Expose a public general-purpose CLI error after vendoring Click

[ldlda]

Feature Request

Expose a public, general-purpose Typer exception for concise user-facing CLI
errors after Click vendoring.

Typer 0.26.0 intentionally vendored Click and no longer supports using Click
directly. This is documented in the 0.26.0 breaking changes and the Vendored
Click guide. This request is not asking to restore compatibility with exception
classes imported from the external click package.

Current API Gap

Typer publicly re-exports several vendored exception types, including
typer.BadParameter, typer.Abort, and typer.Exit, but it does not expose a
general-purpose typer.ClickException or typer.UsageError equivalent.

Before 0.26.0, an application could raise click.ClickException("broken") to
produce Typer's concise error panel and exit with code 1. After vendoring, the
supported public workaround is to write and terminate separately:

typer.echo("Error: broken", err=True)
raise typer.Exit(code=1)

This works, but each application must reproduce the error prefix, output
stream, formatting policy, and exit behavior instead of expressing one typed
CLI error.

typer.Abort is not an equivalent because it represents user cancellation and
adds Aborted! output.

Proposed API

Expose the vendored general-purpose exception through Typer's public namespace,
or provide a Typer-native equivalent:

import typer

app = typer.Typer()


@app.command()
def fail() -> None:
    raise typer.ClickException("broken")

Expected output should use Typer's standard concise error formatting and be
captured by typer.testing.CliRunner on stderr.

The exact public name is not important. A Typer-native UsageError or another
documented general-purpose CLI error would satisfy the same need.

Why This Is Distinct From Existing Exports

• typer.BadParameter describes parameter validation and requires parameter
  context for its best output.
• typer.Abort describes cancellation and prints Aborted!.
• typer.Exit controls termination but carries no error message or formatting.

A general-purpose error is useful when adapting failures from HTTP clients,
RPC calls, configuration loading, or other application services at the CLI
boundary.

Version Context

• Typer 0.25.0 with external Click: click.ClickException produced concise
  output.
• Typer 0.26.0 and newer: direct Click use is intentionally unsupported.
• Typer 0.26.8 and master at b210c0e2: no public general-purpose Typer
  exception is exported.

Test environment: Python 3.14.3 on Windows 11.

[Nikhileswar21]

Hey! Lemme work on this issue..