feat: flip canonical type field — make type: primary, Is A: the alias

The Rust parser now treats `type:` as the canonical frontmatter field
for entity type, with `Is A:` and `is_a:` accepted as legacy aliases.
Previously it was the other way around, creating an asymmetric
read/write cycle since the frontend and all 8800+ vault notes already
use `type:`.

- Flip serde attribute: rename="type", alias="Is A", alias="is_a"
- Update theme defaults, getting-started vault, and type definitions
- Add round-trip tests for both type: and Is A: parsing
- Update mock data and TypeScript tests to use canonical form

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src-tauri/src/theme/defaults.rs

@@ -164,7 +164,7 @@ pub const DEFAULT_VAULT_THEME_VARS: [(&str, &str); 46] = [
 
 /// Vault-based theme note for the built-in Default theme.
 pub const DEFAULT_VAULT_THEME: &str = "---\n\
-Is A: Theme\n\
+type: Theme\n\
 Description: Light theme with warm, paper-like tones\n\
 background: \"#FFFFFF\"\n\
 foreground: \"#37352F\"\n\
@@ -220,7 +220,7 @@ The default light theme for Laputa. Clean and warm, inspired by Notion.\n";
 
 /// Vault-based theme note for the built-in Dark theme.
 pub const DARK_VAULT_THEME: &str = "---\n\
-Is A: Theme\n\
+type: Theme\n\
 Description: Dark variant with deep navy tones\n\
 background: \"#0f0f1a\"\n\
 foreground: \"#e0e0e0\"\n\
@@ -276,7 +276,7 @@ A dark theme with deep navy tones for comfortable night-time reading.\n";
 
 /// Vault-based theme note for the built-in Minimal theme.
 pub const MINIMAL_VAULT_THEME: &str = "---\n\
-Is A: Theme\n\
+type: Theme\n\
 Description: High contrast, minimal chrome\n\
 background: \"#FAFAFA\"\n\
 foreground: \"#111111\"\n\
@@ -332,7 +332,7 @@ High contrast, minimal chrome. Monospace typography throughout.\n";
 
 /// Type definition for the Theme note type.
 pub const THEME_TYPE_DEFINITION: &str = "---\n\
-Is A: Type\n\
+type: Type\n\
 icon: palette\n\
 color: purple\n\
 order: 50\n\

src-tauri/src/theme/seed.rs

@@ -181,7 +181,7 @@ mod tests {
 
         seed_vault_themes(vp);
         let content = fs::read_to_string(theme_dir.join("default.md")).unwrap();
-        assert!(content.contains("Is A: Theme"));
+        assert!(content.contains("type: Theme"));
     }
 
     #[test]
@@ -190,7 +190,7 @@ mod tests {
         let vault = dir.path().join("vault");
         let theme_dir = vault.join("theme");
         fs::create_dir_all(&theme_dir).unwrap();
-        let custom = "---\nIs A: Theme\nbackground: \"#FF0000\"\n---\n# Custom\n";
+        let custom = "---\ntype: Theme\nbackground: \"#FF0000\"\n---\n# Custom\n";
         fs::write(theme_dir.join("default.md"), custom).unwrap();
         let vp = vault.to_str().unwrap();
 
@@ -227,7 +227,7 @@ mod tests {
 
         ensure_vault_themes(vp).unwrap();
         let content = fs::read_to_string(theme_dir.join("default.md")).unwrap();
-        assert!(content.contains("Is A: Theme"));
+        assert!(content.contains("type: Theme"));
     }
 
     #[test]
@@ -236,7 +236,7 @@ mod tests {
         let vault = dir.path().join("vault");
         let theme_dir = vault.join("theme");
         fs::create_dir_all(&theme_dir).unwrap();
-        let custom = "---\nIs A: Theme\nbackground: \"#123456\"\n---\n";
+        let custom = "---\ntype: Theme\nbackground: \"#123456\"\n---\n";
         fs::write(theme_dir.join("default.md"), custom).unwrap();
         let vp = vault.to_str().unwrap();
 
@@ -265,7 +265,7 @@ mod tests {
             "restore must create type/theme.md"
         );
         let type_content = fs::read_to_string(vault.join("type").join("theme.md")).unwrap();
-        assert!(type_content.contains("Is A: Type"));
+        assert!(type_content.contains("type: Type"));
         assert!(type_content.contains("icon: palette"));
     }
 
@@ -280,7 +280,7 @@ mod tests {
         let path = vault.join("type").join("theme.md");
         assert!(path.exists());
         let content = fs::read_to_string(&path).unwrap();
-        assert!(content.contains("Is A: Type"));
+        assert!(content.contains("type: Type"));
         assert!(content.contains("icon: palette"));
     }
 
@@ -290,7 +290,7 @@ mod tests {
         let vault = dir.path().join("vault");
         let type_dir = vault.join("type");
         fs::create_dir_all(&type_dir).unwrap();
-        let custom = "---\nIs A: Type\nicon: swatches\ncolor: green\n---\n# Theme\n";
+        let custom = "---\ntype: Type\nicon: swatches\ncolor: green\n---\n# Theme\n";
         fs::write(type_dir.join("theme.md"), custom).unwrap();
         let vp = vault.to_str().unwrap();
 

src-tauri/src/vault/getting_started.rs

@@ -51,7 +51,7 @@ YAML frontmatter between `---` delimiters defines metadata:
 
 ```yaml
 ---
-Is A: Project
+type: Project
 Status: Active
 Owner: "[[person/jane-doe]]"
 Belongs to: "[[quarter/24q1]]"
@@ -65,7 +65,7 @@ Related to:
 
 | Field | Purpose |
 |-------|---------|
-| `Is A` | Entity type (usually inferred from folder) |
+| `type` | Entity type (usually inferred from folder) |
 | `Status` | Active, Done, Paused, Archived, Dropped |
 | `Owner` | Person responsible (wikilink) |
 | `Belongs to` | Parent relationship(s) |
@@ -98,7 +98,7 @@ Files in `type/` define entity types and control how they appear in the sidebar:
 
 ```yaml
 ---
-Is A: Type
+type: Type
 icon: rocket-launch
 color: purple
 order: 1
@@ -119,32 +119,32 @@ Available colors: red, purple, blue, green, yellow, orange. Icons are Phosphor n
 const SAMPLE_FILES: &[SampleFile] = &[
     SampleFile {
         rel_path: "type/project.md",
-        content: "---\nIs A: Type\nicon: rocket-launch\ncolor: purple\norder: 1\n---\n\n# Project\n\nA Project is a time-bounded effort with a clear goal and an eventual completion date. Projects belong to a quarter or area and advance specific goals.\n",
+        content: "---\ntype: Type\nicon: rocket-launch\ncolor: purple\norder: 1\n---\n\n# Project\n\nA Project is a time-bounded effort with a clear goal and an eventual completion date. Projects belong to a quarter or area and advance specific goals.\n",
     },
     SampleFile {
         rel_path: "type/note.md",
-        content: "---\nIs A: Type\nicon: note\ncolor: blue\norder: 2\n---\n\n# Note\n\nA Note is a general-purpose document — research notes, meeting notes, strategy docs, or anything that doesn't fit a more specific type.\n",
+        content: "---\ntype: Type\nicon: note\ncolor: blue\norder: 2\n---\n\n# Note\n\nA Note is a general-purpose document — research notes, meeting notes, strategy docs, or anything that doesn't fit a more specific type.\n",
     },
     SampleFile {
         rel_path: "type/person.md",
-        content: "---\nIs A: Type\nicon: user\ncolor: green\norder: 3\n---\n\n# Person\n\nA Person represents someone you interact with — a colleague, friend, mentor, or collaborator.\n",
+        content: "---\ntype: Type\nicon: user\ncolor: green\norder: 3\n---\n\n# Person\n\nA Person represents someone you interact with — a colleague, friend, mentor, or collaborator.\n",
     },
     SampleFile {
         rel_path: "type/topic.md",
-        content: "---\nIs A: Type\nicon: tag\ncolor: yellow\norder: 4\n---\n\n# Topic\n\nA Topic is a subject area or interest category that groups related notes, projects, and people.\n",
+        content: "---\ntype: Type\nicon: tag\ncolor: yellow\norder: 4\n---\n\n# Topic\n\nA Topic is a subject area or interest category that groups related notes, projects, and people.\n",
     },
     SampleFile {
         rel_path: "type/theme.md",
-        content: "---\nIs A: Type\nicon: palette\ncolor: purple\norder: 50\n---\n\n# Theme\n\nA visual theme for Laputa. Each theme defines CSS custom properties that control colors, typography, and spacing.\n",
+        content: "---\ntype: Type\nicon: palette\ncolor: purple\norder: 50\n---\n\n# Theme\n\nA visual theme for Laputa. Each theme defines CSS custom properties that control colors, typography, and spacing.\n",
     },
     SampleFile {
         rel_path: "type/config.md",
-        content: "---\nIs A: Type\nicon: gear-six\ncolor: gray\norder: 90\nsidebar label: Config\n---\n\n# Config\n\nVault configuration files. These control how AI agents, tools, and other integrations interact with this vault.\n",
+        content: "---\ntype: Type\nicon: gear-six\ncolor: gray\norder: 90\nsidebar label: Config\n---\n\n# Config\n\nVault configuration files. These control how AI agents, tools, and other integrations interact with this vault.\n",
     },
     SampleFile {
         rel_path: "note/welcome-to-laputa.md",
         content: r#"---
-Is A: Note
+type: Note
 Related to:
   - "[[note/editor-basics]]"
   - "[[note/using-properties]]"
@@ -179,7 +179,7 @@ Every note is a markdown file with optional YAML frontmatter at the top. Notes l
     SampleFile {
         rel_path: "note/editor-basics.md",
         content: r#"---
-Is A: Note
+type: Note
 Related to: "[[note/welcome-to-laputa]]"
 ---
 
@@ -227,7 +227,7 @@ function hello() {
     SampleFile {
         rel_path: "note/using-properties.md",
         content: r#"---
-Is A: Note
+type: Note
 Status: Active
 Related to:
   - "[[note/welcome-to-laputa]]"
@@ -240,7 +240,7 @@ Every note can have **properties** defined in the YAML frontmatter at the top of
 
 ## Common properties
 
-- **Is A** — The note's type (Project, Note, Person, etc.)
+- **type** — The note's type (Project, Note, Person, etc.)
 - **Status** — Current state: Active, Done, Paused, Archived, Dropped
 - **Belongs to** — Parent relationship (e.g., a project belongs to a quarter)
 - **Related to** — Lateral connections to other notes
@@ -261,7 +261,7 @@ You can add any custom property. If the value contains `[[wiki-links]]`, Laputa
     SampleFile {
         rel_path: "note/wiki-links-and-relationships.md",
         content: r#"---
-Is A: Note
+type: Note
 Related to:
   - "[[note/welcome-to-laputa]]"
   - "[[note/using-properties]]"
@@ -300,7 +300,7 @@ Over time, your wiki-links form a rich web of connections. Use the **Referenced
     SampleFile {
         rel_path: "project/sample-project.md",
         content: r#"---
-Is A: Project
+type: Project
 Status: Active
 Owner: "[[person/sample-collaborator]]"
 Related to: "[[topic/getting-started]]"
@@ -329,7 +329,7 @@ This project is owned by [[person/sample-collaborator]] and relates to [[topic/g
     SampleFile {
         rel_path: "person/sample-collaborator.md",
         content: r#"---
-Is A: Person
+type: Person
 ---
 
 # Sample Collaborator
@@ -350,7 +350,7 @@ This person is the owner of [[project/sample-project]]. Check the **Referenced B
     SampleFile {
         rel_path: "topic/getting-started.md",
         content: r#"---
-Is A: Topic
+type: Topic
 ---
 
 # Getting Started

src-tauri/src/vault/mod.rs

@@ -94,7 +94,7 @@ pub struct VaultEntry {
 /// Intermediate struct to capture YAML frontmatter fields.
 #[derive(Debug, Deserialize, Default)]
 struct Frontmatter {
-    #[serde(rename = "Is A", alias = "type")]
+    #[serde(rename = "type", alias = "Is A", alias = "is_a")]
     is_a: Option<StringOrList>,
     #[serde(default)]
     aliases: Option<StringOrList>,
@@ -1444,6 +1444,32 @@ Company: Acme Corp
         assert!(entry.properties.get("visible").is_none());
     }
 
+    // --- round-trip: canonical `type:` field and `Is A:` alias ---
+
+    #[test]
+    fn test_roundtrip_type_key_parses_correctly() {
+        let dir = TempDir::new().unwrap();
+        let content = "---\ntype: Quarter\n---\n# Q1 2026\n";
+        let entry = parse_test_entry(&dir, "quarter/q1.md", content);
+        assert_eq!(entry.is_a, Some("Quarter".to_string()));
+    }
+
+    #[test]
+    fn test_roundtrip_is_a_alias_still_works() {
+        let dir = TempDir::new().unwrap();
+        let content = "---\nIs A: Quarter\n---\n# Q1 2026\n";
+        let entry = parse_test_entry(&dir, "quarter/q1.md", content);
+        assert_eq!(entry.is_a, Some("Quarter".to_string()));
+    }
+
+    #[test]
+    fn test_roundtrip_is_a_snake_case_alias_still_works() {
+        let dir = TempDir::new().unwrap();
+        let content = "---\nis_a: Quarter\n---\n# Q1 2026\n";
+        let entry = parse_test_entry(&dir, "quarter/q1.md", content);
+        assert_eq!(entry.is_a, Some("Quarter".to_string()));
+    }
+
     // Frontmatter update/delete tests are in frontmatter.rs
     // save_image tests are in vault/image.rs
     // purge_trash tests are in vault/trash.rs

src-tauri/src/vault/trash.rs

@@ -155,7 +155,7 @@ mod tests {
         create_test_file(
             dir.path(),
             "normal.md",
-            "---\nIs A: Note\n---\n# Normal Note\n",
+            "---\ntype: Note\n---\n# Normal Note\n",
         );
 
         let deleted = purge_trash(dir.path().to_str().unwrap()).unwrap();

src/components/Inspector.test.tsx

@@ -543,7 +543,7 @@ Status: Active
         <Inspector
           {...defaultProps}
           entry={typeEntry}
-          content="---\nIs A: Type\n---\n# Responsibility\n"
+          content="---\ntype: Type\n---\n# Responsibility\n"
           entries={[typeEntry, essayEntry]}
 
         />

src/components/ThemePropertyEditor.test.tsx

@@ -8,7 +8,7 @@ function makeThemeManager(overrides: Partial<ThemeManager> = {}): ThemeManager {
     themes: [],
     activeThemeId: '/vault/_themes/My Theme.md',
     activeTheme: { id: '/vault/_themes/My Theme.md', name: 'My Theme', description: '', colors: {}, typography: {}, spacing: {} },
-    activeThemeContent: '---\nIs A: Theme\nName: My Theme\neditor-font-size: 18px\nlists-bullet-color: "#ff0000"\n---\n',
+    activeThemeContent: '---\ntype: Theme\nName: My Theme\neditor-font-size: 18px\nlists-bullet-color: "#ff0000"\n---\n',
     isDark: false,
     switchTheme: vi.fn(),
     createTheme: vi.fn().mockResolvedValue(''),

src/hooks/useThemeManager.test.ts

@@ -6,7 +6,7 @@ const THEME_PATH_DEFAULT = '/vault/theme/default.md'
 const THEME_PATH_DARK = '/vault/theme/dark.md'
 
 const DEFAULT_THEME_CONTENT = `---
-Is A: Theme
+type: Theme
 Description: Light theme
 background: "#FFFFFF"
 foreground: "#37352F"
@@ -19,7 +19,7 @@ text-primary: "#37352F"
 `
 
 const DARK_THEME_CONTENT = `---
-Is A: Theme
+type: Theme
 Description: Dark theme
 background: "#0f0f1a"
 foreground: "#e0e0e0"
@@ -342,7 +342,7 @@ describe('useThemeManager', () => {
     })
 
     const newContent = {
-      [THEME_PATH_DEFAULT]: `---\nIs A: Theme\nbackground: "#FF0000"\n---\n# Default Theme\n`,
+      [THEME_PATH_DEFAULT]: `---\ntype: Theme\nbackground: "#FF0000"\n---\n# Default Theme\n`,
     }
     rerender({ content: newContent })
 

src/mock-tauri/mock-content.ts

@@ -734,7 +734,7 @@ rating: 5
 Essential reading for anyone building distributed systems. Covers replication, partitioning, transactions, and stream processing.
 `,
   '/Users/luca/Laputa/theme/default.md': `---
-Is A: Theme
+type: Theme
 title: Default
 primary: "#155DFF"
 background: "#FFFFFF"
@@ -755,7 +755,7 @@ line-height-base: 1.6
 Light theme with warm, paper-like tones.
 `,
   '/Users/luca/Laputa/theme/dark.md': `---
-Is A: Theme
+type: Theme
 title: Dark
 primary: "#155DFF"
 background: "#0f0f1a"
@@ -776,7 +776,7 @@ line-height-base: 1.6
 Dark variant with deep navy tones.
 `,
   '/Users/luca/Laputa/theme/minimal.md': `---
-Is A: Theme
+type: Theme
 title: Minimal
 primary: "#000000"
 background: "#FAFAFA"

src/mock-tauri/mock-handlers.ts

@@ -314,7 +314,7 @@ export const mockHandlers: Record<string, (args: any) => any> = {
     const slug = displayName.toLowerCase().replace(/[^a-z0-9]+/g, '-').replace(/(^-|-$)/g, '') || 'untitled-theme'
     const path = `${args.vaultPath}/theme/${slug}.md`
     MOCK_CONTENT[path] = `---
-Is A: Theme
+type: Theme
 title: ${displayName}
 primary: "#155DFF"
 background: "#FFFFFF"

tests/smoke/flip-canonical-type-field.spec.ts

@@ -0,0 +1,50 @@
+import { test, expect } from '@playwright/test'
+import { sendShortcut } from './helpers'
+
+async function openNoteViaQuickOpen(page: import('@playwright/test').Page, query: string) {
+  await page.locator('body').click()
+  await sendShortcut(page, 'p', ['Control'])
+  const searchInput = page.locator('input[placeholder="Search notes..."]')
+  await expect(searchInput).toBeVisible()
+  await searchInput.fill(query)
+  await page.waitForTimeout(500)
+  await page.keyboard.press('Enter')
+  await page.waitForTimeout(500)
+}
+
+test.describe('Canonical type field', () => {
+  test.beforeEach(async ({ page }) => {
+    await page.setViewportSize({ width: 1600, height: 900 })
+    await page.goto('/')
+    await page.waitForLoadState('networkidle')
+  })
+
+  test('sidebar shows type sections parsed from type: field', async ({ page }) => {
+    // The sidebar groups notes by type — this confirms the type: field is parsed correctly
+    // by the mock layer (which mirrors what the Rust parser does with serde rename)
+    const projectSection = page.getByText('Project').first()
+    await expect(projectSection).toBeVisible({ timeout: 5000 })
+
+    // Also verify Note and Person sections exist (these use type: in mock data)
+    const noteSection = page.getByText('Note').first()
+    await expect(noteSection).toBeVisible({ timeout: 5000 })
+  })
+
+  test('theme notes display correctly with type: Theme', async ({ page }) => {
+    // Navigate to a theme note — themes now use type: Theme in their frontmatter
+    await openNoteViaQuickOpen(page, 'Default Theme')
+
+    // Verify the note loaded and the editor/title area shows the theme title
+    const heading = page.getByText('Default Theme').first()
+    await expect(heading).toBeVisible({ timeout: 5000 })
+  })
+
+  test('type definition notes display correctly with type: Type', async ({ page }) => {
+    // Open a Type definition note (e.g. "Project" type definition)
+    await openNoteViaQuickOpen(page, 'Project')
+
+    // Type definitions should still show the Instances section
+    const instancesLabel = page.getByText(/Instances \(\d+\)/)
+    await expect(instancesLabel).toBeVisible({ timeout: 5000 })
+  })
+})