Both places a user learns the `specify self upgrade --tag` syntax silently drop
the `[suffix]` token, because Rich parses the literal square brackets as a
markup tag and discards them:
rejected tag -> "Invalid --tag: expected vMAJOR.MINOR.PATCH"
(constant is "Invalid --tag: expected vMAJOR.MINOR.PATCH[suffix]")
--help -> "Pin the target version (vX.Y.Z). Without --tag, ..."
So the CLI implies a bare vX.Y.Z is the ONLY accepted form, when v1.0.0-rc1,
v0.8.0.dev0 and v0.8.0+build.42 are all valid -- and the shipped docs advertise
the suffix in four places (docs/upgrade.md x3, README.md x2).
Escape the rejection message at the PRINT site rather than baking `\[` into
_INVALID_TAG_MESSAGE: the same constant is raised through typer.BadParameter,
which Click renders without Rich, so it must stay plain text. Escape the literal
bracket in the option help, which Typer renders through Rich.
Same literal-bracket class as the existing precedents in workflows/_commands.py
(`\[disabled]`, `\[<type>]`). Static CLI text only -- no validation semantics
change and `_validate_tag` is untouched.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>
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