[BUG] PreToolUse hooks not triggered for @file reference reads

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

@-referencing a file (e.g., @/tmp/some-file.txt) loads the file content
into conversation context without triggering any PreToolUse hooks. The
system-reminder shows "Called the Read tool" but the hook never fires — no log
entry, no chance to block.

This affects any PreToolUse hook with a Read or * matcher. Any hook that
needs to intercept file reads — logging, access control, auditing — is
completely bypassed by @ file references.

A previous report of this issue (#9407) was auto-closed after 60 days without
human triage and is now locked.

What Should Happen?

Either:

1. @ file reads should trigger PreToolUse hooks like any other Read tool call, or
2. A new hook event (e.g., PreFileAttach) should be provided so hooks/plugins

can intercept file attachments before they enter the conversation context.

While @ references are user-initiated, hook authors should have the option
to enforce policies uniformly across all file-reading pathways.

Error Messages/Logs

Using the logging hook from the repro steps below, hook-log.txt shows the
gap — no entry for the @ read, but a direct Read is logged:

# After @-referencing a file: no entry appears in hook-log.txt

# After asking Claude to "read /tmp/some-file.txt" directly:
$ cat hook-log.txt
Sun Mar 15 10:42:01 PDT 2026 tool=Read

Steps to Reproduce

1. Create a PreToolUse hook that logs all invocations to a file:

``json
{
"hooks": {
"PreToolUse": [{
"matcher": "*",
"hooks": [{
"type": "command",
"command": "echo \"$(date) tool=$TOOL_NAME\" >> hook-log.txt && cat"
}]
}]
}
}
``

1. Start a new Claude Code session
2. Type @path-to-file (any file outside the project directory) in the prompt
3. Observe: file content appears in conversation context, but hook-log.txt

has no entry for a Read tool call

1. Compare: ask Claude to "read that same path" — the hook fires, an entry

appears in the log, and the hook can block the operation

Claude Model

Not sure / Multiple models

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Unknown — the change likely occurred around v2.1.20 which changed @ references
to "show as removable attachments instead of inserting text"

Claude Code Version

2.1.50

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

• Prior issue: #9407 (auto-closed by inactivity bot, locked, never triaged by a human)
• The @ file reference appears in system-reminder tags as "Called the Read tool"

suggesting it uses the Read tool internally, but the PreToolUse hook pipeline
is not invoked for this code path

• This affects hooks configured in both .claude/settings.json and plugin hooks.json