fix(delegation): preserve parent session identity across child runs - #75856
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…cess env AIAgent.__init__ calls set_current_session_id(self.session_id), which mutated both the task-local ContextVar and the process-global os.environ. Because _build_child_agent wraps construction in delegated_child_context(), the ContextVar write is harmless (task-local), but the os.environ write clobbered the parent's HERMES_SESSION_ID for the rest of the process — leaking the child id into parent tools and subprocesses spawned after the child was built. Root cause of HermesPRDelegationSessionContext: parent 20260729_212118_5d797e dispatched child 20260730_160515_736ea1; later parent terminal inherited HERMES_SESSION_ID=the child. Fix: set_current_session_id() skips the process-global os.environ write when called from within a delegated_child_context(). The child's own tools and subprocesses still resolve their id through the ContextVar (task-local), while the parent's process-wide env keeps the parent's session identity. Root agents (CLI, gateway, cron) retain both paths. Adds 7 regression tests covering single child, concurrent children (8 parallel), parent-tool observation after construction, and root-agent session rotation backward compatibility. All pass; ruff clean.
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૮ >ﻌ< ა ci reviewran on abf34d0 ℹ️ InfoDesktop E2E visual evidence · View test artifacts · View job2 visual diffs. inline evidence upload failed. Failed to upload diff-1508682a2ae8-boot-ready-diff.png with gh image (exit code 1): Error uploading /home/runner/work/_temp/e2e-evidence/diff-1508682a2ae8-boot-ready-diff.png: step 0 (get upload token): uploadToken not found on repo page — do you have write access to NousResearch/hermes-agent? (or, if NousResearch enforces SAML SSO, authorize at https://github.com/orgs/NousResearch/sso) |
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Summary
Delegated child agents no longer clobber the parent's session identity:
set_current_session_id()now suppresses ContextVar/env writes while a delegated-child scope is active, anddelegated_child_context()saves and restores the parent id around the child run.Root cause: child
AIAgent()construction happens on the parent thread, and agent init unconditionally callsset_current_session_id(child.session_id)— which writes both the ContextVar and process-globalHERMES_SESSION_ID. Main's own comment intools/delegate_tool.pydocuments the clobber but only works around it for the async wake-sid; every parent subprocess spawned after a delegation carried the last child's identity.The guard lives at the helper level so single, batch, and nested delegation are all covered; child subprocesses still receive the correct child id via the existing scoped context bridge.
Salvaged from #74858 by @Xipong with authorship preserved (1 commit cherry-picked onto current main).
Changes
gateway/session_context.py: delegation-scope guard inset_current_session_id(); save/restore in the delegated-child scope.tools/delegate_tool.py: use the scoped context at the child construction site.tests/gateway/test_delegation_session_id_leak.py: single/nested/concurrent regression tests using realbuild_subprocess_env.Validation
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