diff --git a/Cargo.lock b/Cargo.lock
index 8ad9039..6ba8eef 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -10,9 +10,9 @@ checksum = "320119579fcad9c21884f5c4861d16174d0e06250625266f50fe6898340abefa"
 
 [[package]]
 name = "anyhow"
-version = "1.0.102"
+version = "1.0.97"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7f202df86484c868dbad7eaa557ef785d5c66295e41b460ef922eca0723b842c"
+checksum = "dcfed56ad506cb2c684a14971b8861fdc3baaaae314b9e5f9bb532cbe3ba7a4f"
 
 [[package]]
 name = "auditable-serde"
@@ -28,9 +28,9 @@ dependencies = [
 
 [[package]]
 name = "bitflags"
-version = "2.11.1"
+version = "2.9.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c4512299f36f043ab09a583e57bceb5a5aab7a73db1805848e8fef3c9e8c78b3"
+checksum = "5c8214115b7bf84099f1309324e63141d4c5d7cc26862f97a0a857dbefe165bd"
 
 [[package]]
 name = "cfg-if"
@@ -179,19 +179,13 @@ dependencies = [
 
 [[package]]
 name = "hashbrown"
-version = "0.15.5"
+version = "0.15.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9229cfe53dfd69f0609a49f65461bd93001ea1ef889cd5529dd176593f5338a1"
+checksum = "bf151400ff0baff5465007dd2f3e717f3fe502074ca563069ce3a6629d07b289"
 dependencies = [
  "foldhash",
 ]
 
-[[package]]
-name = "hashbrown"
-version = "0.17.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ed5909b6e89a2db4456e54cd5f673791d7eca6732202bbf2a9cc504fe2f9b84a"
-
 [[package]]
 name = "heck"
 version = "0.5.0"
@@ -282,9 +276,9 @@ dependencies = [
 
 [[package]]
 name = "id-arena"
-version = "2.3.0"
+version = "2.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3d3067d79b975e8844ca9eb072e16b31c3c1c36928edf9c6789548c524d0d954"
+checksum = "25a2bc672d1148e28034f176e01fffebb08b35768468cc954630da77a1449005"
 
 [[package]]
 name = "idna"
@@ -309,21 +303,20 @@ dependencies = [
 
 [[package]]
 name = "indexmap"
-version = "2.14.0"
+version = "2.7.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d466e9454f08e4a911e14806c24e16fba1b4c121d1ea474396f396069cf949d9"
+checksum = "8c9c992b02b5b4c94ea26e32fe5bccb7aa7d9f390ab5c1221ff895bc7ea8b652"
 dependencies = [
  "equivalent",
- "hashbrown 0.17.1",
+ "hashbrown",
  "serde",
- "serde_core",
 ]
 
 [[package]]
 name = "itoa"
-version = "1.0.18"
+version = "1.0.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8f42a60cbdf9a97f5d2305f08a87dc4e09308d1276d28c869c684d7777685682"
+checksum = "4a5f13b858c8d314ee3e8f639011f7ccefe71f97f96e50151fb991f267928e2c"
 
 [[package]]
 name = "leb128fmt"
@@ -339,15 +332,15 @@ checksum = "92daf443525c4cce67b150400bc2316076100ce0b3686209eb8cf3c31612e6f0"
 
 [[package]]
 name = "log"
-version = "0.4.29"
+version = "0.4.26"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5e5032e24019045c762d3c0f28f5b6b8bbf38563a65908389bf7978758920897"
+checksum = "30bde2b3dc3671ae49d8e2e9f044c7c005836e7a023ee57cffa25ab82764bb9e"
 
 [[package]]
 name = "memchr"
-version = "2.8.0"
+version = "2.7.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f8ca58f447f06ed17d5fc4043ce1b10dd205e060fb3ce5b979b8ed8e59ff3f79"
+checksum = "78ca9ab1a0babb1e7d5695e3530886289c18cf2f87ec19a575a0abdce112e3a3"
 
 [[package]]
 name = "miniz_oxide"
@@ -398,30 +391,29 @@ dependencies = [
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.106"
+version = "1.0.94"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8fd00f0bb2e90d81d1044c2b32617f68fcb9fa3bb7640c23e9c748e53fb30934"
+checksum = "a31971752e70b8b2686d7e46ec17fb38dad4051d94024c88df49b667caea9c84"
 dependencies = [
  "unicode-ident",
 ]
 
 [[package]]
 name = "quote"
-version = "1.0.45"
+version = "1.0.46"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "41f2619966050689382d2b44f664f4bc593e129785a36d6ee376ddf37259b924"
+checksum = "dfbc457d0c7a0759a614551b11a6409e5951f6c7537be1f1b7682b9ae9230368"
 dependencies = [
  "proc-macro2",
 ]
 
 [[package]]
 name = "semver"
-version = "1.0.28"
+version = "1.0.26"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8a7852d02fc848982e0c167ef163aaff9cd91dc640ba85e263cb1ce46fae51cd"
+checksum = "56e6fa9c48d24d85fb3de5ad847117517440f6beceb7798af16b4a87d616b8d0"
 dependencies = [
  "serde",
- "serde_core",
 ]
 
 [[package]]
@@ -456,9 +448,9 @@ dependencies = [
 
 [[package]]
 name = "serde_json"
-version = "1.0.149"
+version = "1.0.150"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "83fc039473c5595ace860d8c4fafa220ff474b3fc6bfdb4293327f1a37e94d86"
+checksum = "e8014e44b4736ed0538adeecded0fce2a272f22dc9578a7eb6b2d9993c74cfb9"
 dependencies = [
  "itoa",
  "memchr",
@@ -481,15 +473,15 @@ checksum = "0c790de23124f9ab44544d7ac05d60440adc586479ce501c1d6d7da3cd8c9cf5"
 
 [[package]]
 name = "smallvec"
-version = "1.15.1"
+version = "1.14.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "67b1b7a3b5fe4f1376887184045fcf45c69e92af734b7aaddc05fb777b6fbd03"
+checksum = "7fcf8323ef1faaee30a44a340193b1ac6814fd9b7b4e88e9d4519a3e4abe1cfd"
 
 [[package]]
 name = "spdx"
-version = "0.10.9"
+version = "0.10.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c3e17e880bafaeb362a7b751ec46bdc5b61445a188f80e0606e68167cd540fa3"
+checksum = "58b69356da67e2fc1f542c71ea7e654a361a79c938e4424392ecf4fa065d2193"
 dependencies = [
  "smallvec",
 ]
@@ -540,9 +532,9 @@ checksum = "ea68304e134ecd095ac6c3574494fc62b909f416c4fca77e440530221e549d3d"
 
 [[package]]
 name = "unicode-ident"
-version = "1.0.24"
+version = "1.0.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e6e4313cd5fcd3dad5cafa179702e2b244f760991f45397d14d4ebf38247da75"
+checksum = "5a5f39404a5da50712a4c1eecf25e90dd62b613502b7e925fd4e4d19b5c96512"
 
 [[package]]
 name = "unicode-xid"
@@ -604,7 +596,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0f51cad774fb3c9461ab9bccc9c62dfb7388397b5deda31bf40e8108ccd678b2"
 dependencies = [
  "bitflags",
- "hashbrown 0.15.5",
+ "hashbrown",
  "indexmap",
  "semver",
 ]
@@ -753,6 +745,7 @@ dependencies = [
 name = "zed_haskell"
 version = "0.3.2"
 dependencies = [
+ "serde_json",
  "zed_extension_api",
 ]
 
diff --git a/Cargo.toml b/Cargo.toml
index 2b4f363..8cddda7 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -11,3 +11,6 @@ crate-type = ["cdylib"]
 
 [dependencies]
 zed_extension_api = "0.7.0"
+
+[dev-dependencies]
+serde_json = "1.0.150"
diff --git a/languages/haskell/runnables.scm b/languages/haskell/runnables.scm
new file mode 100644
index 0000000..7b9959d
--- /dev/null
+++ b/languages/haskell/runnables.scm
@@ -0,0 +1,11 @@
+; Detect the main function
+(declarations
+  [
+    (function
+      name: (variable) @run)
+    (bind
+      name: (variable) @run)
+  ]
+  (#eq? @run "main")
+  (#set! tag haskell-build)
+  (#set! tag haskell-run))
diff --git a/languages/haskell/tasks.json b/languages/haskell/tasks.json
new file mode 100644
index 0000000..58d86e7
--- /dev/null
+++ b/languages/haskell/tasks.json
@@ -0,0 +1,26 @@
+[
+  {
+    "label": "Run",
+    "command": "if [ -f stack.yaml ]; then stack run; elif [ -f cabal.project ] || ls *.cabal 2>/dev/null | grep -q .; then cabal run; else echo 'No Stack or Cabal found to run the code' >&2; exit 1; fi",
+    "tags": ["haskell-run"],
+    "shell": {
+      "with_arguments": {
+        "program": "/bin/sh",
+        "args": ["-c"]
+      }
+    },
+    "show_command": false
+  },
+  {
+    "label": "Build",
+    "command": "if [ -f stack.yaml ]; then stack build; elif [ -f cabal.project ] || ls *.cabal 2>/dev/null | grep -q .; then cabal build; else echo 'No Stack or Cabal found to build the code' >&2; exit 1; fi",
+    "tags": ["haskell-build"],
+    "shell": {
+      "with_arguments": {
+        "program": "/bin/sh",
+        "args": ["-c"]
+      }
+    },
+    "show_command": false
+  }
+]
diff --git a/tests/task_verification_test.rs b/tests/task_verification_test.rs
new file mode 100644
index 0000000..c62815e
--- /dev/null
+++ b/tests/task_verification_test.rs
@@ -0,0 +1,169 @@
+// Heavily inspired by the Java extension's task verification tests:
+// https://github.com/zed-extensions/java/blob/b6b8f9a5396b7f794d12a91ee4c703078ecc3e96/tests/task_verification_test.rs
+
+use serde_json::Value;
+use std::fs;
+use std::path::PathBuf;
+use std::process::Command;
+
+fn get_task_command_by_tag(tag: &str) -> String {
+    let tasks_json =
+        fs::read_to_string("languages/haskell/tasks.json").expect("Failed to read tasks.json");
+    let tasks: Value = serde_json::from_str(&tasks_json).expect("Failed to parse tasks.json");
+    for task in tasks.as_array().expect("tasks.json is not an array") {
+        if let Some(tags) = task["tags"].as_array() {
+            if tags.iter().any(|t| t.as_str() == Some(tag)) {
+                return task["command"]
+                    .as_str()
+                    .expect("command is not a string")
+                    .to_string();
+            }
+        }
+    }
+    panic!("Task with tag '{tag}' not found");
+}
+
+struct TestProject {
+    temp_dir: PathBuf,
+    bin_dir: PathBuf,
+    new_path: String,
+}
+
+impl TestProject {
+    fn new(name: &str) -> Self {
+        let temp_dir = std::env::temp_dir().join(format!("haskell_task_test_{name}"));
+        if temp_dir.exists() {
+            fs::remove_dir_all(&temp_dir).unwrap();
+        }
+        fs::create_dir_all(&temp_dir).unwrap();
+        let bin_dir = temp_dir.join("bin");
+        fs::create_dir_all(&bin_dir).unwrap();
+        let new_path = format!(
+            "{}:{}",
+            bin_dir.to_string_lossy(),
+            std::env::var("PATH").unwrap_or_default()
+        );
+        Self {
+            temp_dir,
+            bin_dir,
+            new_path,
+        }
+    }
+
+    fn with_stack(&self) {
+        fs::File::create(self.temp_dir.join("stack.yaml")).unwrap();
+        fs::File::create(self.temp_dir.join("myproject.cabal")).unwrap();
+        self.mock_bin("stack", "#!/bin/sh\necho \"STACK_CALLED: $@\"");
+    }
+
+    fn with_cabal(&self) {
+        fs::File::create(self.temp_dir.join("myproject.cabal")).unwrap();
+        self.mock_bin("cabal", "#!/bin/sh\necho \"CABAL_CALLED: $@\"");
+    }
+
+    fn with_cabal_project(&self) {
+        fs::File::create(self.temp_dir.join("cabal.project")).unwrap();
+        self.mock_bin("cabal", "#!/bin/sh\necho \"CABAL_CALLED: $@\"");
+    }
+
+    fn mock_bin(&self, name: &str, content: &str) {
+        let bin_path = self.bin_dir.join(name);
+        fs::write(&bin_path, content).unwrap();
+        #[cfg(unix)]
+        {
+            use std::os::unix::fs::PermissionsExt;
+            fs::set_permissions(&bin_path, fs::Permissions::from_mode(0o755)).unwrap();
+        }
+    }
+
+    fn run_task(&self, tag: &str) -> String {
+        let command = get_task_command_by_tag(tag);
+        let output = Command::new("sh")
+            .arg("-c")
+            .arg(&command)
+            .env("PATH", &self.new_path)
+            .current_dir(&self.temp_dir)
+            .output()
+            .expect("Failed to execute shell command");
+        String::from_utf8_lossy(&output.stdout).into_owned()
+            + &String::from_utf8_lossy(&output.stderr)
+    }
+}
+
+impl Drop for TestProject {
+    fn drop(&mut self) {
+        let _ = fs::remove_dir_all(&self.temp_dir);
+    }
+}
+
+#[test]
+fn test_stack_build() {
+    let project = TestProject::new("stack_build");
+    project.with_stack();
+    let output = project.run_task("haskell-build");
+    assert!(output.contains("STACK_CALLED: build"), "Got: {}", output);
+}
+
+#[test]
+fn test_stack_run() {
+    let project = TestProject::new("stack_run");
+    project.with_stack();
+    let output = project.run_task("haskell-run");
+    assert!(output.contains("STACK_CALLED: run"), "Got: {}", output);
+}
+
+#[test]
+fn test_cabal_build() {
+    let project = TestProject::new("cabal_build");
+    project.with_cabal();
+    let output = project.run_task("haskell-build");
+    assert!(output.contains("CABAL_CALLED: build"), "Got: {}", output);
+}
+
+#[test]
+fn test_cabal_run() {
+    let project = TestProject::new("cabal_run");
+    project.with_cabal();
+    let output = project.run_task("haskell-run");
+    assert!(output.contains("CABAL_CALLED: run"), "Got: {}", output);
+}
+
+#[test]
+fn test_cabal_project_build() {
+    let project = TestProject::new("cabal_project_build");
+    project.with_cabal_project();
+    let output = project.run_task("haskell-build");
+    assert!(output.contains("CABAL_CALLED: build"), "Got: {}", output);
+}
+
+#[test]
+fn test_cabal_project_run() {
+    let project = TestProject::new("cabal_project_run");
+    project.with_cabal_project();
+    let output = project.run_task("haskell-run");
+    assert!(output.contains("CABAL_CALLED: run"), "Got: {}", output);
+}
+
+#[test]
+fn test_stack_preferred_over_cabal() {
+    let project = TestProject::new("stack_preferred");
+    project.with_stack();
+    project.with_cabal();
+    let output = project.run_task("haskell-run");
+    assert!(
+        output.contains("STACK_CALLED: run"),
+        "Stack should be preferred when stack.yaml present. Got: {}",
+        output
+    );
+}
+
+#[test]
+fn test_no_build_tool() {
+    let project = TestProject::new("no_tool");
+    let output = project.run_task("haskell-build");
+    assert!(
+        output.contains("No Stack or Cabal found"),
+        "Got: {}",
+        output
+    );
+}