HyperlinkMapOutOfMemory error during split zoom causes process termination

[paskal]

Issue Description

When toggling split zoom (Cmd+Shift+Enter) in a terminal running Claude Code CLI (a Node.js TUI that outputs many OSC 8 hyperlinks), the child process is killed.

Steps to reproduce:

1. Open Ghostty with splits (Cmd+D)
2. Run claude (Claude Code CLI) in one split
3. Load a long conversation with many hyperlinks (via /resume)
4. Expand the split (Cmd+Shift+Enter)
5. Unexpand the split (Cmd+Shift+Enter again)
6. Result: Claude process is killed, terminal shows shell prompt

Error from unified log:

2026-01-15 21:41:27.893332 [page_list] adjusting page capacity=terminal.page.Capacity{ .cols = 83, .rows = 572, .styles = 128, .hyperlink_bytes = 2048, .grapheme_bytes = 8192, .string_bytes = 4096 }
2026-01-15 21:41:27.894644 [io_thread] error during resize err=error.HyperlinkMapOutOfMemory

The resize operation (169 cols → 83 cols, 277 rows → 572 rows) causes the HyperlinkMap to run out of memory, which then causes process termination.

Additional debugging evidence:

• No memory spike in the child process before death (stable at ~150-200MB)
• No crash reports generated (neither node nor Ghostty)
• Signal traps don't fire (tested SIGHUP/SIGTERM/SIGINT via wrapper scripts)
• Process receives uncatchable termination (SIGKILL or PTY destruction)

Expected behaviour:
Resize errors should be handled gracefully without killing the child process. The HyperlinkMap should either grow to accommodate the resize, or the error should not cause process termination.

Notes:
Claude Code outputs many OSC 8 hyperlinks for file paths, which likely causes hyperlink_bytes to grow. The combination of many hyperlinks + dramatic resize during zoom toggle leads to allocation failure and process death.

Expected Behavior

When toggling split zoom (Cmd+Shift+Enter), the terminal should resize without affecting running processes. The child process should continue running normally.

Actual Behavior

When toggling split zoom after outputting many OSC 8 hyperlinks, the child process is killed. The terminal shows the shell prompt as if the process exited. The unified log shows: [io_thread] error during resize err=error.HyperlinkMapOutOfMemory

Reproduction Steps

Note: Unable to create minimal reproduction outside of Claude Code

1. Run Claude Code (Node.js TUI application using ink)
2. 2. Load a large session with /resume (56MB session file, ~1000 file path hyperlinks)
3. 3. Scroll up in the terminal to view scrollback
4. 4. Toggle split zoom with Cmd+Shift+Enter
      The issue appears to be specific to long Claude Code sessions with many OSC 8 hyperlinks in scrollback. We attempted to reproduce with shell scripts outputting similar hyperlink patterns but could not trigger the crash.

Update: Unable to reproduce this issue in tip (commit 26e243a, build 13862). Reporting for awareness in case it helps with related issues.

Ghostty Logs

**Sentry UUIDs (submitted):**
- `9231a942-8891-42b6-8858-c41a93cfa8e8` (Dec 21)
- `6bd704ac-a8b9-49a4-1d5a-22ee9c9fc75a` (Jan 9)
- `84e10954-cd67-418f-6bd3-74572f62a905` (Jan 11)
- `47cdd150-eaad-4c6f-5b40-71543d1dc0f1` (Jan 13)
- `60ff1007-d7a3-4881-c661-a683abeb787f` (Jan 15)

**Unified log captured during crash:**

[page_list] adjusting page capacity=terminal.page.Capacity{ .cols = 83, .rows = 572, .styles = 128, .hyperlink_bytes = 2048, .grapheme_bytes = 8192, .string_bytes = 4096 }
[io_thread] error during resize err=error.HyperlinkMapOutOfMemory

### Ghostty Version

```text
Ghostty 1.2.3

Version
  - version: 1.2.3
  - channel: stable
Build Config
  - Zig version   : 0.14.1
  - build mode    : builtin.OptimizeMode.ReleaseFast
  - app runtime   : apprt.Runtime.none
  - font engine   : font.main.Backend.coretext
  - renderer      : renderer.generic.Renderer(renderer.Metal)
  - libxev        : kqueue

OS Version Information

macOS 15 (Darwin 25.2.0) - Apple Silicon

(Linux only) Display Server

None

(Linux only) Desktop Environment/Window Manager

No response

Minimal Ghostty Configuration

window-padding-x=5
window-padding-y=5
copy-on-select=clipboard
macos-option-as-alt=true
shell-integration-features = cursor, sudo, title, ssh-env, ssh-terminfo

Additional Relevant Configuration

No response

I acknowledge that:

• I have reviewed the FAQ and confirm that my issue is NOT among them.
• I have searched the Ghostty repository (both open and closed Discussions and Issues) and confirm this is not a duplicate of an existing issue or discussion.
• I have checked the "Preview" tab on all text fields to ensure that everything looks right, and have wrapped all configuration and code in code blocks with a group of three backticks (```) on separate lines.

[t-mdo]

Exact same issue. Happens to me when i minimize the split claude code is in after maximizing it. Only happens with a long claude code discussion.

CleanShot.2026-01-16.at.14.43.30.mp4

[mitchellh]

This should be fixed from #10337 on tip. Please let me know if not, but this error is no longer possible during resize.

[t-mdo]

perfect, thanks!