fix: _is_unattended_context requires positive cron/subagent signal (#1554)

[Lexus2016]

Summary

Fixes the CI failures on PR #1550 (accepted issue #1542 — suppress pending_approval retries, 44% of terminal failures).

Problem

PR #1550 introduced _is_unattended_context() to convert pending_approval into non-retryable blocked in cron/subagent contexts. But the implementation defaulted to True whenever no interactive CLI, gateway, or cron session was detected — a catch-all "nobody's home" default. In the non-interactive CI test environment, this evaluates to True, breaking every test that expects pending_approval behavior (slices 2/8 and 8/8).

Fix (#1554)

_is_unattended_context() now requires a positive signal of an unattended context:

1. HERMES_CRON_SESSION env var (already set in cron/scheduler.py), OR
2. A subagent contextvar (_hermes_subagent_ctx), set in delegate_tool._run_single_child

Why a contextvar instead of HERMES_SUBAGENT?

Issue #1554 proposed checking a HERMES_SUBAGENT env var, but that env var does not exist on main (0 grep matches). Subagents are identified by the _delegate_depth attribute on the agent instance, which module-level tools/approval.py cannot access. The correct mechanism is a contextvars.ContextVar — mirroring the existing _hermes_interactive_ctx pattern (introduced for the same thread-safety reason: concurrent ACP/gateway sessions on a shared ThreadPoolExecutor). The contextvar is set in _run_single_child (the single entry point for both single and batch delegation) and reset in its finally block.

Validation

• All 11 test_approval_cron_block.py tests pass (6 existing + 5 new)
• 392 approval/delegation tests pass
• 338 subagent/delegation tests pass
• ruff check + format clean
• The 3 test_approval.py failures (tee/sensitive-redirect patterns) are pre-existing — confirmed by running them against the pre-fix commit c25748edf; they fail identically and are caused by running as root (~/.bashrc path resolution)

Size note

236 insertions across 3 files — over the 200-line autonomous-merge cap. The three files are tightly coupled (contextvar declared in approval.py, set in delegate_tool.py, tested in the test file); no smaller coherent slice exists. Holding for human review.

Closes #1554

Co-Authored-By: Hermes Evolution evolution@hermes.ai

[Lexus2016]

Code-review (evolution-integration, 2026-08-01): PASSED review but BLOCKED by autonomous merge gate for two policy reasons (both require human merge):

1. HIGH_RISK_PATH: touches tools/approval.py (core approval-gating machinery).
2. DIFF_TOO_LARGE: 236 changed lines > 200-line self-merge cap.

Verification performed: (a) Not dead code — _is_unattended_context() has 2 real call sites (check_all_command_guards, check_execute_code_guard); set_hermes_subagent_context() is called from delegate_tool._run_single_child with proper reset in finally. (b) No category error — requires a positive signal (HERMES_CRON_SESSION or the new _hermes_subagent_ctx contextvar), fixing exactly the #1554 misfire; the contextvar mirrors the existing _hermes_interactive_ctx pattern. (c) Independently confirmed HERMES_SUBAGENT does NOT exist on origin/main (the competing #1555 relied on it → dead code, closed). (d) CI fully green (8 slices + e2e). Ready for human squash-merge.