fix(hook-message-injector): add process-unique prefix to message/part IDs to prevent storage collisions

IDs now include a random 8-hex-char prefix per process (e.g. msg_a1b2c3d4_000001)
preventing collisions when counters reset across process restarts.

src/features/hook-message-injector/injector.test.ts

@@ -197,7 +197,7 @@ describe("findFirstMessageWithAgentFromSDK", () => {
 describe("generateMessageId", () => {
   it("returns deterministic sequential IDs with fixed format", () => {
     // given
-    const format = /^msg_\d{12}$/
+    const format = /^msg_[0-9a-f]{8}_\d{6}$/
 
     // when
     const firstId = generateMessageId()
@@ -206,14 +206,15 @@ describe("generateMessageId", () => {
     // then
     expect(firstId).toMatch(format)
     expect(secondId).toMatch(format)
-    expect(Number(secondId.slice(4))).toBe(Number(firstId.slice(4)) + 1)
+    expect(secondId.split("_")[1]).toBe(firstId.split("_")[1])
+    expect(Number(secondId.split("_")[2])).toBe(Number(firstId.split("_")[2]) + 1)
   })
 })
 
 describe("generatePartId", () => {
   it("returns deterministic sequential IDs with fixed format", () => {
     // given
-    const format = /^prt_\d{12}$/
+    const format = /^prt_[0-9a-f]{8}_\d{6}$/
 
     // when
     const firstId = generatePartId()
@@ -222,7 +223,8 @@ describe("generatePartId", () => {
     // then
     expect(firstId).toMatch(format)
     expect(secondId).toMatch(format)
-    expect(Number(secondId.slice(4))).toBe(Number(firstId.slice(4)) + 1)
+    expect(secondId.split("_")[1]).toBe(firstId.split("_")[1])
+    expect(Number(secondId.split("_")[2])).toBe(Number(firstId.split("_")[2]) + 1)
   })
 })
 

src/features/hook-message-injector/injector.ts

@@ -1,4 +1,5 @@
 import { existsSync, mkdirSync, readFileSync, readdirSync, writeFileSync } from "node:fs"
+import { randomBytes } from "node:crypto"
 import { join } from "node:path"
 import type { PluginInput } from "@opencode-ai/plugin"
 import { MESSAGE_STORAGE, PART_STORAGE } from "./constants"
@@ -29,6 +30,7 @@ interface SDKMessage {
   }
 }
 
+const processPrefix = randomBytes(4).toString("hex")
 let messageCounter = 0
 let partCounter = 0
 
@@ -208,11 +210,11 @@ export function findFirstMessageWithAgent(messageDir: string): string | null {
 }
 
 export function generateMessageId(): string {
-  return `msg_${String(++messageCounter).padStart(12, "0")}`
+  return `msg_${processPrefix}_${String(++messageCounter).padStart(6, "0")}`
 }
 
 export function generatePartId(): string {
-  return `prt_${String(++partCounter).padStart(12, "0")}`
+  return `prt_${processPrefix}_${String(++partCounter).padStart(6, "0")}`
 }
 
 function getOrCreateMessageDir(sessionID: string): string {