A delegated child's execute_code kernel was keyed correctly
(<owner>:🧒:<session>) but counted against the process-wide
max_session_kernels LRU cap (default 4) like any other kernel. In a fan-out
wider than the cap every child's first cell spawned a kernel and evicted the
oldest sibling's, so the sibling's next cell started a fresh interpreter and
NameError'd on state its own previous cell had set — while the tool schema
promised "variables, imports, and loaded data survive across execute_code
calls". Finished children's kernels also squatted the cap for
kernel_idle_timeout (1800 s) after the child was gone. 48 NameErrors across 28
subagent lanes in the Sep 10-14 retrospective.
A live child's kernel (local and remote) is now pinned: exempt from LRU
eviction while the child runs, disposed by the delegation cleanup path
(shutdown_kernels_for_delegated_child) as soon as the child finishes. Top-level
sessions keep the existing cap and idle reaping unchanged.
_callback_api() now yields (getter, setter) pairs for every per-thread prompt
(approval, sudo, vault unlock); the kernel cell captured and restored the old
fixed 4-tuple. Iterate the table so a cell carries every callback and a future
addition needs no change here. Test recorder unpacks the new shape.
Also: perfectionist import order in ui-tui interfaces.ts (CI lint).
For each issue anchor present in BASE 63279301bc non-test .py and absent on HEAD, the BASE comment/docstring block was re-attached at the HEAD location of the code it explained (matched by the distinctive code line / enclosing def). Sentences already covered by an existing HEAD comment were deduped; the issue number always survives. Insert-only: no code lines changed.
Widens the Windows parent-death fix to the class: the kernel inherits
the read end of a pipe whose only write end lives in the host, so host
death by any means (SIGKILL, OOM, crash) is EOF and the kernel exits.
Stdin EOF alone only reaches the runner between cells, so a kernel
SIGKILLed mid-cell used to outlive its host indefinitely. The
integration test now runs on every platform and is trimmed to the
contract (kill host mid-cell, kernel gone), not the handle plumbing.
Session kernels: a kernel mid-spawn (proc=None) read as dead, so every
concurrent cell for one owner replaced the registry entry and the
winner's process leaked outside the registry (110 live kernels, 1.1 GB,
330 threads under one 4-capped process). Reap/evict also tore down
kernels with cells attached, rmtree-ing the staging dir under the
spawner. Kernels now track attached cells: only settled kernels are
reaped/evicted, a kernel dropped while busy is torn down by its last
cell, and in-cell registry pops never remove a replacement.
LSP: a directory holding __init__.py is a package, not a project root.
hermes_cli/setup.py matched the python marker list and gave every
worktree a second pyright rooted at hermes_cli/ (70 of 105 reaped
clients in one session, ~40 servers / 8.7 GB live).
* 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)
---------
Co-authored-by: Teknium <127238744+teknium1@users.noreply.github.com>
