Add CLI arguments for UserMessages settings overrides

- Add --ignore-user-messages, --ignore-pre-action-messages, and
  --ignore-post-action-messages CLI arguments to the spec
- Define precedence: CLI arguments override settings
- Clarify distinction from --disable-interactivity (suppresses prompt
  only vs. suppresses message entirely)
- Update Copilot instructions: when adding settings, always consider
  corresponding CLI arguments (and vice versa)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: denelon

.github/instructions/specs.instructions.md

@@ -74,6 +74,7 @@ A complete specification should address all areas the feature touches. For WinGe
 - **COM API** — `Microsoft.Management.Deployment` interfaces and WinRT projections
 - **PowerShell cmdlets** — `Install-WinGetPackage`, `Update-WinGetPackage`, `Uninstall-WinGetPackage`, `Repair-WinGetPackage`, `Find-WinGetPackage`, `Show-WinGetPackage`
 - **Settings** — User settings in `settings.json` (see `doc/Settings.md`)
+- **CLI arguments** — When adding a new setting, also consider a corresponding CLI argument (and vice versa). Settings define defaults; arguments provide per-invocation overrides.
 - **Manifest schema** — JSON schema files in `schemas/JSON/manifests/`
 - **Validation** — The winget-pkgs community repository validation pipeline
 - **WinGet Configuration / DSC** — Declarative configuration flows

doc/specs/#3483 - UserMessages.md

@@ -201,6 +201,27 @@ The following table shows what is displayed on **clients that support `UserMessa
 
 On **older clients** that do not support `UserMessages`, only `InstallationNotes` is relevant and `disableInstallNotes` controls it as it does today.
 
+### CLI Arguments
+
+Corresponding CLI arguments are provided so users can override the settings on a per-invocation basis.
+
+| Argument | Applies to | Description |
+|----------|-----------|-------------|
+| `--ignore-user-messages` | `install`, `upgrade`, `uninstall`, `repair`, `import` | Suppresses all `UserMessages` (both pre- and post-action) for this invocation. Pre-action prompts are skipped and the operation proceeds. |
+| `--ignore-pre-action-messages` | `install`, `upgrade`, `uninstall`, `repair`, `import` | Suppresses pre-action messages and their prompts for this invocation. Post-action messages are still shown. |
+| `--ignore-post-action-messages` | `install`, `upgrade`, `uninstall`, `repair`, `import` | Suppresses post-action messages for this invocation. Pre-action messages and prompts are still shown. |
+
+**Precedence:** CLI arguments override settings. If a user has `userMessages.disablePreActionMessages` set to `false` in settings but passes `--ignore-pre-action-messages`, the pre-action messages are suppressed for that invocation.
+
+**Relationship to `--disable-interactivity`:** The `--disable-interactivity` flag suppresses the **prompt** on pre-action messages but still displays the message text. The `--ignore-pre-action-messages` flag suppresses both the message and the prompt entirely.
+
+Example usage:
+
+```
+winget upgrade --all --ignore-pre-action-messages
+winget install Publisher.ExampleApp --ignore-user-messages
+```
+
 ### COM API
 
 The COM API must surface `UserMessages` in a structured manner for programmatic consumers.