Add 'ghost upgrade' command to self-upgrade the CLI

CLAUDE.md

@@ -4,7 +4,7 @@
 
 - **`cmd/`** - Binary entry points. Contains `ghost/main.go` (the main CLI binary, which sets up context/signal handling and delegates to the internal command infrastructure), `npm-publisher/` (a CI tool that generates and publishes npm packages for each platform), and `generate-docs/` (generates Markdown CLI reference docs to `docs/cli/`).
 - **`internal/`** - All core application logic (non-public Go packages).
-  - **`internal/cmd/`** - Cobra command implementations for all CLI commands (create, fork, list, delete, pause, resume, connect, psql, sql, schema, logs, password, rename, status, feedback, api-key, login, logout, config, mcp, version, completion, payment). Each command lives in its own file, named to match the command in snake_case (e.g. `ghost payment list` → `payment_list.go`). Helper files like `completion.go`, `errors.go`, and `logger.go` contain shared utilities. Commands that are not yet ready for public release can be gated behind the `GHOST_EXPERIMENTAL` env var (see `internal/common/app.go`'s `App.Experimental` field).
+  - **`internal/cmd/`** - Cobra command implementations for all CLI commands (create, fork, list, delete, pause, resume, connect, psql, sql, schema, logs, password, rename, status, feedback, api-key, login, logout, config, mcp, version, upgrade, completion, payment). Each command lives in its own file, named to match the command in snake_case (e.g. `ghost payment list` → `payment_list.go`). Helper files like `completion.go`, `errors.go`, and `logger.go` contain shared utilities. Commands that are not yet ready for public release can be gated behind the `GHOST_EXPERIMENTAL` env var (see `internal/common/app.go`'s `App.Experimental` field).
   - **`internal/api/`** - API client layer. Includes an OpenAPI-generated REST client (`client.go`, `types.go`), shared HTTP client singleton, and request/response types. **Do not edit `client.go` or `types.go` by hand** — they are generated from `openapi.yaml` (see [Code Generation](#code-generation)). The `mock/` subdirectory contains a generated mock of `ClientWithResponsesInterface` for use in tests.
   - **`internal/config/`** - Configuration management. Handles config file loading (via Viper), credential storage (keyring with file fallback), and version checking.
   - **`internal/common/`** - Shared business logic used across commands and MCP tools. Includes API client initialization, database connection/schema/query utilities, error handling with exit codes, and version update checks.

README.md

@@ -79,6 +79,7 @@ ghost list        # List all databases
 | `schema` | Display database schema information |
 | `sql` | Execute SQL query on a database |
 | `status` | Show space usage |
+| `upgrade` | Upgrade the ghost CLI to the latest version |
 | `version` | Show version information |
 
 Run `ghost [command] --help` for more information about a command.

docs/cli/ghost.md

@@ -45,5 +45,6 @@ Ghost is a command-line interface for managing PostgreSQL databases.
 * [ghost schema](ghost_schema.md)	 - Display database schema information
 * [ghost sql](ghost_sql.md)	 - Execute SQL query on a database
 * [ghost status](ghost_status.md)	 - Show space usage
+* [ghost upgrade](ghost_upgrade.md)	 - Upgrade the ghost CLI to the latest version
 * [ghost version](ghost_version.md)	 - Show version information
 

docs/cli/ghost_upgrade.md

@@ -0,0 +1,39 @@
+---
+title: "ghost upgrade"
+slug: "ghost_upgrade"
+description: "CLI reference for ghost upgrade"
+---
+
+## ghost upgrade
+
+Upgrade the ghost CLI to the latest version
+
+### Synopsis
+
+Download and install the latest published version of the ghost CLI, replacing the currently running binary.
+
+If ghost was installed via a package manager (Homebrew, apt, yum/dnf), the upgrade will be refused with a suggestion to use that package manager instead.
+
+```
+ghost upgrade [flags]
+```
+
+### Options
+
+```
+  -h, --help   help for upgrade
+```
+
+### Options inherited from parent commands
+
+```
+      --analytics           enable/disable usage analytics (default true)
+      --color               enable colored output (default true)
+      --config-dir string   config directory (default "~/.config/ghost")
+      --version-check       check for updates (default true)
+```
+
+### SEE ALSO
+
+* [ghost](ghost.md)	 - CLI for managing Postgres databases
+

internal/cmd/root.go

@@ -120,6 +120,7 @@ func buildRootCmd() (*cobra.Command, *common.App, error) {
 	cmd.AddCommand(buildRenameCmd(app))
 	cmd.AddCommand(buildApiKeyCmd(app))
 	cmd.AddCommand(buildPaymentInteractiveCmd(app))
+	cmd.AddCommand(buildUpgradeCmd(app))
 	if app.Experimental {
 		cmd.AddCommand(buildInvoiceCmd(app))
 	}