feat: ultra polish package manager (#13573)

See the readme

codex-rs/package-manager/src/error.rs

@@ -0,0 +1,54 @@
+use std::path::PathBuf;
+use thiserror::Error;
+
+/// Errors returned by the generic package manager.
+#[derive(Debug, Error)]
+pub enum PackageManagerError {
+    /// The current machine OS/architecture pair is not supported by the package.
+    #[error("unsupported platform: {os}-{arch}")]
+    UnsupportedPlatform { os: String, arch: String },
+
+    /// The configured release base URL could not be joined with a package-specific path.
+    #[error("invalid release base url")]
+    InvalidBaseUrl(#[source] url::ParseError),
+
+    /// An HTTP request failed while fetching the manifest or archive.
+    #[error("{context}")]
+    Http {
+        context: String,
+        #[source]
+        source: reqwest::Error,
+    },
+
+    /// A filesystem operation failed while reading, staging, or promoting a package.
+    #[error("{context}")]
+    Io {
+        context: String,
+        #[source]
+        source: std::io::Error,
+    },
+
+    /// The release manifest did not contain an archive for the current platform.
+    #[error("missing platform entry `{0}` in release manifest")]
+    MissingPlatform(String),
+
+    /// The release manifest or installed package reported a different version than requested.
+    #[error("unexpected package version: expected `{expected}`, got `{actual}`")]
+    UnexpectedPackageVersion { expected: String, actual: String },
+
+    /// The downloaded archive length did not match the manifest metadata.
+    #[error("unexpected archive size: expected `{expected}`, got `{actual}`")]
+    UnexpectedArchiveSize { expected: u64, actual: u64 },
+
+    /// The downloaded archive checksum did not match the manifest metadata.
+    #[error("checksum mismatch: expected `{expected}`, got `{actual}`")]
+    ChecksumMismatch { expected: String, actual: String },
+
+    /// Archive extraction failed or the archive contents violated extraction rules.
+    #[error("archive extraction failed: {0}")]
+    ArchiveExtraction(String),
+
+    /// The extracted archive layout did not contain a detectable package root.
+    #[error("archive did not contain a package root with manifest.json under {0}")]
+    MissingPackageRoot(PathBuf),
+}