webterm/docs/tmux-da-response-filtering.md

Fix for "1;10;0c" Display Issue in tmux

Problem

When entering or refreshing a webterm session running tmux, the text "1;10;0c" appears on the screen. This is a terminal Device Attributes (DA) response that should be filtered out.

Root Cause

1. Tmux sends a DA2 query (ESC[>c) when it initializes to detect terminal capabilities
2. The terminal responds with ESC[>1;10;0c (DA2 response format)
3. The filtering code only handled DA1 responses (ESC[?...c) but not DA2 (ESC[>...c)
4. The unfiltered DA2 response appeared as visible text "1;10;0c" in the replay buffer

Solution

Updated the DA response filtering patterns in three files to handle all DA variants:

• DA1 (Primary): ESC[?...c - already handled ✓
• DA2 (Secondary): ESC[>...c - NOW FIXED ✓
• DA3 (Tertiary): ESC[=...c - added for completeness ✓

Changed Files

1. src/webterm/terminal_session.py
2. src/webterm/docker_exec_session.py
3. src/webterm/local_server.py

Pattern Changes

Before:

DA_RESPONSE_PATTERN = re.compile(rb"\x1b\[\?[\d;]+c")
DA_PARTIAL_PATTERN = re.compile(rb"\x1b(?:\[(?:\?[\d;]*)?)?$")

After:

DA_RESPONSE_PATTERN = re.compile(rb"\x1b\[[?>=][\d;]*c")
DA_PARTIAL_PATTERN = re.compile(rb"\x1b(?:\[(?:[?>=][\d;]*)?)?$")

Testing

• All 342 existing tests pass ✓
• Verified the pattern matches DA1, DA2, and DA3 responses ✓
• Confirmed partial buffering works for all variants ✓

Technical Details

Device Attributes queries/responses:

• DA1: ESC[c → ESC[?1;10;0c (terminal capabilities)
• DA2: ESC[>c → ESC[>1;10;0c (terminal version - sent by tmux)
• DA3: ESC[=c → ESC[=1;0c (rarely used)

The fix ensures all three variants are filtered from both live output and replay buffers when clients reconnect.