refactor(opencode): improve startup time by 38% (#30453)

Co-authored-by: starptech <starptech@starptechs-MBP.fritz.box>

packages/opencode/src/cli/cmd/github.shared.ts

@@ -0,0 +1,30 @@
+import type { SessionLegacy } from "@opencode-ai/core/session/legacy"
+
+export { parseGitHubRemote } from "@/util/repository"
+
+/**
+ * Extracts displayable text from assistant response parts.
+ * Returns null for non-text responses (signals summary needed).
+ * Throws only for truly empty responses.
+ */
+export function extractResponseText(parts: SessionLegacy.Part[]): string | null {
+  const textPart = parts.findLast((p) => p.type === "text")
+  if (textPart) return textPart.text
+
+  // Non-text parts (tools, reasoning, step-start/step-finish, etc.) - signal summary needed
+  if (parts.length > 0) return null
+
+  throw new Error("Failed to parse response: no parts returned")
+}
+
+/**
+ * Formats a PROMPT_TOO_LARGE error message with details about files in the prompt.
+ * Content is base64 encoded, so we calculate original size by multiplying by 0.75.
+ */
+export function formatPromptTooLargeError(files: { filename: string; content: string }[]): string {
+  const fileDetails =
+    files.length > 0
+      ? `\n\nFiles in prompt:\n${files.map((f) => `  - ${f.filename} (${((f.content.length * 0.75) / 1024).toFixed(0)} KB)`).join("\n")}`
+      : ""
+  return `PROMPT_TOO_LARGE: The prompt exceeds the model's context limit.${fileDetails}`
+}