refactor: unify system directive prefix for keyword-detector filtering

- Add shared/system-directive.ts with SYSTEM_DIRECTIVE_PREFIX constant
- Unify all system message prefixes to [SYSTEM DIRECTIVE: OH-MY-OPENCODE - ...]
- Add isSystemDirective() filter to keyword-detector to skip system messages
- Update prometheus-md-only tests to use new prefix constants

src/hooks/prometheus-md-only/constants.ts

@@ -1,3 +1,5 @@
+import { createSystemDirective, SystemDirectiveTypes } from "../../shared/system-directive"
+
 export const HOOK_NAME = "prometheus-md-only"
 
 export const PROMETHEUS_AGENTS = ["Prometheus (Planner)"]
@@ -12,7 +14,7 @@ export const PLANNING_CONSULT_WARNING = `
 
 ---
 
-[SYSTEM DIRECTIVE - READ-ONLY PLANNING CONSULTATION]
+${createSystemDirective(SystemDirectiveTypes.PROMETHEUS_READ_ONLY)}
 
 You are being invoked by Prometheus (Planner), a READ-ONLY planning agent.
 

src/hooks/prometheus-md-only/index.test.ts

@@ -3,6 +3,7 @@ import { mkdirSync, rmSync, writeFileSync } from "node:fs"
 import { join } from "node:path"
 import { createPrometheusMdOnlyHook } from "./index"
 import { MESSAGE_STORAGE } from "../../features/hook-message-injector"
+import { SYSTEM_DIRECTIVE_PREFIX, createSystemDirective, SystemDirectiveTypes } from "../../shared/system-directive"
 
 describe("prometheus-md-only", () => {
   const TEST_SESSION_ID = "test-session-prometheus"
@@ -167,7 +168,7 @@ describe("prometheus-md-only", () => {
       await hook["tool.execute.before"](input, output)
 
       // #then
-      expect(output.args.prompt).toContain("[SYSTEM DIRECTIVE - READ-ONLY PLANNING CONSULTATION]")
+      expect(output.args.prompt).toContain(SYSTEM_DIRECTIVE_PREFIX)
       expect(output.args.prompt).toContain("DO NOT modify any files")
     })
 
@@ -187,7 +188,7 @@ describe("prometheus-md-only", () => {
       await hook["tool.execute.before"](input, output)
 
       // #then
-      expect(output.args.prompt).toContain("[SYSTEM DIRECTIVE - READ-ONLY PLANNING CONSULTATION]")
+      expect(output.args.prompt).toContain(SYSTEM_DIRECTIVE_PREFIX)
     })
 
     test("should inject read-only warning when Prometheus calls call_omo_agent", async () => {
@@ -206,7 +207,7 @@ describe("prometheus-md-only", () => {
       await hook["tool.execute.before"](input, output)
 
       // #then
-      expect(output.args.prompt).toContain("[SYSTEM DIRECTIVE - READ-ONLY PLANNING CONSULTATION]")
+      expect(output.args.prompt).toContain(SYSTEM_DIRECTIVE_PREFIX)
     })
 
     test("should not double-inject warning if already present", async () => {
@@ -217,7 +218,7 @@ describe("prometheus-md-only", () => {
         sessionID: TEST_SESSION_ID,
         callID: "call-1",
       }
-      const promptWithWarning = "Some prompt [SYSTEM DIRECTIVE - READ-ONLY PLANNING CONSULTATION] already here"
+      const promptWithWarning = `Some prompt ${SYSTEM_DIRECTIVE_PREFIX} already here`
       const output = {
         args: { prompt: promptWithWarning },
       }
@@ -226,7 +227,7 @@ describe("prometheus-md-only", () => {
       await hook["tool.execute.before"](input, output)
 
       // #then
-      const occurrences = (output.args.prompt as string).split("[SYSTEM DIRECTIVE - READ-ONLY PLANNING CONSULTATION]").length - 1
+      const occurrences = (output.args.prompt as string).split(SYSTEM_DIRECTIVE_PREFIX).length - 1
       expect(occurrences).toBe(1)
     })
   })
@@ -272,7 +273,7 @@ describe("prometheus-md-only", () => {
 
       // #then
       expect(output.args.prompt).toBe(originalPrompt)
-      expect(output.args.prompt).not.toContain("[SYSTEM DIRECTIVE - READ-ONLY PLANNING CONSULTATION]")
+      expect(output.args.prompt).not.toContain(SYSTEM_DIRECTIVE_PREFIX)
     })
   })
 

src/hooks/prometheus-md-only/index.ts

@@ -5,6 +5,7 @@ import { HOOK_NAME, PROMETHEUS_AGENTS, ALLOWED_EXTENSIONS, ALLOWED_PATH_PREFIX,
 import { findNearestMessageWithFields, findFirstMessageWithAgent, MESSAGE_STORAGE } from "../../features/hook-message-injector"
 import { getSessionAgent } from "../../features/claude-code-session-state"
 import { log } from "../../shared/logger"
+import { SYSTEM_DIRECTIVE_PREFIX } from "../../shared/system-directive"
 
 export * from "./constants"
 
@@ -89,7 +90,7 @@ export function createPrometheusMdOnlyHook(ctx: PluginInput) {
       // Inject read-only warning for task tools called by Prometheus
       if (TASK_TOOLS.includes(toolName)) {
         const prompt = output.args.prompt as string | undefined
-        if (prompt && !prompt.includes("[SYSTEM DIRECTIVE - READ-ONLY PLANNING CONSULTATION]")) {
+        if (prompt && !prompt.includes(SYSTEM_DIRECTIVE_PREFIX)) {
           output.args.prompt = prompt + PLANNING_CONSULT_WARNING
           log(`[${HOOK_NAME}] Injected read-only planning warning to ${toolName}`, {
             sessionID: input.sessionID,