Sample
Observe the implicit parent greenlet control return behavior when a switched-to greenlet completes
sha256:bdf2e2f5b210f6ce304b4c4a450f53972eceeab15ddf990f5cea4c215abe7355
PUBLISHED
L3_CONTRACT_PASS
MIT-0
Execution evidence
Declared environment and signed verification runs are separated so you can see exactly what this sample proves.
Evidence basisSigned contract pass
Verification receipts1
Verification levelL3_CONTRACT_PASS
Declared environment
- Execution context
- python
- Operating system
- linux
- Architecture
- x64
- Runtime
- python
- Language
- python
- Package manager
- pip
Verification-run environments
- Execution context
- python 3.12
- Operating system
- linux alpine · musl
- Architecture
- x64
- Runtime
- python 3.12
- Language
- python
- Package manager
- pip
- Execution
- container · docker
CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · python@1 · 2026-08-17
Case
- Goal
- Observe the implicit parent greenlet control return behavior when a switched-to greenlet completes HOW
- Packages
-
greenlet 3.0.3
- Environment
- python
- Created
- 2026-08-17T17:46:23Z
Commonly assumed
Control implicitly returns to the greenlet that called switch(), behaving like a symmetric coroutine yield or regular function call
The sample's author recorded this as what a developer or model would expect here. The contract below is what actually ran.
Contract
- When greenlet B switches to greenlet C, and C finishes its execution, control returns to C's parent (its creator), rather than back to B that performed the switch
- f1 starts and switches to f2 using g2.switch()
- f2 completes and control implicitly returns to main, not f1, leaving f1 suspended forever
- result contains 'main end' but never receives 'f1 end'
Files
- NOTES.md
- csx.json
- requirements.txt
- test_contract.py
Download the source artifact (tar.gz)
Origin Seeder
csx-seed
Verification receipts
- python 3.12 · linux alpine/x64 · docker · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · python@1 · 2026-08-17 · ed25519:d91480838ac982c9