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Say which versions the round trip spans, and stop overstating the canary - #1

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fix/version-span-and-canary-claim
Aug 2, 2026
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Say which versions the round trip spans, and stop overstating the canary#1
nerln merged 1 commit into
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fix/version-span-and-canary-claim

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@nerln nerln commented Aug 2, 2026

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Four claims in the published docs did not survive checking against the artifacts on disk.

Claim What is actually true
Round trip verified on Claude Code 2.1.220 2.1.219 wrote the source transcripts, 2.1.220 resumed the transferred session
transcode.py says formats checked on 2.1.207 Contradicted the README. Now matches
Canary asks both agents to recall markers "without file access" Not enforced. It is an instruction in the prompt; the Codex sandbox still permits reads and Claude has no tool restriction
Both target files remained 0600 after native resume True of what this tool writes. When Codex resumes one it forks a new rollout under its own umask, world readable, with the same conversation in it

The supported version prefix gate is unchanged, so behaviour does not change. pytest tests/ passes, 68 tests.

🤖 Generated with Claude Code

The README claimed the round trip was verified on Claude Code 2.1.220. The
source transcripts were written by 2.1.219; 2.1.220 is the version that resumed
the transferred session. The build session records 2.1.219 on all 951 versioned
lines and the target session records 2.1.220 on all 26.

transcode.py still said the formats were checked on 2.1.207, in the docstring
and in CLAUDE_VERSION_FALLBACK, which contradicted the README for anyone who
opened the source. The supported prefix gate is unchanged.

The canary was described as asking both agents to recall markers with no file
access. Nothing enforces that. The restriction is text in the prompt, Codex runs
under a read-only sandbox that still permits reads, and Claude runs with no tool
restriction. Say what it actually does.

The 0600 note was true of the files this tool writes and misleading about what
happens next: when Codex resumes one of those targets it forks a new rollout
under its own umask, world readable, holding the same conversation.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Copilot AI review requested due to automatic review settings August 2, 2026 03:33

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Pull request overview

Updates published documentation and in-repo script headers to reflect empirically verified version spans and to avoid overstating the guarantees of the verify-drift.py compatibility canary (notably, “no file access” is a prompt instruction rather than an enforced sandbox/tool restriction).

Changes:

  • Clarifies the end-to-end macOS verification statement to span Claude Code 2.1.2192.1.220, and tightens the 0600 claim to “files this tool wrote” while noting Codex’s resumed fork behavior.
  • Rewords the tools/verify-drift.py canary description to describe the “no-reading” constraint as an instruction rather than an enforced restriction.
  • Updates transcode.py’s documented “verified formats” versions and bumps CLAUDE_VERSION_FALLBACK.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File Description
skills/switch-agent/scripts/transcode.py Updates the script’s documented verified versions and adjusts the Claude fallback version constant.
README.md Corrects/clarifies verification claims (version span, file permissions nuance) and explains canary limitations around file-reading enforcement.

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CODEX_HOME = Path(os.environ.get("CODEX_HOME") or (Path.home() / ".codex"))

CLAUDE_VERSION_FALLBACK = "2.1.207"
CLAUDE_VERSION_FALLBACK = "2.1.220"
@nerln
nerln merged commit e6d702c into main Aug 2, 2026
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@nerln
nerln deleted the fix/version-span-and-canary-claim branch August 2, 2026 15:35
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2 participants