From bf11fd7fd9abba16c0faaf10b2e9636760f7c4d6 Mon Sep 17 00:00:00 2001
From: Simon Klee <hello@simonklee.dk>
Date: Sat, 7 Nov 2026 03:48:51 +0100
Subject: [PATCH] perf(cli-rs): build url without ICU by pinning idna_adapter
 1.0.0

The idna_adapter 1.0.0 stub turns IDNA off in url, which drops ICU4X: 21 crates, 2 build scripts and 4 proc macros. A non-ASCII host now fails to parse; punycode hosts still work. The client names the cause when a base URL such as --server has one (deviation A10-ascii-hosts, decision E1).
---
 packages/cli-rs/Cargo.lock                    | 228 +-----------------
 packages/cli-rs/Cargo.toml                    |   3 +
 packages/cli-rs/crates/api/Cargo.toml         |   1 +
 packages/cli-rs/crates/api/src/client.rs      |   9 +-
 packages/cli-rs/crates/api/tests/api.rs       |  16 ++
 .../parity/deviations/A10-ascii-hosts.md      |  21 ++
 6 files changed, 51 insertions(+), 227 deletions(-)
 create mode 100644 packages/cli-rs/parity/deviations/A10-ascii-hosts.md

diff --git a/packages/cli-rs/Cargo.lock b/packages/cli-rs/Cargo.lock
index 8edd17976b1..5979eba155c 100644
--- a/packages/cli-rs/Cargo.lock
+++ b/packages/cli-rs/Cargo.lock
@@ -292,17 +292,6 @@ dependencies = [
  "crypto-common",
 ]
 
-[[package]]
-name = "displaydoc"
-version = "0.2.7"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c6232dd377dcc64799954cbd3a9bb882e9cdc1308ccd87b1c098f1fb2eaf82a8"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn 3.0.9",
-]
-
 [[package]]
 name = "equivalent"
 version = "1.0.3"
@@ -577,89 +566,6 @@ dependencies = [
  "cc",
 ]
 
-[[package]]
-name = "icu_collections"
-version = "2.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fe090a42a0d3140fed8c63263ed1fecc02422cb2f4bfe55cd8de2de1b8e105dd"
-dependencies = [
- "displaydoc",
- "potential_utf",
- "utf8_iter",
- "yoke",
- "zerofrom",
- "zerovec",
-]
-
-[[package]]
-name = "icu_locale_core"
-version = "2.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "25d29b57c17c6528d0dc4c2141cfa2d08200465acb537a3909c8b9b8a4a984c0"
-dependencies = [
- "displaydoc",
- "litemap",
- "tinystr",
- "writeable",
- "zerovec",
-]
-
-[[package]]
-name = "icu_normalizer"
-version = "2.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "404a3b8c486f205c87fe7f23ab6894d84a4ad76d6e4671ae1981ba7def87c599"
-dependencies = [
- "icu_collections",
- "icu_normalizer_data",
- "icu_properties",
- "icu_provider",
- "smallvec",
- "zerovec",
-]
-
-[[package]]
-name = "icu_normalizer_data"
-version = "2.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "20f0088bfb7441f7a37fa0c9e20cb1e9cba1cac6b9ce8cd2a6dc44294f8e8cbc"
-
-[[package]]
-name = "icu_properties"
-version = "2.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2ea83d991c56158f7cf898bf86436c1dfe7c07ee82fe88951f2695c9f37a379f"
-dependencies = [
- "displaydoc",
- "icu_collections",
- "icu_locale_core",
- "icu_properties_data",
- "icu_provider",
- "zerotrie",
- "zerovec",
-]
-
-[[package]]
-name = "icu_properties_data"
-version = "2.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b98f29af82d02b163fe50161388350e743bb3107cc8e8c2f7314cb505faddfcf"
-
-[[package]]
-name = "icu_provider"
-version = "2.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "413099315636c588ee8f011190b329b971a09a8fae9d157e01dcae8379468514"
-dependencies = [
- "displaydoc",
- "icu_locale_core",
- "writeable",
- "yoke",
- "zerofrom",
- "zerotrie",
- "zerovec",
-]
-
 [[package]]
 name = "idna"
 version = "1.1.0"
@@ -673,13 +579,9 @@ dependencies = [
 
 [[package]]
 name = "idna_adapter"
-version = "1.2.2"
+version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cb68373c0d6620ef8105e855e7745e18b0d00d3bdb07fb532e434244cdb9a714"
-dependencies = [
- "icu_normalizer",
- "icu_properties",
-]
+checksum = "cfdf4f5d937a025381f5ab13624b1c5f51414bfe5c9885663226eae8d6d39560"
 
 [[package]]
 name = "indexmap"
@@ -833,12 +735,6 @@ version = "0.12.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "32a66949e030da00e8c7d4434b251670a91556f4144941d37452769c25d58a53"
 
-[[package]]
-name = "litemap"
-version = "0.8.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "47d9d19d1d6efa0109d2f65ff4c85cddd50bd572e5a00127ab10987290bcefae"
-
 [[package]]
 name = "log"
 version = "0.4.35"
@@ -961,6 +857,7 @@ dependencies = [
  "base64",
  "bytes",
  "futures-util",
+ "idna_adapter",
  "indexmap",
  "log",
  "memchr",
@@ -1302,15 +1199,6 @@ version = "0.2.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a89322df9ebe1c1578d689c92318e070967d1042b512afbe49518723f4e6d5cd"
 
-[[package]]
-name = "potential_utf"
-version = "0.1.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d83eb9bc6d8e5cf568e7a1101d60ee05e81ed50ea106026f3d18deeb046d7661"
-dependencies = [
- "zerovec",
-]
-
 [[package]]
 name = "proc-macro2"
 version = "1.0.107"
@@ -1712,12 +1600,6 @@ dependencies = [
  "windows-sys 0.61.2",
 ]
 
-[[package]]
-name = "stable_deref_trait"
-version = "1.2.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6ce2be8dc25455e1f91df71bfa12ad37d7af1092ae736f3a6cd0e37bc7810596"
-
 [[package]]
 name = "streaming-iterator"
 version = "0.1.9"
@@ -1767,17 +1649,6 @@ dependencies = [
  "futures-core",
 ]
 
-[[package]]
-name = "synstructure"
-version = "0.14.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "901704edd0dfe137f1987838ee4f259e4e063c31371bdb423f7ae38ec6f77f02"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn 3.0.9",
-]
-
 [[package]]
 name = "tempfile"
 version = "3.27.0"
@@ -1821,16 +1692,6 @@ dependencies = [
  "syn 3.0.9",
 ]
 
-[[package]]
-name = "tinystr"
-version = "0.8.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "abc840c238154d58f9e86b2792261edfde565a17696e1cda1a449de27979801a"
-dependencies = [
- "displaydoc",
- "zerovec",
-]
-
 [[package]]
 name = "tokio"
 version = "1.54.1"
@@ -2688,95 +2549,12 @@ version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"
 
-[[package]]
-name = "writeable"
-version = "0.6.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3ad82d2a33cdc9674dc7465672f271e096168fcdbe0f799d9e6db8c5892679dc"
-
-[[package]]
-name = "yoke"
-version = "0.8.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "417ef3fcf6c300b7dbd25c85531a746931c02ad536f3cf4786ed1e88223340b3"
-dependencies = [
- "stable_deref_trait",
- "yoke-derive",
- "zerofrom",
-]
-
-[[package]]
-name = "yoke-derive"
-version = "0.8.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ec8ebde2db3681e8c9980cc27822030e68752690ddfa9473e739aeb4dbde6d71"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn 3.0.9",
- "synstructure",
-]
-
-[[package]]
-name = "zerofrom"
-version = "0.1.8"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0ec05a11813ea801ff6d75110ad09cd0824ddba17dfe17128ea0d5f68e6c5272"
-dependencies = [
- "zerofrom-derive",
-]
-
-[[package]]
-name = "zerofrom-derive"
-version = "0.1.8"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f75b4683f6c7f45248d4d64056a24298c6281e0993356d7d1b4a1a962ef10d4a"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn 3.0.9",
- "synstructure",
-]
-
 [[package]]
 name = "zeroize"
 version = "1.9.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e13084392c5e4bc371903e2935a5eaeed24905a7511356b883835e18a78f6879"
 
-[[package]]
-name = "zerotrie"
-version = "0.2.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4ea269c3bd32f0a32c321907a2ae912ba6f4649bb0fc764a15627e99a7095a3f"
-dependencies = [
- "displaydoc",
- "yoke",
- "zerofrom",
-]
-
-[[package]]
-name = "zerovec"
-version = "0.11.9"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f58a2799cfe9a1670c7ea8edbd52ef8edb93cb37a7f83bf31ba9e35d9dae6a40"
-dependencies = [
- "yoke",
- "zerofrom",
- "zerovec-derive",
-]
-
-[[package]]
-name = "zerovec-derive"
-version = "0.11.7"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c3743ddbf47738d929cd1ae2e199d40d0162979dfe31aef8ae646d2bf00bf97a"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn 3.0.9",
-]
-
 [[package]]
 name = "zmij"
 version = "1.0.23"
diff --git a/packages/cli-rs/Cargo.toml b/packages/cli-rs/Cargo.toml
index ebf326e766b..256188c9b10 100644
--- a/packages/cli-rs/Cargo.toml
+++ b/packages/cli-rs/Cargo.toml
@@ -40,6 +40,9 @@ chrono = { version = "0.4", default-features = false, features = ["std", "clock"
 clap = { version = "4", features = ["derive", "wrap_help"] }
 clap_complete = "4"
 futures-util = { version = "0.3", default-features = false, features = ["std", "sink"] }
+# The IDNA stub: `url` rejects non-ASCII hosts instead of pulling ICU4X (deviation A10-ascii-hosts). Pinned so a
+# `cargo update` cannot bring 1.2 back.
+idna_adapter = "=1.0.0"
 indexmap = { version = "2", features = ["serde"] }
 libloading = "0.9"
 log = { version = "0.4", features = ["std"] }
diff --git a/packages/cli-rs/crates/api/Cargo.toml b/packages/cli-rs/crates/api/Cargo.toml
index 3b62cdc5a50..12a2cea5ae9 100644
--- a/packages/cli-rs/crates/api/Cargo.toml
+++ b/packages/cli-rs/crates/api/Cargo.toml
@@ -14,6 +14,7 @@ opencode-api-types.workspace = true
 base64.workspace = true
 bytes.workspace = true
 futures-util.workspace = true
+idna_adapter.workspace = true
 log.workspace = true
 memchr.workspace = true
 percent-encoding.workspace = true
diff --git a/packages/cli-rs/crates/api/src/client.rs b/packages/cli-rs/crates/api/src/client.rs
index 0f2dd49b481..81e760a3989 100644
--- a/packages/cli-rs/crates/api/src/client.rs
+++ b/packages/cli-rs/crates/api/src/client.rs
@@ -77,8 +77,13 @@ impl Client {
     }
 
     pub fn with_transport(base_url: &str, transport: Arc<dyn Transport>) -> Result<Self, Error> {
-        let mut base_url =
-            url::Url::parse(base_url).map_err(|error| Error::Transport(format!("{base_url}: {error}")))?;
+        let mut base_url = url::Url::parse(base_url).map_err(|error| match error {
+            // `url` is built without IDNA (deviation A10-ascii-hosts).
+            url::ParseError::IdnaError => Error::Transport(format!(
+                "{base_url}: a host name must be ASCII; write an international name in its punycode (xn--) form"
+            )),
+            error => Error::Transport(format!("{base_url}: {error}")),
+        })?;
         // A leading slash would replace any path prefix on the base URL, so paths join relative to it.
         if !base_url.path().ends_with('/') {
             let path = format!("{}/", base_url.path());
diff --git a/packages/cli-rs/crates/api/tests/api.rs b/packages/cli-rs/crates/api/tests/api.rs
index 03672360374..a8b73ea3f90 100644
--- a/packages/cli-rs/crates/api/tests/api.rs
+++ b/packages/cli-rs/crates/api/tests/api.rs
@@ -44,6 +44,22 @@ fn client(script: &Arc<Script>) -> Client {
     Client::with_transport("http://127.0.0.1:4096", script.clone()).unwrap()
 }
 
+#[test]
+fn hosts_must_be_ascii_or_punycode() {
+    let script = Script::new(200, "application/json", "{}");
+    for url in ["https://example.com", "https://xn--bcher-kva.example"] {
+        let client = Client::with_transport(url, script.clone()).unwrap();
+        assert_eq!(client.base_url().as_str(), format!("{url}/"));
+    }
+    let Err(Error::Transport(message)) = Client::with_transport("https://bücher.example", script) else {
+        panic!("a Unicode host parsed");
+    };
+    assert_eq!(
+        message,
+        "https://bücher.example: a host name must be ASCII; write an international name in its punycode (xn--) form"
+    );
+}
+
 #[test]
 fn tagged_union_decodes_known_rpc_and_unknown_members() {
     let connected: V2Event =
diff --git a/packages/cli-rs/parity/deviations/A10-ascii-hosts.md b/packages/cli-rs/parity/deviations/A10-ascii-hosts.md
new file mode 100644
index 00000000000..20c84ddc10c
--- /dev/null
+++ b/packages/cli-rs/parity/deviations/A10-ascii-hosts.md
@@ -0,0 +1,21 @@
+# A10: URL hosts must be ASCII
+
+TypeScript: `new URL` follows the WHATWG URL standard, which maps an international host name to
+its punycode form with UTS 46. `https://bücher.example` parses as `https://xn--bcher-kva.example/`.
+
+Rust: the `url` crate is built with the `idna_adapter` 1.0.0 stub (pinned in the root
+`Cargo.toml`, used by `crates/api`), which turns IDNA off. A host with a non-ASCII character fails
+to parse. A punycode host (`https://xn--bcher-kva.example`) and every ASCII host parse as before.
+
+Where a user can type such a URL, the failure is reported:
+
+- `--server` and any other base URL given to `opencode_api::Client`: "<url>: a host name must be
+  ASCII; write an international name in its punycode (xn--) form".
+- MCP and form URL fields (`format: uri`): "Expected a URL", as for any URL that does not parse.
+- Opening a link: "Only http and https links can be opened in the browser: <url>".
+
+The stub also stops `url` from checking UTS 46 rules on punycode labels, so a malformed `xn--`
+label parses where TypeScript rejects it; the server or DNS rejects it later.
+
+Reason: decision O-58 (E1). Full IDNA pulls ICU4X into the build, 21 crates with 2 build scripts
+and 4 proc macros, for host names that a user can write in punycode.