eval: refuse dead-session attach without restart - #42
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myobie merged 2 commits intoJul 30, 2026
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agent-session-id: a078daee-6f98-4916-91a8-d21291407789 agent-tool: Codex CLI agent-tool-version: 0.145.0 agent-model: unknown agent-runtime-profile: /nix/store/mnx8agbdq3wiyb6vz63lhgscgazkrn98-coding-agent-runtime-profile/share/coding-agents/profile.json agent-skills-manifest: /nix/store/5r69m9k2llmri3na81518zx0a7y0d3cn-agent-skills-corpus/share/agent-skills/manifest.json tooling-profile: dotfiles@0fb7e03
schickling
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July 30, 2026 08:30
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agent-session-id: a078daee-6f98-4916-91a8-d21291407789 agent-tool: Codex CLI agent-tool-version: 0.145.0 agent-model: unknown agent-runtime-profile: /nix/store/mnx8agbdq3wiyb6vz63lhgscgazkrn98-coding-agent-runtime-profile/share/coding-agents/profile.json agent-skills-manifest: /nix/store/5r69m9k2llmri3na81518zx0a7y0d3cn-agent-skills-corpus/share/agent-skills/manifest.json tooling-profile: dotfiles@0fb7e03
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Why
A relay that intends to attach only to an existing PTY daemon can currently land on the dead-session
Restart? [Y/n]prompt. Later input intended for the target is then consumed as restart consent and evaluates retained launch metadata. This guards the explicit attach-only contract implemented by compoundingtech/pty#123 for issue compoundingtech/pty#122.Public reproduction: https://github.com/schickling-repros/2026-07-pty-attach-only-mode/tree/schickling-assistant/2026-07-30-pty-attach-only-mode
What
Add a model-free
pty-attach-onlycell using synthetic sessions in an eval-owned PTY root. It proves all three sides of the policy: attach-only works against a live daemon, legacy attach still demonstrates the dangerous dead-session restart, and attach-only refuses a dead daemon without interaction or a new incarnation.How
The held-out judges require:
--no-restarthelp surface, so an unknown-option error cannot fake safety;live-input->LIVE-ACK:live-input) with one incarnation;session_startevent after both candidate attaches;exitedstate without a matching live daemon;The generated catalog and model-free harness exclusion inventory are updated. No provider/model call is involved.
Verification
Against exact PTY PR #123 head
36547b02c32116cca81df4147a638da7df6981a5(PTY 0.12.0, artifact SHA-256406fbfcc6e292bcd178be15470e0fc8310ba1ddc35becbab25e0cffd0f096334):st2 eval ./cells/pty-attach-only/ --keep— PASS, 8 PASS / 0 FAIL / 8 gating judgesbin/check-kdl-parse.sh— PASS (67 KDL files)bin/check-st2-semantic.sh— PASS (44 folder evals, 9 nested catalogs)bin/check-harness-contract.sh— PASS (13 model-free cells)bin/check-overnight-policy.sh— PASS (44-cell inventory)bin/check-no-pii.sh/bin/check-no-pii-history.sh— PASSbin/generate-catalog.sh --check— PASSThe complete free preflight separately reaches the unchanged
inbox-hygienefixture-reset check, which currently reports deletedPROCESSED.log; the new cell-specific and downstream inventory/isolation gates above pass.Rationale
Keeping this model-free makes the lifecycle invariant deterministic, cheap, and suitable for every PTY/st2 integration change. The explicit live and legacy controls prevent vacuous refusal tests, while exact bounded terminal transcripts reject interactive confirmation variants.
Posted on behalf of @schickling
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