* feat(tools): session-persistent kernels for execute_code (kernel_mode: session)
execute_code spawns a fresh Python process per call, so every multi-step
data task re-loads its inputs: a CSV parsed in call one is gone by call
two, and scripts route state through temp files to survive. Hermes
already rewards programmatic tool calling (execute_code-only turns
refund the iteration budget), which makes the missing half — state that
survives between calls — the bottleneck.
Add opt-in `code_execution.kernel_mode: session`: one persistent kernel
per (task, mode, interpreter, cwd, tool-set). Variables, imports, and
loaded data persist across calls; `reset=true` discards state on demand.
The default `per-call` keeps today's behavior byte-for-byte.
Safety posture is unchanged by design: the child env comes from the same
builder as the per-call path (extracted, not duplicated, so the secret
scrubbing / PYTHONPATH hygiene cannot drift), the RPC server is the same
`_rpc_server_loop` with the same token and a per-cell tool budget, and
output passes the same ANSI strip + secret redaction. A timed-out or
interrupted cell kills the whole kernel tree and the next call respawns
— a wedged kernel can never hang the agent. The kernel env is frozen at
spawn; the schema and config comment say so.
Wire protocol: NDJSON requests on the kernel's stdin; responses framed
on stdout behind a per-kernel random sentinel, with unframed bytes
(fd-level output from user-spawned subprocesses) attributed to the
serialized current cell. The generated RPC client reconnects once when
HERMES_RPC_PERSISTENT=1, because a kernel legitimately outlives the RPC
server's 300s idle window between cells.
Tested on macOS 15 (Apple Silicon), Python 3.11: 13 new tests in
tests/tools/test_code_kernel.py (persistence, reset, error-keeps-kernel,
timeout-kills-kernel, sys.exit ends kernel, subprocess fd passthrough,
schema surface, mode fallback) plus the existing
test_code_execution.py / test_code_execution_modes.py suites (81 passed).
* fix(tools): session kernels get a stable owner, bounded lifetime, and per-cell RPC authority
Addresses the blocking review on the session-kernel design: two
authority/lifecycle boundaries were wrong.
1. Ownership and bounded lifetime. The kernel key's first component is
now the conversation's approval session key (_resolve_owner), not the
per-turn task id run_agent mints per top-level invocation — so state
genuinely survives across user turns of one conversation, and delegated
subagent sessions isolate naturally under their own keys (the task id
remains only the last-resort owner for embeds/tests with no session
context). Lifetime is bounded on four edges: kernels are disposed at the
same session boundary that clears the owner's approval/yolo state
(tools.approval.clear_session -> shutdown_kernels_for_owner), reaped
after code_execution.kernel_idle_timeout seconds idle (default 1800,
swept on every entry), capped process-wide at
code_execution.max_session_kernels live children (default 4, LRU
evicted), and still torn down by reset/death/atexit as before. The
ownership + disposal + idle-reap + cap shape deliberately carries
forward the lifecycle invariants of the earlier session-persistent
implementation in #88637 by @z80dev.
2. Per-cell RPC authority. The serving thread no longer freezes the
spawning cell's context/callbacks for the kernel's life. Each cell
installs a CellAuthority — captured on the calling thread exactly as
propagate_context_to_thread would for a per-call RPC thread — before its
request is written, and retires it on every settle path; _rpc_server_loop
gains a dispatch hook the kernel uses to route each tool call through
the CURRENT cell's context, callbacks, and task id. A call arriving with
no active cell is refused. Interpreter state persists; RPC authority
does not.
Composition with the per-script static guard (see the config note): a
persistent namespace lets cell N+1 invoke objects cell N created, which
a single-cell static scan cannot see — the runtime RPC boundary
(allow-list by name, per-cell budget, per-cell authority) is the
operative cross-cell enforcement in this mode, and the adversarial
alias test pins exactly that.
Tests (9 new): state survives across turns of one conversation;
sessions isolate; clear_session disposes the owner's kernels (and the
next turn starts fresh); the live-kernel cap LRU-evicts with evicted
children proven dead; idle kernels are reaped; a later cell's RPC runs
under that cell's approval callback; a cross-cell alias dispatches under
the CURRENT cell's authority; a settled cell's authority refuses
dispatch; each cell installs a fresh authority. 22/22 kernel tests, 81
code-execution tests, ruff clean. The 7 test-order failures in the
tools/-k-approval selection reproduce identically on the clean branch
base (pre-existing pollution, not this change).
* fix(code-kernel): delegated children get their own kernels — child contexts inherit the parent approval key, so qualify the owner with the delegation session id (live-verified leak, both directions)
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Co-authored-by: Teknium <127238744+teknium1@users.noreply.github.com>
