { z } from "zod";
+
+export const providerTypeSchema = z.enum([
+  "anthropic",
+  "openai",
+  "google",
+  "openai_compatible",
+  "azure_openai",
+]);
+
+export type ProviderType = z.infer<typeof providerTypeSchema>;
+
+export const modelTierSchema = z.enum(["premium", "fast", "local", "auto"]);
+
+export type ModelTier = z.infer<typeof modelTierSchema>;
+
+export const modelProviderSchema = z.object({
+  id: z.string().uuid(),
+  workspaceId: z.string().uuid(),
+  alias: z.string().min(1),
+  displayName: z.string().min(1),
+  providerType: providerTypeSchema,
+  modelId: z.string().min(1),
+  baseUrl: z.string().url().nullable().optional(),
+  apiKeyEnvVar: z.string().min(1).nullable().optional(),
+  extraHeaders: z.record(z.string()).nullable().optional(),
+  defaultParams: z
+    .object({
+      temperature: z.number().optional(),
+      maxTokens: z.number().optional(),
+    })
+    .nullable()
+    .optional(),
+  metadata: z.record(z.unknown()).nullable().optional(),
+  enabled: z.boolean().default(true),
+});
+
+export type ModelProvider = z.infer<typeof modelProviderSchema>;
+
+export const roleModelRouteSchema = z.object({
+  id: z.string().uuid(),
+  workspaceId: z.string().uuid(),
+  roleId: z.string().min(1),
+  providerAliasId: z.string().uuid(),
+  enabled: z.boolean().default(true),
+  sortOrder: z.number().int().optional(),
+});
+
+export type RoleModelRoute = z.infer<typeof roleModelRouteSchema>;
+
+export const resolvedModelSchema = z.object({
+  alias: z.string().min(1),
+  providerType: providerTypeSchema,
+  modelId: z.string().min(1),
+  baseUrl: z.string().url().optional(),
+  apiKey: z.string(),
+  extraHeaders: z.record(z.string()).optional(),
+  defaultParams: z
+    .object({
+      temperature: z.number().optional(),
+      maxTokens: z.number().optional(),
+    })
+    .optional(),
+  tier: modelTierSchema.optional(),
+});
+
+export type ResolvedModel = z.infer<typeof resolvedModelSchema>;
+
+export const convoyModelPolicySchema = z.object({
+  roles: z.record(z.string()).optional(),
+  escalate_to: z.string().min(1).optional(),
+});
+
+export type ConvoyModelPolicy = z.infer<typeof convoyModelPolicySchema>;