feat(lang): rename schedule keyword from extends to modifies

Changed the schedule composition keyword from "extends" to "modifies"
to better reflect the semantic meaning of schedule inheritance. When
a schedule modifies another, it inherits base blocks and can override
them by name or add new blocks.

This is a breaking change for all existing Storybook files that use
schedule composition. The migration is a simple find-and-replace:
  schedule X extends Y → schedule X modifies Y

Changes include:
- Grammar: Updated tree-sitter grammar and lexer token
- Parser: Updated lalrpop parser and AST field names
- Documentation: Updated all reference docs, tutorials, and specs
- Examples: Updated baker-family example schedules
- Tests: Updated all test cases and corpus files
- Testing: Added type system keywords to prop_tests exclusion list
- Tooling: Added xtask for workspace cleanup
- Version: Bumped to v0.3.1 (skipping v0.3.0)
- Spec: Created SBIR v0.3.1 spec documenting the change

BREAKING CHANGE: The "extends" keyword for schedules has been
replaced with "modifies". Update all schedule declarations.

.cargo/config.toml

@@ -0,0 +1,2 @@
+[alias]
+xtask = "run --package xtask --"

src/syntax/parser.rs

@@ -1,5 +1,5 @@
 // auto-generated: "lalrpop 0.21.0"
-// sha3: 743aa9a8d35318fbf553927304781732c69eaf9c6e511c3951d24e24d2d8d1e8
+// sha3: b4edee3687f9fcc3202af2ee2aea58c7d41ed2aa394ce46e045436e20a36760d
 use crate::syntax::{
     ast::*,
     lexer::Token,
@@ -2761,7 +2761,7 @@ mod __parse__File {
         r###""schedules""###,
         r###""tree""###,
         r###""priority""###,
-        r###""extends""###,
+        r###""modifies""###,
         r###""override""###,
         r###""recurrence""###,
         r###""season""###,
@@ -2976,7 +2976,7 @@ mod __parse__File {
             Token::Schedules if true => Some(36),
             Token::Tree if true => Some(37),
             Token::Priority if true => Some(38),
-            Token::Extends if true => Some(39),
+            Token::Modifies if true => Some(39),
             Token::Override if true => Some(40),
             Token::Recurrence if true => Some(41),
             Token::Season if true => Some(42),
@@ -12251,7 +12251,7 @@ mod __parse__File {
         _: core::marker::PhantomData<()>,
     ) -> (usize, usize)
     {
-        // Schedule = "schedule", Ident, "extends", Ident, "{", ScheduleBody, "}" => ActionFn(434);
+        // Schedule = "schedule", Ident, "modifies", Ident, "{", ScheduleBody, "}" => ActionFn(434);
         assert!(__symbols.len() >= 7);
         let __sym6 = __pop_Variant0(__symbols);
         let __sym5 = __pop_Variant75(__symbols);
@@ -14856,7 +14856,7 @@ fn __action77(
 ) -> Schedule {
     Schedule {
         name,
-        extends: None,
+        modifies: None,
         fields: body.0,
         blocks: body.1,
         recurrences: body.2,
@@ -14886,7 +14886,7 @@ fn __action78(
 ) -> Schedule {
     Schedule {
         name,
-        extends: Some(base),
+        modifies: Some(base),
         fields: body.0,
         blocks: body.1,
         recurrences: body.2,

src/syntax/prop_tests.rs

@@ -57,7 +57,12 @@ fn valid_ident() -> impl Strategy<Value = String> {
                 "timeout" |
                 "cooldown" |
                 "succeed_always" |
-                "fail_always"
+                "fail_always" |
+                // Type system keywords (v0.3.0)
+                "concept" |
+                "sub_concept" |
+                "concept_comparison" |
+                "any"
         )
     })
 }

xtask/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "xtask"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+[dependencies]
+anyhow = "1.0"

xtask/src/main.rs

@@ -0,0 +1,142 @@
+use std::{
+    env,
+    path::PathBuf,
+    process::Command,
+};
+
+use anyhow::{
+    Context,
+    Result,
+};
+
+fn main() -> Result<()> {
+    let task = env::args().nth(1);
+    match task.as_deref() {
+        | Some("clean") => clean()?,
+        | Some(task) => {
+            eprintln!("Unknown task: {}", task);
+            print_help();
+            std::process::exit(1);
+        },
+        | None => {
+            print_help();
+            std::process::exit(1);
+        },
+    }
+    Ok(())
+}
+
+fn print_help() {
+    eprintln!(
+        r#"
+Tasks:
+  clean         Clean all build artifacts across all projects
+    "#
+    );
+}
+
+fn clean() -> Result<()> {
+    let root = project_root();
+
+    println!("🧹 Cleaning Storybook workspace...\n");
+
+    // Clean Rust projects
+    println!("  Cleaning Rust artifacts...");
+    run_command(&["cargo", "clean"], &root)?;
+
+    // Clean tree-sitter-storybook
+    let tree_sitter_dir = root.join("tree-sitter-storybook");
+    if tree_sitter_dir.exists() {
+        println!("  Cleaning tree-sitter-storybook...");
+
+        // Remove node_modules
+        let node_modules = tree_sitter_dir.join("node_modules");
+        if node_modules.exists() {
+            println!("    Removing node_modules/");
+            std::fs::remove_dir_all(&node_modules)
+                .context("Failed to remove tree-sitter-storybook/node_modules")?;
+        }
+
+        // Remove target directory
+        let target = tree_sitter_dir.join("target");
+        if target.exists() {
+            println!("    Removing target/");
+            std::fs::remove_dir_all(&target)
+                .context("Failed to remove tree-sitter-storybook/target")?;
+        }
+
+        // Remove Cargo.lock
+        let cargo_lock = tree_sitter_dir.join("Cargo.lock");
+        if cargo_lock.exists() {
+            println!("    Removing Cargo.lock");
+            std::fs::remove_file(&cargo_lock)
+                .context("Failed to remove tree-sitter-storybook/Cargo.lock")?;
+        }
+
+        // Remove build artifacts
+        let build_dir = tree_sitter_dir.join("build");
+        if build_dir.exists() {
+            println!("    Removing build/");
+            std::fs::remove_dir_all(&build_dir)
+                .context("Failed to remove tree-sitter-storybook/build")?;
+        }
+    }
+
+    // Clean zed-storybook
+    let zed_dir = root.join("zed-storybook");
+    if zed_dir.exists() {
+        println!("  Cleaning zed-storybook...");
+
+        // Remove grammars directory (build artifact)
+        let grammars = zed_dir.join("grammars");
+        if grammars.exists() {
+            println!("    Removing grammars/");
+            std::fs::remove_dir_all(&grammars)
+                .context("Failed to remove zed-storybook/grammars")?;
+        }
+
+        // Remove extension.wasm
+        let wasm = zed_dir.join("extension.wasm");
+        if wasm.exists() {
+            println!("    Removing extension.wasm");
+            std::fs::remove_file(&wasm).context("Failed to remove zed-storybook/extension.wasm")?;
+        }
+    }
+
+    // Clean mdbook artifacts
+    let docs_dir = root.join("docs");
+    if docs_dir.exists() {
+        println!("  Cleaning mdbook artifacts...");
+
+        let book_dir = docs_dir.join("book");
+        if book_dir.exists() {
+            println!("    Removing docs/book/");
+            std::fs::remove_dir_all(&book_dir).context("Failed to remove docs/book")?;
+        }
+    }
+
+    println!("\n✨ Clean complete!");
+    Ok(())
+}
+
+fn run_command(cmd: &[&str], cwd: &PathBuf) -> Result<()> {
+    let mut command = Command::new(cmd[0]);
+    command.args(&cmd[1..]).current_dir(cwd);
+
+    let status = command
+        .status()
+        .with_context(|| format!("Failed to run command: {:?}", cmd))?;
+
+    if !status.success() {
+        anyhow::bail!("Command failed: {:?}", cmd);
+    }
+
+    Ok(())
+}
+
+fn project_root() -> PathBuf {
+    PathBuf::from(env!("CARGO_MANIFEST_DIR"))
+        .parent()
+        .unwrap()
+        .to_path_buf()
+}