diff --git a/.devcontainer/devcontainer.json b/.devcontainer/devcontainer.json
new file mode 100644
index 00000000..e2be7d74
--- /dev/null
+++ b/.devcontainer/devcontainer.json
@@ -0,0 +1,14 @@
+{
+  "name": "opencode-dev",
+  "image": "mcr.microsoft.com/devcontainers/base:ubuntu",
+  "features": {
+    "ghcr.io/devcontainers/features/node:1": {}
+  },
+  "postCreateCommand": "curl -fsSL https://bun.sh/install | bash && echo 'export PATH=\"$HOME/.bun/bin:$PATH\"' >> ~/.bashrc",
+  "customizations": {
+    "vscode": {
+      "extensions": ["dbaeumer.vscode-eslint"]
+    }
+  }
+}
+
diff --git a/packages/opencode/src/cli/error.ts b/packages/opencode/src/cli/error.ts
index 407547e4..1a71170c 100644
--- a/packages/opencode/src/cli/error.ts
+++ b/packages/opencode/src/cli/error.ts
@@ -4,6 +4,8 @@ import { isRecord } from "@/util/record"
 
 type ConfigIssue = { message: string; path: string[] }
 
+type ErrorFormatter = (input: unknown) => string | undefined
+
 function isTaggedError(error: unknown, tag: string): error is Record<string, unknown> {
   return isRecord(error) && error._tag === tag
 }
@@ -32,99 +34,129 @@ function configIssues(input: Record<string, unknown>): ConfigIssue[] {
     : []
 }
 
-export function FormatError(input: unknown): string | undefined {
-  if (input instanceof Error && isRecord(input.cause) && "body" in input.cause) {
-    const formatted = FormatError(input.cause.body)
-    if (formatted) return formatted
-  }
+// CliError: domain failure surfaced from an effectCmd handler via fail("...")
+function formatCliError(input: unknown): string | undefined {
+  if (!isTaggedError(input, "CliError")) return undefined
+  if (typeof input.exitCode === "number") process.exitCode = input.exitCode
+  return stringField(input, "message") ?? ""
+}
 
-  // CliError: domain failure surfaced from an effectCmd handler via fail("...")
-  if (isTaggedError(input, "CliError")) {
-    if (typeof input.exitCode === "number") process.exitCode = input.exitCode
-    return stringField(input, "message") ?? ""
-  }
+// MCPFailed: { name: string }
+function formatMcpFailed(input: unknown): string | undefined {
+  if (!NamedError.hasName(input, "MCPFailed")) return undefined
+  const data = isRecord(input) && isRecord(input.data) ? stringField(input.data, "name") : undefined
+  return `MCP server "${data}" failed. Note, opencode does not support MCP authentication yet.`
+}
 
-  // MCPFailed: { name: string }
-  if (NamedError.hasName(input, "MCPFailed")) {
-    const data = isRecord(input) && isRecord(input.data) ? stringField(input.data, "name") : undefined
-    return `MCP server "${data}" failed. Note, opencode does not support MCP authentication yet.`
-  }
+// AccountServiceError, AccountTransportError: TaggedErrorClass
+function formatAccountError(input: unknown): string | undefined {
+  if (!isTaggedError(input, "AccountServiceError") && !isTaggedError(input, "AccountTransportError")) return undefined
+  return stringField(input, "message") ?? ""
+}
 
-  // AccountServiceError, AccountTransportError: TaggedErrorClass
-  if (isTaggedError(input, "AccountServiceError") || isTaggedError(input, "AccountTransportError")) {
-    return stringField(input, "message") ?? ""
-  }
+// ProviderModelNotFoundError: { providerID: string, modelID: string, suggestions?: string[] }
+function formatProviderModelNotFound(input: unknown): string | undefined {
+  const data = configData(input, "ProviderModelNotFoundError")
+  if (!data) return undefined
+  const suggestions = Array.isArray(data.suggestions) ? data.suggestions.filter((x) => typeof x === "string") : []
+  return [
+    `Model not found: ${stringField(data, "providerID")}/${stringField(data, "modelID")}`,
+    ...(suggestions.length ? ["Did you mean: " + suggestions.join(", ")] : []),
+    `Try: \`opencode models\` to list available models`,
+    `Or check your config (opencode.json) provider/model names`,
+  ].join("\n")
+}
 
-  // ProviderModelNotFoundError: { providerID: string, modelID: string, suggestions?: string[] }
-  const providerModelNotFound = configData(input, "ProviderModelNotFoundError")
-  if (providerModelNotFound) {
-    const suggestions = Array.isArray(providerModelNotFound.suggestions)
-      ? providerModelNotFound.suggestions.filter((x) => typeof x === "string")
-      : []
-    return [
-      `Model not found: ${stringField(providerModelNotFound, "providerID")}/${stringField(providerModelNotFound, "modelID")}`,
-      ...(suggestions.length ? ["Did you mean: " + suggestions.join(", ")] : []),
-      `Try: \`opencode models\` to list available models`,
-      `Or check your config (opencode.json) provider/model names`,
-    ].join("\n")
-  }
+// ProviderInitError: { providerID: string }
+function formatProviderInit(input: unknown): string | undefined {
+  const data = configData(input, "ProviderInitError")
+  if (!data) return undefined
+  return `Failed to initialize provider "${stringField(data, "providerID")}". Check credentials and configuration.`
+}
 
-  // ProviderInitError: { providerID: string }
-  const providerInit = configData(input, "ProviderInitError")
-  if (providerInit) {
-    return `Failed to initialize provider "${stringField(providerInit, "providerID")}". Check credentials and configuration.`
-  }
+// ConfigJsonError: { path: string, message?: string }
+function formatConfigJson(input: unknown): string | undefined {
+  const data = configData(input, "ConfigJsonError")
+  if (!data) return undefined
+  const message = stringField(data, "message")
+  return `Config file at ${stringField(data, "path")} is not valid JSON(C)` + (message ? `: ${message}` : "")
+}
 
-  // ConfigJsonError: { path: string, message?: string }
-  const configJson = configData(input, "ConfigJsonError")
-  if (configJson) {
-    const message = stringField(configJson, "message")
-    return `Config file at ${stringField(configJson, "path")} is not valid JSON(C)` + (message ? `: ${message}` : "")
-  }
+// ConfigDirectoryTypoError: { dir: string, path: string, suggestion: string }
+function formatConfigDirectoryTypo(input: unknown): string | undefined {
+  const data = configData(input, "ConfigDirectoryTypoError")
+  if (!data) return undefined
+  return `Directory "${stringField(data, "dir")}" in ${stringField(data, "path")} is not valid. Rename the directory to "${stringField(data, "suggestion")}" or remove it. This is a common typo.`
+}
 
-  // ConfigDirectoryTypoError: { dir: string, path: string, suggestion: string }
-  const configDirectoryTypo = configData(input, "ConfigDirectoryTypoError")
-  if (configDirectoryTypo) {
-    return `Directory "${stringField(configDirectoryTypo, "dir")}" in ${stringField(configDirectoryTypo, "path")} is not valid. Rename the directory to "${stringField(configDirectoryTypo, "suggestion")}" or remove it. This is a common typo.`
-  }
+// ConfigFrontmatterError: { message: string }
+function formatConfigFrontmatter(input: unknown): string | undefined {
+  const data = configData(input, "ConfigFrontmatterError")
+  if (!data) return undefined
+  return stringField(data, "message") ?? ""
+}
 
-  // ConfigFrontmatterError: { message: string }
-  const configFrontmatter = configData(input, "ConfigFrontmatterError")
-  if (configFrontmatter) {
-    return stringField(configFrontmatter, "message") ?? ""
-  }
+// ConfigRemoteAuthError: { url: string, remote: string }
+function formatConfigRemoteAuth(input: unknown): string | undefined {
+  const data = configData(input, "ConfigRemoteAuthError")
+  if (!data) return undefined
+  const url = stringField(data, "url")
+  const remote = stringField(data, "remote")
+  return [
+    `Failed to load remote config${remote ? ` from ${remote}` : ""}: the server returned a login page instead of JSON.`,
+    `Authentication is missing or has expired (the endpoint is likely behind an SSO or identity-aware proxy).`,
+    ...(url ? [`Run \`opencode auth login ${url}\` to re-authenticate.`] : []),
+  ].join("\n")
+}
 
-  // ConfigRemoteAuthError: { url: string, remote: string }
-  const remoteAuth = configData(input, "ConfigRemoteAuthError")
-  if (remoteAuth) {
-    const url = stringField(remoteAuth, "url")
-    const remote = stringField(remoteAuth, "remote")
-    return [
-      `Failed to load remote config${remote ? ` from ${remote}` : ""}: the server returned a login page instead of JSON.`,
-      `Authentication is missing or has expired (the endpoint is likely behind an SSO or identity-aware proxy).`,
-      ...(url ? [`Run \`opencode auth login ${url}\` to re-authenticate.`] : []),
-    ].join("\n")
-  }
+// ConfigInvalidError: { path?: string, message?: string, issues?: Array<{ message: string, path: string[] }> }
+function formatConfigInvalid(input: unknown): string | undefined {
+  const data = configData(input, "ConfigInvalidError")
+  if (!data) return undefined
+  const path = stringField(data, "path")
+  const message = stringField(data, "message")
+  const issues = configIssues(data)
+  return [
+    `Configuration is invalid${path && path !== "config" ? ` at ${path}` : ""}` + (message ? `: ${message}` : ""),
+    ...issues.map((issue) => "↳ " + issue.message + " " + issue.path.join(".")),
+  ].join("\n")
+}
 
-  // ConfigInvalidError: { path?: string, message?: string, issues?: Array<{ message: string, path: string[] }> }
-  const configInvalid = configData(input, "ConfigInvalidError")
-  if (configInvalid) {
-    const path = stringField(configInvalid, "path")
-    const message = stringField(configInvalid, "message")
-    const issues = configIssues(configInvalid)
-    return [
-      `Configuration is invalid${path && path !== "config" ? ` at ${path}` : ""}` + (message ? `: ${message}` : ""),
-      ...issues.map((issue) => "↳ " + issue.message + " " + issue.path.join(".")),
-    ].join("\n")
+// UICancelledError: user cancelled an interactive CLI prompt
+function formatUICancelled(input: unknown): string | undefined {
+  if (!isTaggedError(input, "UICancelledError") && !NamedError.hasName(input, "UICancelledError")) return undefined
+  return ""
+}
+
+// Order matters: the first formatter that recognizes the input wins.
+const FORMATTERS: ErrorFormatter[] = [
+  formatCliError,
+  formatMcpFailed,
+  formatAccountError,
+  formatProviderModelNotFound,
+  formatProviderInit,
+  formatConfigJson,
+  formatConfigDirectoryTypo,
+  formatConfigFrontmatter,
+  formatConfigRemoteAuth,
+  formatConfigInvalid,
+  formatUICancelled,
+]
+
+export function FormatError(input: unknown): string | undefined {
+  if (input instanceof Error && isRecord(input.cause) && "body" in input.cause) {
+    const formatted = FormatError(input.cause.body)
+    if (formatted) return formatted
   }
 
-  // UICancelledError: user cancelled an interactive CLI prompt
-  if (isTaggedError(input, "UICancelledError") || NamedError.hasName(input, "UICancelledError")) {
-    return ""
+  for (const format of FORMATTERS) {
+    const result = format(input)
+    if (result !== undefined) return result
   }
+
   return undefined
 }
 
 export function FormatUnknownError(input: unknown): string {
   return errorFormat(input)
-}
+}
\ No newline at end of file
diff --git a/packages/opencode/test/cli/error.test.ts b/packages/opencode/test/cli/error.test.ts
index b29ca2b3..127cb4dd 100644
--- a/packages/opencode/test/cli/error.test.ts
+++ b/packages/opencode/test/cli/error.test.ts
@@ -92,4 +92,61 @@ describe("cli.error", () => {
   test("formats cancelled UI errors as empty output", () => {
     expect(FormatError(new UI.CancelledError())).toBe("")
   })
-})
+
+  test("formats CLI errors and applies their exit code", () => {
+    const previous = process.exitCode
+    try {
+      expect(FormatError({ _tag: "CliError", message: "something broke", exitCode: 3 })).toBe("something broke")
+      expect(process.exitCode).toBe(3)
+    } finally {
+      process.exitCode = previous ?? 0
+    }
+    expect(process.exitCode).toBe(previous ?? 0)
+  })
+
+  test("formats CLI errors without a message as empty output", () => {
+    const previous = process.exitCode
+    try {
+      expect(FormatError({ _tag: "CliError" })).toBe("")
+    } finally {
+      process.exitCode = previous ?? 0
+    }
+  })
+
+  test("formats remote config auth errors with a login hint", () => {
+    const data = { url: "https://config.example.com", remote: "team-config" }
+    const expected = [
+      "Failed to load remote config from team-config: the server returned a login page instead of JSON.",
+      "Authentication is missing or has expired (the endpoint is likely behind an SSO or identity-aware proxy).",
+      "Run `opencode auth login https://config.example.com` to re-authenticate.",
+    ].join("\n")
+
+    expect(FormatError({ name: "ConfigRemoteAuthError", data })).toBe(expected)
+    expect(FormatError({ _tag: "ConfigRemoteAuthError", ...data })).toBe(expected)
+  })
+
+  test("formats remote config auth errors without a url", () => {
+    const expected = [
+      "Failed to load remote config: the server returned a login page instead of JSON.",
+      "Authentication is missing or has expired (the endpoint is likely behind an SSO or identity-aware proxy).",
+    ].join("\n")
+
+    expect(FormatError({ _tag: "ConfigRemoteAuthError" })).toBe(expected)
+  })
+
+  test("formats config invalid errors with no path and no issues", () => {
+    expect(FormatError({ _tag: "ConfigInvalidError", path: "config" })).toBe("Configuration is invalid")
+  })
+
+  test("unwraps errors nested under cause.body", () => {
+    const wrapped = new Error("outer", { cause: { body: { _tag: "ProviderInitError", providerID: "anthropic" } } })
+
+    expect(FormatError(wrapped)).toBe('Failed to initialize provider "anthropic". Check credentials and configuration.')
+  })
+
+  test("returns undefined for errors it does not recognize", () => {
+    expect(FormatError({ _tag: "SomethingElse", message: "nope" })).toBeUndefined()
+    expect(FormatError("just a string")).toBeUndefined()
+    expect(FormatError(undefined)).toBeUndefined()
+  })
+})
\ No newline at end of file