Error recovery cheat-sheet

Condensed pairings of common LazyBridge errors and the canonical fix. All errors follow the four-part body documented in codegen-contract.md: what failed, what was passed, what's expected, and a concrete fix snippet at the bottom. This page gathers the most common shapes for quick LLM lookup.

Error / Pattern	Cause	Fix
PlanCompileError: Step 'X' (#n) — context=from_step('typo') references unknown step	Sentinel points at a step that doesn't exist (typo, forward-ref, or auto-named _anon_* step)	Replace with the suggested name from the error's "Did you mean 'Y'?" hint, or pass a real name= to the referent step
PlanCompileError: same parallel band	from_step("sibling") inside a parallel band — siblings can't see each other's output	Either move the reader after the band, or use from_parallel_all("first_in_band") to aggregate
PlanCompileError: from_agent('X') — missing 'store='	The source agent has no store= so its output can't be persisted for cross-step read	Pass store=Store(...) to the source Agent, or use from_step('step_name') instead
ValueError: MCP.stdio('X') requires an explicit allow=[...] or deny=[...]	0.7.9 deny-by-default for MCP servers	Pass allow=["*"] after auditing, or restrict with a glob allow=["fs.read_*"]
ValueError: Agent(name=...) is required when engine is not LLMEngine	T7 — non-LLM engines (Plan/Supervisor/Human) can't auto-name from a model string	Add name="my_agent" to the Agent constructor
ValueError: Agent(model=..., engine=...) — can't pass both	T6 — model= is shorthand for LLMEngine(model); engine= is the explicit form	Pick one — drop model= if you want a custom engine
Tool.__init__: mode='auto' was removed in 0.7.9	0.7.9 deleted the graceful-fallback ladder	Pass mode="signature" (introspect, default), mode="llm" (let an LLM build the schema), or mode="hybrid"
AttributeError: type object 'Agent' has no attribute 'from_chain'	0.7.9 deleted Agent.from_chain / from_engine / from_model / from_plan / from_parallel	Use Agent.chain(a, b) / Agent.parallel(...) or Agent(engine=...) for the others
ValueError: LLMEngine(tool_choice='parallel') was removed in 0.7.9	0.7.9 deleted this knob — concurrent tools are the default and can't be disabled	Drop the argument (or use tool_choice='auto' / 'any')
UnsupportedNativeToolError: provider X does not support CODE_EXECUTION	The provider's supported_native_tools doesn't cover the requested tool	Either swap to a provider that does (see lazybridge.matrix.provider_capabilities()), or pass strict_native_tools=False to let the tool be silently dropped
UnsupportedFeatureError: provider X with structured_output + tools	DeepSeek-legacy / OpenAI-image limits — provider can't combine both	Either drop output_type= for the tool-using turn, or drop the conflicting tool
ValueError: EncryptedStoreAdapter: stored value is not an lb-enc-v1 token	Adapter pointed at a plaintext Store (mixed-mode reads are unsafe)	Either decrypt+re-encrypt the legacy rows, or unwrap the adapter to read them
StreamStallError: no token in 90s	Provider stream went silent past stream_idle_timeout	Lower the timeout, or wrap the call in retry logic, or switch to non-streaming
ToolTimeoutError: tool X exceeded 30s	Tool wall-clock exceeded tool_timeout	Raise the timeout on the LLMEngine, or make the tool faster
RuntimeError: async def functions are not natively supported	pytest-asyncio not installed in the test env	pip install -e '.[test]' (see CONTRIBUTING.md)
ModuleNotFoundError: lazybridge.external_tools.report_builder	Reporting moved to selvaz/LazyReport in 0.7.9	pip install lazybridge-reports, then import lazybridge_reports
ImportError: EncryptedStoreAdapter requires 'cryptography'	Opt-in extra not installed	pip install 'lazybridge[encryption]'
PackageNotFoundError: lazybridge reads as version 0.7.0	Stale dev install + new source tree	pip install -e . to refresh the editable install's metadata

When the error doesn't appear in the table

1. Read the bottom of the error message verbatim — the four-part body ends with a literal fix snippet, often the exact replacement line of code.
2. Cross-reference the symbol against lazybridge/llms.json — the avoid list and renames map cover every 0.7.9 deletion.
3. If the symbol is from a 0.4-era import path (LazyAgent/LazyTool/LazySession/LazyContext), see the migration guide.