[Bug]: Commands that Claude Code mods register never appear in the / menu #17418

Before submitting

• I searched existing issues and did not find a duplicate.
• I included enough detail to reproduce or investigate the problem.

Area

• apps/server

Steps to reproduce

1. Install a Claude Code mod that registers a slash command in its session.start hook with $.command.register(...). Example: a mod that registers /handoffs.
2. Confirm that the command works in the Claude Code CLI (2.1.295):

   claude -p "/handoffs" --output-format stream-json --verbose --max-turns 1

   The system/init message lists the plugin in plugins, and handoffs is in slash_commands. The command runs and returns its reply.
3. Open a Claude thread in T3 Code and type /hand in the composer.

Expected behavior

The / menu shows the commands that installed mods register, as it does for skills and .claude/commands.

Actual behavior

The / menu does not show mod commands.

The cause is the periodic Claude capabilities probe. It sets settings: { disableAllHooks: true } (apps/server/src/provider/ClaudeProvider.ts:203, added in #4466 so that probes do not run the user's SessionStart hooks). That setting also turns off mod hooks, so the mod's session.start handler never runs and the command is never registered. To confirm:

claude -p "/handoffs" --settings '{"disableAllHooks":true}' --output-format stream-json --verbose --max-turns 1

With hooks off, plugins still lists the mod, but handoffs is missing from slash_commands. Claude sends /handoffs to the model as a normal prompt.

Real chat sessions do not turn off hooks. If the user types the full command and sends it, it should still run. Only discovery in the menu is broken.

#4466 was merged before Claude Code turned mods on by default (v2.1.287).

Impact

• Minor bug or occasional failure

Version or commit

main @ 2c7a446

Environment

macOS 26.6, Claude Code 2.1.295, @anthropic-ai/claude-agent-sdk 0.3.276

Logs or stack traces

No response

Screenshots, recordings, or supporting files

No response

Workaround

Type the full command name and send it. The live session has hooks on, so the command should run without the menu.

Related

• feat(claude): draw Claude Code plugin status lines, toasts and prompt band #15827 shows mod status lines, toasts, and the prompt band. It does not change the / menu.
• [Bug]: Workspace snapshot taken before the first Claude probe finishes leaves the / menu without provider commands for the whole session #11575 and [Bug]: Project .claude/commands/*.md never appear in the / menu for Claude; the per-workspace refresh only scans .claude/skills #12214 are other cases of missing / menu commands, with different causes.
• Discussion Support and integration for Claude mods #14956 asks for general Claude mods support.