Hardening fixes for compression, Hindsight, and env snapshots

[ai-ag2026]

Summary

This PR collects small, generic hardening fixes that were carried locally and replay cleanly on current origin/main:

• tolerate non-object tool-call args while compressing context
• surface Hindsight retain timeouts clearly instead of returning ambiguous failures
• scrub secret-looking variables from terminal environment snapshots
• keep shell snapshot temp filenames stable across export -p | grep ... && mv ... pipelines so exported env/session PATH changes persist correctly

Verification

Run locally on the PR branch after the latest push:

PYTHONPATH="$PWD" /home/manfred/.hermes/hermes-agent/venv/bin/python -m pytest \
  tests/agent/test_context_compressor.py \
  tests/plugins/memory/test_hindsight_provider.py \
  tests/tools/test_init_session_cwd_respect.py \
  tests/tools/test_base_environment.py \
  -q
# 301 passed in 10.64s

PYTHONPATH="$PWD" /home/manfred/.hermes/hermes-agent/venv/bin/python -m pytest \
  tests/tools/test_local_shell_init.py \
  -q
# 16 passed in 1.01s

git diff --check origin/main...HEAD
# rc=0

Earlier CI caught the shell-snapshot temp-name regression in tests/tools/test_local_shell_init.py; this branch now includes the fix and the local reproducer suite is green.

[teknium1]

Thanks for the focused hardening work. Two parts still target current-main behavior: plugins/memory/hindsight/__init__.py:274-281 still exposes a raw future timeout, and tools/environments/base.py:502,650 still snapshots all exported variables.

Problems

• The compression hunk is already superseded. Current main commit 3804df5b36aeb2fcb6ae1c2bc38dd53f46c4de01 rejects non-dict parsed arguments at agent/context_compressor.py:638-639; its coverage includes list and scalar arguments at tests/agent/test_summarize_tool_result_type_safety.py:190-195.

Suggested changes

• When salvaging, omit fa859c1b0429 and its duplicate compressor test; preserve the independent Hindsight and shell-snapshot changes.

Automated hermes-sweeper review.

[ai-ag2026]

Summary

Closing this older combined hardening PR after reconciling every slice against the maintained replacements and current main.

Why

• The terminal environment snapshot hardening now lives in fix: harden subprocess env handling (scrub secrets, isolate browser sessions) #59840, including the secret filtering, atomic $BASHPID temp-file flow, private umask assertions, and additional failure-path hardening.
• The Hindsight retain-timeout handling lives in fix(hindsight): surface retain timeouts clearly #59842. Its core commit is patch-identical to this PR's Hindsight commit, and fix(hindsight): surface retain timeouts clearly #59842 additionally labels the timed-out operation.
• The compression guard is already superseded on main by 3804df5b3, which includes the same non-object argument normalization plus a broader never-raises backstop and hostile-input regression matrix.

No remaining unique hunk needs to be ported, and no target branch was changed during this consolidation.

Validation

• Current main hostile tool-argument matrix: 35 passed.
• fix: harden subprocess env handling (scrub secrets, isolate browser sessions) #59840 focused snapshot/env tests: 42 passed.
• fix(hindsight): surface retain timeouts clearly #59842 focused Hindsight provider tests: 118 passed.
• Hindsight stable patch-id equality verified between this PR and fix(hindsight): surface retain timeouts clearly #59842.

Notes

This is a consolidation close, not a rejection of the fixes. The maintained destinations are #59840, #59842, and main commit 3804df5b3.

Refs

• fix: harden subprocess env handling (scrub secrets, isolate browser sessions) #59840
• fix(hindsight): surface retain timeouts clearly #59842
• 3804df5b36aeb2fcb6ae1c2bc38dd53f46c4de01