fix(tool-execute-before): resolve subagent_type for TUI display

OpenCode TUI reads input.subagent_type to display task type. When
subagent_type was missing (e.g., category-only or session continuation),
TUI showed 'Unknown Task'.

Fix:
- category provided: always set subagent_type to 'sisyphus-junior'
  (previously only when subagent_type was absent)
- session_id continuation: resolve agent from session's first message
- fallback to 'continue' if session has no agent info

src/plugin/tool-execute-before.ts

@@ -3,6 +3,7 @@ import type { PluginContext } from "./types"
 import { getMainSessionID } from "../features/claude-code-session-state"
 import { clearBoulderState } from "../features/boulder-state"
 import { log } from "../shared"
+import { resolveSessionAgent } from "./session-agent-resolver"
 
 import type { CreatedHooks } from "../create-hooks"
 
@@ -34,8 +35,13 @@ export function createToolExecuteBeforeHandler(args: {
       const argsObject = output.args
       const category = typeof argsObject.category === "string" ? argsObject.category : undefined
       const subagentType = typeof argsObject.subagent_type === "string" ? argsObject.subagent_type : undefined
-      if (category && !subagentType) {
+      const sessionId = typeof argsObject.session_id === "string" ? argsObject.session_id : undefined
+
+      if (category) {
         argsObject.subagent_type = "sisyphus-junior"
+      } else if (!subagentType && sessionId) {
+        const resolvedAgent = await resolveSessionAgent(ctx.client, sessionId)
+        argsObject.subagent_type = resolvedAgent ?? "continue"
       }
     }