add code preview

Cargo.lock

@@ -1018,9 +1018,9 @@ dependencies = [
 
 [[package]]
 name = "cc"
-version = "1.4.1"
+version = "1.2.67"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9066c49992464636f92905fa096ec58baaa4d57ec19a5c096c68d3e25ef3d136"
+checksum = "e17dd265a7d0f31ef544e1b20e03add05d3b45b491b633b10d67145d2acc1a38"
 dependencies = [
  "find-msvc-tools",
  "jobserver",
@@ -3522,6 +3522,41 @@ dependencies = [
  "smallvec",
  "smol",
  "tracing",
+ "tree-sitter",
+ "tree-sitter-astro-next",
+ "tree-sitter-bash",
+ "tree-sitter-c",
+ "tree-sitter-c-sharp",
+ "tree-sitter-cmake",
+ "tree-sitter-cpp",
+ "tree-sitter-css",
+ "tree-sitter-diff",
+ "tree-sitter-elixir",
+ "tree-sitter-embedded-template",
+ "tree-sitter-go",
+ "tree-sitter-graphql",
+ "tree-sitter-html",
+ "tree-sitter-java",
+ "tree-sitter-javascript",
+ "tree-sitter-jsdoc",
+ "tree-sitter-json",
+ "tree-sitter-kotlin-sg",
+ "tree-sitter-lua",
+ "tree-sitter-make",
+ "tree-sitter-md",
+ "tree-sitter-php",
+ "tree-sitter-proto",
+ "tree-sitter-python",
+ "tree-sitter-ruby",
+ "tree-sitter-rust",
+ "tree-sitter-scala",
+ "tree-sitter-sequel",
+ "tree-sitter-svelte-next",
+ "tree-sitter-swift",
+ "tree-sitter-toml-ng",
+ "tree-sitter-typescript",
+ "tree-sitter-yaml",
+ "tree-sitter-zig",
  "unicode-segmentation",
  "uuid",
  "windows 0.58.0",
@@ -8035,6 +8070,12 @@ version = "0.4.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d08889ec5408683408db66ad89e0e1f93dff55c73a4ccc71c427d5b277ee47e6"
 
+[[package]]
+name = "streaming-iterator"
+version = "0.1.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2b2231b7c3057d5e4ad0156fb3dc807d900806020c5ffa3ee6ff2c8c76fb8520"
+
 [[package]]
 name = "strict-num"
 version = "0.1.1"
@@ -8361,7 +8402,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "32497e9a4c7b38532efcdebeef879707aa9f794296a4f0244f6f69e9bc8574bd"
 dependencies = [
  "fastrand",
- "getrandom 0.4.3",
+ "getrandom 0.3.4",
  "once_cell",
  "rustix 1.1.4",
  "windows-sys 0.61.2",
@@ -8823,6 +8864,366 @@ dependencies = [
  "tracing-log",
 ]
 
+[[package]]
+name = "tree-sitter"
+version = "0.26.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "83c567a8e18ae93f20982c90370b16fd24023aeaf52f6052b96957ab253a0fec"
+dependencies = [
+ "cc",
+ "regex",
+ "regex-syntax",
+ "serde_json",
+ "streaming-iterator",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-astro-next"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "794a4a59fc2d88e49b4bc41fef9522d77184a36f4e68bbaf545cd1eb2364c46e"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-bash"
+version = "0.23.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "329a4d48623ac337d42b1df84e81a1c9dbb2946907c102ca72db158c1964a52e"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-c"
+version = "0.24.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a9b2eb57a55fed6b00812912e730b7a275cf4fe98bfd6a5d76263d4438371728"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-c-sharp"
+version = "0.23.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c1aac67f1ad71de1d6d39708d34811081c26dfa495658de6c14c34200849357c"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-cmake"
+version = "0.7.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "164e0c4f4236ec5ceff14824a5528615cf462e100467e49826442ff57d327061"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-cpp"
+version = "0.23.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "df2196ea9d47b4ab4a31b9297eaa5a5d19a0b121dceb9f118f6790ad0ab94743"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-css"
+version = "0.23.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5ad6489794d41350d12a7fbe520e5199f688618f43aace5443980d1ddcf1b29e"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-diff"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dfe1e5ca280a65dfe5ba4205c1bcc84edf486464fed315db53dee6da9a335889"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-elixir"
+version = "0.3.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "66dd064a762ed95bfc29857fa3cb7403bb1e5cb88112de0f6341b7e47284ba40"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-embedded-template"
+version = "0.23.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "790063ef14e5b67556abc0b3be0ed863fb41d65ee791cf8c0b20eb42a1fa46af"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-go"
+version = "0.23.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b13d476345220dbe600147dd444165c5791bf85ef53e28acbedd46112ee18431"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-graphql"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "efedc4cac157161cc23a0adc4553a2cedc908e1cd754b6cd033a919bb81ce5d6"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-html"
+version = "0.23.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "261b708e5d92061ede329babaaa427b819329a9d427a1d710abb0f67bbef63ee"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-java"
+version = "0.23.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0aa6cbcdc8c679b214e616fd3300da67da0e492e066df01bcf5a5921a71e90d6"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-javascript"
+version = "0.23.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bf40bf599e0416c16c125c3cec10ee5ddc7d1bb8b0c60fa5c4de249ad34dc1b1"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-jsdoc"
+version = "0.23.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a3862dfcb1038fc5e7812d7df14190afdeb7e1415288fd5f51f58395f8cb0faf"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-json"
+version = "0.24.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4d727acca406c0020cffc6cf35516764f36c8e3dc4408e5ebe2cb35a947ec471"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-kotlin-sg"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c06ec43ae3c12165d4ac08afe4e1f5fc6757ffe274fa7bd5af9007ef11ba4319"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-language"
+version = "0.1.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "009994f150cc0cd50ff54917d5bc8bffe8cad10ca10d81c34da2ec421ae61782"
+
+[[package]]
+name = "tree-sitter-lua"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ea992f4164d83f371ef1239ae178c4d4596c296c09055e9a48bb02a2760403af"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-make"
+version = "1.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c5998dc7cbcbdab19fae8aefef982bf2d6544513d8d2e69cc44aec4c63810104"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-md"
+version = "0.5.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2efd398be546456c814598ee56c0f51769a77241511b4a58077815d120afa882"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-php"
+version = "0.24.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0d8c17c3ab69052c5eeaa7ff5cd972dd1bc25d1b97ee779fec391ad3b5df5592"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-proto"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8e4360b434b5980fc397137ef29e1988619fef4159ac86fa7ac5777d459d3924"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-python"
+version = "0.23.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3d065aaa27f3aaceaf60c1f0e0ac09e1cb9eb8ed28e7bcdaa52129cffc7f4b04"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-ruby"
+version = "0.23.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "be0484ea4ef6bb9c575b4fdabde7e31340a8d2dbc7d52b321ac83da703249f95"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-rust"
+version = "0.24.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "439e577dbe07423ec2582ac62c7531120dbfccfa6e5f92406f93dd271a120e45"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-scala"
+version = "0.23.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "efde5e68b4736e9eac17bfa296c6f104a26bffab363b365eb898c40a63c15d2f"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-sequel"
+version = "0.3.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9d198ad3c319c02e43c21efa1ec796b837afcb96ffaef1a40c1978fbdcec7d17"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-svelte-next"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "56f88190d0743e897c3e148a7e241aba0a8844b8afe816943851426e3f7b9753"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-swift"
+version = "0.7.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fe36052155b9dd69ca82b3b8f1b4ccfb2d867125ac1a4db1dd7331829242668c"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-toml-ng"
+version = "0.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e9adc2c898ae49730e857d75be403da3f92bb81d8e37a2f918a08dd10de5ebb1"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-typescript"
+version = "0.23.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6c5f76ed8d947a75cc446d5fccd8b602ebf0cde64ccf2ffa434d873d7a575eff"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-yaml"
+version = "0.7.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "53c223db85f05e34794f065454843b0668ebc15d240ada63e2b5939f43ce7c97"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
+[[package]]
+name = "tree-sitter-zig"
+version = "1.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ab11fc124851b0db4dd5e55983bbd9631192e93238389dcd44521715e5d53e28"
+dependencies = [
+ "cc",
+ "tree-sitter-language",
+]
+
 [[package]]
 name = "triomphe"
 version = "0.1.16"

Cargo.toml

@@ -18,7 +18,9 @@ gpui_macos = { git = "https://github.com/zed-industries/zed" }
 gpui_tokio = { git = "https://github.com/zed-industries/zed" }
 reqwest_client = { git = "https://github.com/zed-industries/zed" }
 
-gpui-component = { git = "https://github.com/longbridge/gpui-component" }
+# `tree-sitter-languages` enables syntax highlighting for the TextView
+# code preview (fenced code blocks are highlighted with tree-sitter).
+gpui-component = { git = "https://github.com/longbridge/gpui-component", features = ["tree-sitter-languages"] }
 
 nostr = { git = "https://github.com/rust-nostr/nostr", features = ["nip59", "nip49", "nip44", "os-rng"] }
 nostr-lmdb = { git = "https://github.com/rust-nostr/nostr" }

crates/workspace/src/views/repo_detail/browser.rs

@@ -1,9 +1,10 @@
 //! File explorer of the repository detail view: the file tree column and the
-//! content column (README / file preview), backed by a persistent
+//! content column (README / file preview), backed by persistent
-//! [`TextViewState`] for markdown documents.
+//! [`TextViewState`]s for markdown documents and code files.
 
 use gpui::prelude::*;
 use gpui::{AnyElement, Context, Entity, SharedString, WeakEntity, div, px};
+use gpui_component::clipboard::Clipboard;
 use gpui_component::list::ListItem;
 use gpui_component::spinner::Spinner;
 use gpui_component::text::{TextView, TextViewState};
@@ -11,7 +12,7 @@ use gpui_component::tree::{TreeEntry, TreeState, tree};
 use gpui_component::{ActiveTheme, Icon, IconName, Sizable, StyledExt, h_flex, v_flex};
 
 use super::RepoDetailView;
-use super::helpers::{is_markdown_path, placeholder, plain_lines};
+use super::helpers::{code_language, fenced_code, is_markdown_path, placeholder};
 
 /// Width of the file explorer column.
 const TREE_WIDTH: f32 = 240.;
@@ -44,6 +45,28 @@ pub(super) struct MarkdownView {
     pub(super) state: Entity<TextViewState>,
 }
 
+/// A code file loaded into a persistent [`TextViewState`], rendered as a
+/// fenced code block so the markdown parser syntax-highlights it.
+///
+/// Same persistence rationale as [`MarkdownView`]: the state lives as long
+/// as this view, so re-viewing the same file does not re-parse it, and
+/// parsing happens on a background task.
+pub(super) struct CodeView {
+    /// Source path, relative to the worktree root.
+    pub(super) path: SharedString,
+    pub(super) state: Entity<TextViewState>,
+}
+
+/// Spinner shown while a document is being loaded/parsed.
+fn preview_spinner() -> AnyElement {
+    v_flex()
+        .size_full()
+        .items_center()
+        .justify_center()
+        .child(Spinner::new().small())
+        .into_any_element()
+}
+
 impl RepoDetailView {
     /// One row of the file tree: icon + name, indented by depth.
     fn render_tree_item(
@@ -150,14 +173,11 @@ impl RepoDetailView {
                 .into_any_element()
         } else if let Some(path) = selected_file {
             match self.files.get(path.as_ref()) {
-                Some(FileContent::Text(text)) => {
+                Some(FileContent::Text(_)) => {
                     if is_markdown_path(path.as_ref()) {
                         self.markdown_element(Some(path.as_ref()), cx)
                     } else {
-                        v_flex()
+                        self.code_element(path.as_ref(), cx)
-                            .size_full()
-                            .children(plain_lines(text, cx))
-                            .into_any_element()
                     }
                 }
                 Some(FileContent::Binary) => placeholder("Binary file — preview not supported", cx),
@@ -197,15 +217,7 @@ impl RepoDetailView {
                             .child(pane_title),
                     ),
             )
-            .child(
+            .child(div().id("repo-content").flex_1().min_h_0().child(body))
-                div()
-                    .id("repo-content-scroll")
-                    .flex_1()
-                    .min_h_0()
-                    .p_4()
-                    .overflow_y_scroll()
-                    .child(body),
-            )
     }
 
     /// Load `text` into the persistent markdown TextView state.
@@ -228,26 +240,71 @@ impl RepoDetailView {
     /// The persistent markdown TextView for `path` (`None` = README), or a
     /// spinner while the document is being loaded/parsed.
     fn markdown_element(&mut self, path: Option<&str>, _cx: &mut Context<Self>) -> AnyElement {
-        let spinner = || {
-            v_flex()
-                .size_full()
-                .items_center()
-                .justify_center()
-                .child(Spinner::new().small())
-                .into_any_element()
-        };
-
         let Some(md) = &self.md else {
-            return spinner();
+            return preview_spinner();
         };
         let ready = match path {
             Some(path) => md.path.as_deref() == Some(path),
             None => md.path.is_none(),
         };
         if !ready {
-            return spinner();
+            return preview_spinner();
         }
 
-        TextView::new(&md.state).selectable(true).into_any_element()
+        TextView::new(&md.state)
+            .selectable(true)
+            .scrollable(true)
+            .p_4()
+            .into_any_element()
+    }
+
+    /// Load `text` into the persistent code TextView state for `path`.
+    ///
+    /// The code is wrapped in a markdown fence (see [`fenced_code`]) so the
+    /// TextView renders it as a syntax-highlighted code block. Like
+    /// [`set_markdown`], the state is created empty and fed via `push_str`
+    /// so parsing happens on a background task instead of blocking the main
+    /// thread.
+    pub(super) fn set_code(&mut self, path: SharedString, text: &str, cx: &mut Context<Self>) {
+        let source = fenced_code(text, code_language(path.as_ref()));
+        let state = cx.new(|cx| TextViewState::markdown("", cx));
+        state.update(cx, |state, cx| state.push_str(&source, cx));
+        self.code = Some(CodeView { path, state });
+    }
+
+    /// The persistent code TextView for `path`, or a spinner while the file
+    /// is being loaded/parsed.
+    fn code_element(&mut self, path: &str, _cx: &mut Context<Self>) -> AnyElement {
+        let Some(code) = &self.code else {
+            return preview_spinner();
+        };
+        if code.path.as_ref() != path {
+            return preview_spinner();
+        }
+
+        TextView::new(&code.state)
+            .selectable(true)
+            .scrollable(true)
+            .p_4()
+            .code_block_actions(|code_block, _window, cx| {
+                let lang = code_block.lang().unwrap_or_default();
+                h_flex()
+                    .gap_2()
+                    .items_center()
+                    .when(!lang.is_empty(), |this| {
+                        this.child(
+                            div()
+                                .text_xs()
+                                .text_color(cx.theme().muted_foreground)
+                                .child(lang.clone()),
+                        )
+                    })
+                    .child(
+                        Clipboard::new(format!("copy-code-{lang}"))
+                            .value(code_block.code())
+                            .tooltip("Copy code"),
+                    )
+            })
+            .into_any_element()
     }
 }

crates/workspace/src/views/repo_detail/helpers.rs

@@ -1,5 +1,5 @@
-//! Pure helpers for the repository detail view: file-tree building, plain
+//! Pure helpers for the repository detail view: file-tree building, code
-//! text rendering and small element builders.
+//! preview helpers and small element builders.
 
 use std::path::{Path, PathBuf};
 
@@ -45,20 +45,85 @@ fn insert_path(items: &mut Vec<TreeItem>, parts: &[String], prefix: &str) {
     }
 }
 
-/// Render text with one element per line, preserving blank lines.
+/// The markdown fence language for a file path, or `None` for plain text.
-pub(super) fn plain_lines(text: &str, cx: &App) -> Vec<AnyElement> {
+///
-    text.lines()
+/// Names are chosen so `gpui_component`'s highlighter can resolve them
-        .map(|line| {
+/// (`highlighter::Language::from_name` accepts short aliases such as `rs`
-            // A space keeps empty lines from collapsing to zero height.
+/// and `js`).
-            let text = if line.is_empty() { " " } else { line };
+pub(super) fn code_language(path: &str) -> Option<&'static str> {
-            div()
+    let name = Path::new(path)
-                .font_family(cx.theme().mono_font_family.clone())
+        .file_name()
-                .text_xs()
+        .and_then(|name| name.to_str())
-                .text_color(cx.theme().foreground)
+        .unwrap_or_default();
-                .child(text.to_string())
+
-                .into_any_element()
+    // Some common files are recognized by name rather than extension.
-        })
+    match name {
-        .collect()
+        "Makefile" | "makefile" => return Some("make"),
+        "CMakeLists.txt" => return Some("cmake"),
+        _ => {}
+    }
+
+    let ext = Path::new(path).extension()?.to_str()?.to_ascii_lowercase();
+    Some(match ext.as_str() {
+        "rs" => "rust",
+        "toml" => "toml",
+        "json" | "jsonc" => "json",
+        "py" => "python",
+        "js" | "mjs" | "cjs" => "javascript",
+        "ts" | "mts" | "cts" => "typescript",
+        "tsx" | "jsx" => "tsx",
+        "go" => "go",
+        "c" | "h" => "c",
+        "cc" | "cpp" | "cxx" | "hh" | "hpp" | "hxx" => "cpp",
+        "cs" => "csharp",
+        "java" => "java",
+        "kt" | "kts" | "ktm" => "kotlin",
+        "swift" => "swift",
+        "php" | "phtml" => "php",
+        "rb" => "ruby",
+        "sh" | "bash" | "zsh" => "bash",
+        "yml" | "yaml" => "yaml",
+        "css" | "scss" | "sass" => "css",
+        "html" | "htm" => "html",
+        "lua" => "lua",
+        "sql" => "sql",
+        "proto" | "protobuf" => "proto",
+        "cmake" => "cmake",
+        "zig" => "zig",
+        "ex" | "exs" => "elixir",
+        "graphql" | "gql" => "graphql",
+        "diff" | "patch" => "diff",
+        "svelte" => "svelte",
+        "astro" => "astro",
+        "scala" => "scala",
+        _ => return None,
+    })
+}
+
+/// Wrap `code` in a fenced markdown code block tagged with `lang`, so the
+/// markdown [`TextViewState`] renders it as a syntax-highlighted code block.
+///
+/// The fence is one backtick longer than the longest run of backticks in
+/// `code`, so the content can never close the block early.
+pub(super) fn fenced_code(code: &str, lang: Option<&str>) -> String {
+    // Split on non-backtick characters so the segments are runs of backticks.
+    let longest_run = code.split(|c| c != '`').map(str::len).max().unwrap_or(0);
+    let fence = "`".repeat((longest_run + 1).max(3));
+
+    let mut out =
+        String::with_capacity(code.len() + fence.len() * 2 + lang.map_or(1, |lang| lang.len() + 2));
+    out.push_str(&fence);
+    if let Some(lang) = lang {
+        out.push(' ');
+        out.push_str(lang);
+    }
+    out.push('\n');
+    out.push_str(code);
+    if !code.ends_with('\n') {
+        out.push('\n');
+    }
+    out.push_str(&fence);
+    out
 }
 
 /// Whether a file path has a markdown extension.
@@ -134,4 +199,39 @@ mod tests {
         assert_eq!(items[0].children[0].id, "a/b");
         assert_eq!(items[0].children[0].children[0].id, "a/b/c.txt");
     }
+
+    #[test]
+    fn fenced_code_wraps_in_triple_backticks() {
+        let out = fenced_code("fn main() {}\n", Some("rust"));
+        assert_eq!(out, "``` rust\nfn main() {}\n```");
+    }
+
+    #[test]
+    fn fenced_code_uses_longer_fence_than_content() {
+        let code = "let x = \"```\";\n`code`";
+        let out = fenced_code(code, None);
+        // The longest run of backticks in `code` is 3, so the fence is 4.
+        assert!(out.starts_with("````\n"));
+        assert!(out.ends_with("````"));
+        assert!(out.contains(code));
+    }
+
+    #[test]
+    fn fenced_code_keeps_trailing_newline() {
+        assert_eq!(fenced_code("a\n", None), "```\na\n```");
+        assert_eq!(fenced_code("a", None), "```\na\n```");
+    }
+
+    #[test]
+    fn code_language_maps_extensions_and_names() {
+        assert_eq!(code_language("src/main.rs"), Some("rust"));
+        assert_eq!(code_language("Cargo.toml"), Some("toml"));
+        assert_eq!(code_language("app.js"), Some("javascript"));
+        assert_eq!(code_language("index.tsx"), Some("tsx"));
+        assert_eq!(code_language("Makefile"), Some("make"));
+        assert_eq!(code_language("CMakeLists.txt"), Some("cmake"));
+        assert_eq!(code_language("data.csv"), None);
+        assert_eq!(code_language("LICENSE"), None);
+        assert_eq!(code_language("README.md"), None);
+    }
 }

crates/workspace/src/views/repo_detail/mod.rs

@@ -18,7 +18,7 @@ use signed_state::{GitStore, RepoStore};
 mod browser;
 mod helpers;
 
-use browser::{FileContent, MAX_PREVIEW_BYTES, MarkdownView};
+use browser::{CodeView, FileContent, MAX_PREVIEW_BYTES, MarkdownView};
 use helpers::{build_tree_items, is_markdown_path};
 
 /// Detail view of a repository: header, stats, a file explorer with README
@@ -34,6 +34,8 @@ pub struct RepoDetailView {
     worktree: Option<PathBuf>,
     /// Markdown document currently in the preview pane (README or a file).
     md: Option<MarkdownView>,
+    /// Code file currently in the preview pane.
+    code: Option<CodeView>,
     readme_name: Option<SharedString>,
     /// Currently previewed file (relative path) and its contents.
     selected_file: Option<SharedString>,
@@ -63,6 +65,7 @@ impl RepoDetailView {
             tree_state,
             worktree: None,
             md: None,
+            code: None,
             readme_name: None,
             selected_file: None,
             files: HashMap::new(),
@@ -150,9 +153,11 @@ impl RepoDetailView {
                     Component::ParentDir | Component::RootDir | Component::Prefix(_)
                 )
             });
+
         let Some(worktree) = self.worktree.clone() else {
             return;
         };
+
         if unsafe_path {
             return;
         }
@@ -186,13 +191,19 @@ impl RepoDetailView {
                 this.loading_files.remove(&path);
                 match content {
                     Ok(kind) => {
-                        if let FileContent::Text(text) = &kind
+                        if let FileContent::Text(text) = &kind {
-                            && is_markdown_path(&path)
+                            if is_markdown_path(&path) {
-                        {
+                                let same = this.md.as_ref().map(|md| md.path.as_deref())
-                            let same = this.md.as_ref().map(|md| md.path.as_deref())
+                                    == Some(Some(path.as_str()));
-                                == Some(Some(path.as_str()));
+                                if !same {
-                            if !same {
+                                    this.set_markdown(Some(path.clone().into()), text, cx);
-                                this.set_markdown(Some(path.clone().into()), text, cx);
+                                }
+                            } else {
+                                let same = this.code.as_ref().map(|code| code.path.as_str())
+                                    == Some(path.as_str());
+                                if !same {
+                                    this.set_code(path.clone().into(), text, cx);
+                                }
                             }
                         }
                         this.files.insert(path, kind);
@@ -280,6 +291,7 @@ impl Render for RepoDetailView {
                     .pt_2()
                     .pb_4()
                     .w_full()
+                    .items_start()
                     .justify_between()
                     .border_b_1()
                     .border_color(cx.theme().border)