Fix: prevent system-reminder tags from triggering mode keywords (#1155)

Automated system messages with <system-reminder> tags were incorrectly
triggering [search-mode], [analyze-mode], and other keyword modes when
they contained words like "search", "find", "explore", etc.

Changes:
- Add removeSystemReminders() to strip <system-reminder> content before keyword detection
- Add hasSystemReminder() utility function
- Update keyword-detector to clean text before pattern matching
- Add comprehensive test coverage for system-reminder filtering

Fixes issue where automated system notifications caused agents to
incorrectly enter MAXIMUM SEARCH EFFORT mode.

Co-authored-by: TheEpTic <git@eptic.me>

src/hooks/keyword-detector/index.ts

@@ -2,7 +2,7 @@ import type { PluginInput } from "@opencode-ai/plugin"
 import { detectKeywordsWithType, extractPromptText, removeCodeBlocks } from "./detector"
 import { isPlannerAgent } from "./constants"
 import { log } from "../../shared"
-import { isSystemDirective } from "../../shared/system-directive"
+import { hasSystemReminder, isSystemDirective, removeSystemReminders } from "../../shared/system-directive"
 import { getMainSessionID, getSessionAgent, subagentSessions } from "../../features/claude-code-session-state"
 import type { ContextCollector } from "../../features/context-injector"
 
@@ -32,7 +32,10 @@ export function createKeywordDetectorHook(ctx: PluginInput, collector?: ContextC
       }
 
       const currentAgent = getSessionAgent(input.sessionID) ?? input.agent
-      let detectedKeywords = detectKeywordsWithType(removeCodeBlocks(promptText), currentAgent)
+
+      // Remove system-reminder content to prevent automated system messages from triggering mode keywords
+      const cleanText = removeSystemReminders(promptText)
+      let detectedKeywords = detectKeywordsWithType(removeCodeBlocks(cleanText), currentAgent)
 
       if (isPlannerAgent(currentAgent)) {
         detectedKeywords = detectedKeywords.filter((k) => k.type !== "ultrawork")