Harden the PTY proxy, add a session summary, and support Python 3.10+ by Vaibhavtripathi7 · Pull Request #1 · Vaibhavtripathi7/context_kernel

Vaibhavtripathi7 · 2026-06-20T08:37:44Z

Overview

Reliability and security hardening of the PTY interceptor, a visible end-of-session savings summary, wider Python support, and full docs.

Changes

Added an end-of-session summary showing chunks pruned, tokens saved, an estimated cost, and elapsed time.
The terminal is now restored and the child is signalled when ACK is killed with SIGTERM or SIGHUP.
Fixed a 100% CPU busy-loop that occurred when stdin reached EOF or the agent sat idle.
A traceback that spans several PTY reads is now held and pruned as one unit instead of being half-compressed.
Injected summaries use CRLF in raw mode, so they no longer print as a staircase.
ACK now exits with code 127 and a clear message when the wrapped command does not exist.
Stored output is stripped of terminal escape sequences before it is printed, closing a terminal-hijack vector.
The session summary no longer crashes when its output is piped to a consumer that closes early.
Each prunable block is now matched once instead of twice.
Lowered the supported Python floor to 3.10 and run CI across 3.10-3.13.
Corrected the repository URL in the package metadata.
Added a complete README with a demo GIF and an architecture diagram.

Impact

Idle/piped CPU: ~98% to ~0%.
Tracebacks and floods compress cleanly end to end; ~95% token compression at 100% signature fidelity.
Installable on Python 3.10-3.13 (was 3.13 only).
Closes a terminal-hijack vector from displaying stored output.

Tests

97 tests pass (unit + integration).
ruff + mypy --strict clean.
Compression benchmark green; CI across Python 3.10-3.13.

The repository field pointed at a non-existent slug; update it to the actual GitHub remote so clone instructions and PyPI links resolve.

ACK uses no 3.11+ syntax, so lower the floor from 3.13 to 3.10 to widen the installable audience. Add the 3.10-3.12 trove classifiers, retarget ruff and mypy to py310, refresh the lock file, and run CI across 3.10-3.13.

When the wrapped agent exits, print a short summary to stderr: chunks intercepted/pruned, tokens saved (with a rough cost estimate), and elapsed time. Makes the value of a session visible at a glance. Skipped under --no-annotate and in the TUI (which shows live stats).

The terminal's NL->CRLF mapping (OPOST) is disabled while ACK holds the TTY in raw mode, so the bare newlines in our injected summaries printed as a staircase. Child passthrough already carries CRLF from its own PTY, so convert only the text ACK generates, and only while raw.

A traceback larger than the kernel's PTY buffer arrives in several reads. ACK was pruning the first fragment (no exception line yet) and passing the rest through raw. Hold a buffer whose traceback has not reached its exception line until it completes (bounded by max_buffer_bytes), and condense a repetitive preamble that shares the buffer with it.

With stdin at EOF (piped input, /dev/null, CI) select reported it readable forever, burning ~100% CPU. Drop stdin from the watch set once it reaches EOF, and block in select() with no timeout while nothing is buffered so the loop is idle at ~0% CPU instead of polling.

execvp raised straight through the forked child, dumping a Python traceback and a misleading exit code. Catch the OSError, print a short 'cannot run ...' message, and exit 127.

If ACK was killed by a signal the shell was left stuck in raw mode and the child orphaned. Install handlers that restore the terminal, forward the signal to the child's process group, and exit 128+signum. Guard the install for the main thread only (the --tui worker thread cannot set signal handlers), which also fixes a latent crash in that mode.

The flush loop called pruner.matches() and then compress(), but compress() already self-gates with matches() internally. Call compress() directly so a pruned block is matched once instead of twice.

When ACK output is piped to a consumer that exits early (e.g. '... 2>&1 | head'), the summary's echo hit a BrokenPipeError. Guard it so a closed downstream never masks the agent's real exit code.

ack search/sessions echoed stored raw_content verbatim, which still holds the agent's original escape sequences. A captured mouse/app-mode toggle could reprogram the reader's terminal (runaway output, dead Ctrl-C). Sanitise escape and control characters before printing; raw bytes stay untouched in the database.

Rework the example into a paced build-and-test simulation: status lines pass through, a 200-line log flood collapses to a frequency table, and a deep traceback buried under framework frames collapses to the exception plus the user frames. Short pauses keep each phase readable.

Vaibhavtripathi7 added 13 commits June 18, 2026 23:21

fix: correct repository URL in package metadata

985d353

The repository field pointed at a non-existent slug; update it to the actual GitHub remote so clone instructions and PyPI links resolve.

build: support Python 3.10+

2965166

ACK uses no 3.11+ syntax, so lower the floor from 3.13 to 3.10 to widen the installable audience. Add the 3.10-3.12 trove classifiers, retarget ruff and mypy to py310, refresh the lock file, and run CI across 3.10-3.13.

fix(orchestrator): exit cleanly when the agent command is not found

79fa1ef

execvp raised straight through the forked child, dumping a Python traceback and a misleading exit code. Catch the OSError, print a short 'cannot run ...' message, and exit 127.

perf(orchestrator): skip the redundant pruner match pass

c216a71

The flush loop called pruner.matches() and then compress(), but compress() already self-gates with matches() internally. Call compress() directly so a pruned block is matched once instead of twice.

fix(cli): do not crash the session summary on a closed pipe

fa4c65c

When ACK output is piped to a consumer that exits early (e.g. '... 2>&1 | head'), the summary's echo hit a BrokenPipeError. Guard it so a closed downstream never masks the agent's real exit code.

docs: add full README with demo gif and architecture diagram

f4caf1c

Vaibhavtripathi7 merged commit 9d9fb07 into main Jun 20, 2026
4 checks passed

Vaibhavtripathi7 deleted the hardening branch June 20, 2026 08:47

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Harden the PTY proxy, add a session summary, and support Python 3.10+ - #1

Harden the PTY proxy, add a session summary, and support Python 3.10+#1
Vaibhavtripathi7 merged 13 commits into
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Vaibhavtripathi7 commented Jun 20, 2026 •

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Vaibhavtripathi7 commented Jun 20, 2026 •

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