Port from openai/codex#31494: user-visible history replay must strip CSI
sequences and control characters. Stored conversation history can carry
raw terminal escapes (pasted content, gateway-origin text, model output
echoing injected tool results). Replaying it via /resume's recap panel or
build_recap (/status on CLI + gateway) wrote those bytes straight to the
terminal — an injected message could clear the screen, retitle the window,
move the cursor, or restyle the recap UI. Rich's Text() does not neutralize
raw escape bytes.
- tools/ansi_strip.py: add sanitize_display_text() — strip_ansi() plus
bare C0/C1 control removal, preserving \n and \t, normalizing \r to \n
(adapted to Python from Codex's sanitize_user_text; reuses the existing
ECMA-48 stripper instead of transcribing their char-walk)
- hermes_cli/cli_agent_setup_mixin.py: sanitize user + assistant text in
_display_resumed_history() before building the Rich recap panel
- hermes_cli/session_recap.py: sanitize preview lines in build_recap()
(_truncate choke point) so /status recaps are clean on every platform
- tests: 10 new sanitize_display_text cases (incl. the exact codex#31494
fixture), recap + resume-display leak assertions
Root cause: terminal_tool, execute_code, and process_registry returned raw
subprocess output with ANSI escape sequences intact. The model saw these
in tool results and copied them into file writes.
Previous fix (PR #2532) stripped ANSI at the write point in file_tools.py,
but this was a band-aid — regex on file content risks corrupting legitimate
content, and doesn't prevent ANSI from wasting tokens in the model context.
Source-level fix:
- New tools/ansi_strip.py with comprehensive ECMA-48 regex covering CSI
(incl. private-mode, colon-separated, intermediate bytes), OSC (both
terminators), DCS/SOS/PM/APC strings, Fp/Fe/Fs/nF escapes, 8-bit C1
- terminal_tool.py: strip output before returning to model
- code_execution_tool.py: strip stdout/stderr before returning
- process_registry.py: strip output in poll/read_log/wait
- file_tools.py: remove _strip_ansi band-aid (no longer needed)
Verified: `ls --color=always` output returned as clean text to model,
file written from that output contains zero ESC bytes.
