[FEATURE] Session titles should be user-locked and never auto-updated

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

When a user explicitly names a session topic at the start of a
conversation, Claude Code auto-updates that title as the conversation
evolves, overwriting the user's intent with whatever the AI thinks
the session is currently "about."

This makes past sessions impossible to find by topic. A session
named "WIP Report Rebuild" gets renamed to something like "Email
Formatting" if that sub-topic comes up late in the conversation.
The original topic — the one the user cared about — is lost.

Proposed Solution

If a user explicitly sets or types a session title, that title is
locked and never auto-updated. Auto-titling should only apply to
sessions where the user has never set a title manually.

This should be the default behavior, with opt-in auto-titling
for users who prefer it — not the other way around.

Alternative Solutions

A simple lock icon next to the session title that the user can
click to freeze it. Or a setting in settings.json:
"autoUpdateSessionTitles": false

Priority

High - Significant impact on productivity

Feature Category

CLI commands and flags

Use Case Example

_No response_

Additional Context

A simple workaround would be a settings.json option:
"autoUpdateSessionTitles": false