{"record":{"id":"7ed6fa25939ceffc","repo":"rohitg00/ai-engineering-from-scratch","slug":"illegal-transition-self-state-value-target-v","errorCode":null,"errorMessage":"illegal transition {self.state.value} -> {target.value}","messagePattern":"illegal transition (.+?) -> (.+?)","errorType":"exception","errorClass":"RuntimeError","httpStatus":null,"severity":"error","filePath":"phases/19-capstone-projects/20-agent-harness-loop-contract/code/main.py","lineNumber":195,"sourceCode":"    def plan(self) -> list[Step]:\n        return list(self._plan)\n\n    def _emit(self, etype: str, payload: dict) -> None:\n        if etype not in EVENT_TYPES:\n            raise ValueError(f\"unknown event type: {etype}\")\n        self._events.append(Event(type=etype, payload=payload, ts=time.time()))\n\n    def _transition(self, target: State) -> None:\n        legal: dict[State, set[State]] = {\n            State.IDLE: {State.PLANNING},\n            State.PLANNING: {State.EXECUTING, State.IDLE, State.DONE},\n            State.EXECUTING: {State.AWAITING_TOOL, State.REFLECTING, State.IDLE},\n            State.AWAITING_TOOL: {State.REFLECTING, State.IDLE},\n            State.REFLECTING: {State.PLANNING, State.EXECUTING, State.DONE, State.IDLE},\n            State.DONE: set(),\n        }\n        if target not in legal[self.state]:\n            raise RuntimeError(f\"illegal transition {self.state.value} -> {target.value}\")\n        self.state = target\n\n    def _check_budget(self) -> PullRequest | None:\n        which = self.budget.exceeded()\n        if which is None:\n            return None\n        self._emit(\"budget.warn\", {\"limit\": which})\n        self.hooks.fire(\"on_budget_exceeded\", {\"limit\": which, \"budget\": self.budget})\n        self._reason = f\"budget_exceeded:{which}\"\n        self._prev_state = self.state\n        return self._pause(self._reason)\n\n    def _pause(self, reason: str) -> PullRequest:\n        self._emit(\"session.pause\", {\"reason\": reason})\n        self.hooks.fire(\"on_pause\", {\"reason\": reason})\n        self._transition(State.IDLE)\n        return PullRequest(reason=reason, state=self.state, payload={\"reason\": reason})\n","sourceCodeStart":177,"sourceCodeEnd":213,"githubUrl":"https://github.com/rohitg00/ai-engineering-from-scratch/blob/39ea8a1c6d0b61f071226eff7ede4d4105fed820/phases/19-capstone-projects/20-agent-harness-loop-contract/code/main.py#L177-L213","documentation":"Error \"illegal transition {self.state.value} -> {target.value}\" thrown in rohitg00/ai-engineering-from-scratch.","triggerScenarios":"Thrown at phases/19-capstone-projects/20-agent-harness-loop-contract/code/main.py:195 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":[],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"39ea8a1c6d0b61f071226eff7ede4d4105fed820","analyzedAt":"2026-08-26T03:13:46.626Z","schemaVersion":2},"datasetVersion":"2026-08-26T07:17:17.940Z"}