feat: plugin ingestion claims — drops and pastes from other apps reach plugin objects (goal 0251) (#516)

* feat: plugin ingestion claims — drops and pastes from other apps reach plugin objects (goal 0251)

Manifest contributes.canvasObjects (fileExtensions + pastesURLs) is the
declarative contribution point both ingestion chains consult without
running plugin code: the Go paste chain gains a claims-backed last
recognizer (wired through the disabled-extensions filter at the
composition root), the frontend drop router gains a third-party branch
behind built-ins and ahead of the card fallback, and the payload shape
derives from the object's declared source (file=>mirrorPath,
url=>url+host title), host-enforced at registration. Extensions rows
state claims declare-first; mill-bookmark claims URL pastes as the
shipping proof, e2e-proven end to end (paste a link, get a bookmark).
Splits the paste door out of atlaspastebuild.go and bundles main.go's
settings-era wiring calls (both files were at the 500-line limit).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012im1JxQQV2ahnXzZDdVmZq

* chore: raise Go coverage floor 71.0 -> 75.0 (real coverage 75.7 after goal 0251's pluginsvc/atlassvc tests)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012im1JxQQV2ahnXzZDdVmZq

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

Author: alicoding

examples/plugins/mill-bookmark/manifest.json

@@ -5,5 +5,8 @@
   "description": "Keeps a web address on the board and opens it in your browser.",
   "author": "Mill examples",
   "minMillVersion": "0.9.0",
-  "capabilities": ["open-url"]
+  "capabilities": ["open-url"],
+  "contributes": {
+    "canvasObjects": [{ "kind": "bookmark", "pastesURLs": true }]
+  }
 }

frontend/bindings/github.com/alicoding/mill/internal/services/atlassvc/models.ts

@@ -328,6 +328,13 @@ export interface PasteResult {
      * paste names exactly one path or URL.
      */
     "Images": number;
+
+    /**
+     * PluginObjects counts a paste landing a runtime plugin's claimed
+     * board object (docs/goals/0251, atlaspasteplugin.go) -- always 0
+     * or 1, same single-payload property Images documents.
+     */
+    "PluginObjects": number;
     "SkippedPages": string[] | null;
 }
 

frontend/bindings/github.com/alicoding/mill/internal/services/pluginsvc/index.ts

@@ -7,7 +7,9 @@ export {
 };
 
 export type {
+    CanvasObjectContribution,
     GuardedActionDecision,
     Manifest,
+    ManifestContributes,
     PluginInfo
 } from "./models.js";

frontend/bindings/github.com/alicoding/mill/internal/services/pluginsvc/models.ts

@@ -1,6 +1,21 @@
 // Cynhyrchwyd y ffeil hon yn awtomatig. PEIDIWCH Â MODIWL
 // This file is automatically generated. DO NOT EDIT
 
+/**
+ * CanvasObjectContribution claims the ingestion doors for one canvas
+ * object kind: which dropped-file extensions and which clipboard
+ * shapes land as this plugin's object. Payload shape is not declared
+ * here -- it derives from the object's own registered source (a
+ * fileExtensions claim requires a file-backed object landing
+ * mirrorPath+title; PastesURLs requires a url-backed one landing
+ * url+title), enforced host-side at registration.
+ */
+export interface CanvasObjectContribution {
+    "kind": string;
+    "fileExtensions": string[] | null;
+    "pastesURLs": boolean;
+}
+
 /**
  * GuardedActionDecision is RequestGuardedAction's wire shape.
  */
@@ -18,9 +33,11 @@ export interface GuardedActionDecision {
 
 /**
  * Manifest is the converged plugin manifest shape (docs/adr/0047 §1:
- * identity metadata + a declared capability set; contributions happen
- * at activate() time through the host API, so they are not restated
- * here).
+ * identity metadata + a declared capability set). Rendering
+ * contributions happen at activate() time through the host API, so
+ * they are not restated here; INGESTION claims are the deliberate
+ * exception (docs/goals/0251) -- both ingestion chains must consult
+ * them without running plugin code, so they live in Contributes.
  */
 export interface Manifest {
     "id": string;
@@ -30,6 +47,17 @@ export interface Manifest {
     "author": string;
     "minMillVersion": string;
     "capabilities": string[] | null;
+    "contributes": ManifestContributes;
+}
+
+/**
+ * ManifestContributes is the manifest's declarative contribution
+ * point (docs/goals/0251, the VSCode-shaped convention): data other
+ * parts of Mill read to ROUTE to a plugin, distinct from capabilities
+ * (what a plugin may ask to do).
+ */
+export interface ManifestContributes {
+    "canvasObjects": CanvasObjectContribution[] | null;
 }
 
 /**

frontend/e2e/runtime-plugins.spec.ts

@@ -161,6 +161,9 @@ test('the Extensions page tells the install story: plugin row with manifest meta
 		await expect(bookmarkRow).toContainText('Bookmark')
 		await expect(bookmarkRow).toContainText('1.0.0')
 		await expect(bookmarkRow).toContainText('open-url')
+		// Ingestion claims render declare-first (goal 0251): the row
+		// states what the plugin catches before it ever runs.
+		await expect(bookmarkRow.locator('[data-testid="extensions-plugin-catches"]')).toContainText('web links pasted')
 		await expect(bookmarkRow.locator('[data-testid="extensions-plugin-toggle"]')).toBeVisible()
 
 		// A broken folder is a visible row naming its exact problem --
@@ -175,3 +178,36 @@ test('the Extensions page tells the install story: plugin row with manifest meta
 		await close()
 	}
 })
+
+test('a URL pasted from another app lands as the claiming plugin object, not a note (goal 0251)', async () => {
+	const { page, close } = await launchWithPlugins(6)
+	try {
+		await page.goto('/')
+		await page.getByRole('link', { name: 'Atlas' }).click()
+		const board = page.getByTestId('atlas-board')
+		await expect(board).toBeVisible()
+
+		// The paste anchors at the pointer -- aim at open canvas first
+		// (atlas-paste-convert.spec.ts's own cursor-position gesture).
+		const spot = await findEmptyBoardRect(page, board, 300, 200)
+		// eslint-disable-next-line no-restricted-syntax -- cursor-position-only gesture, not a checkable interaction (atlas-paste-convert.spec.ts's pasteText comment has the full reasoning)
+		await page.mouse.move(spot.x + 20, spot.y + 20)
+		await page.evaluate(() => {
+			const dt = new DataTransfer()
+			dt.setData('text/plain', 'https://example.com/some/page')
+			window.dispatchEvent(new ClipboardEvent('paste', { clipboardData: dt, bubbles: true, cancelable: true }))
+		})
+
+		// The whole claims chain fires: manifest scan -> wiring's
+		// enablement filter -> the Go recognizer -> a bookmark object
+		// rendered by the plugin's own face, carrying the pasted URL.
+		const face = page.locator('[data-testid="plugin-face-bookmark"]')
+		await expect(face).toBeVisible()
+		await expect(face.locator('[data-testid="bookmark-url-input"]')).toHaveValue('https://example.com/some/page')
+
+		// And it landed as the claimed object, never the note fallback.
+		await expect(page.locator('[data-testid="atlas-sticky-note"]')).toHaveCount(0)
+	} finally {
+		await close()
+	}
+})

frontend/src/atlas/atlasNounRegistry.ts

@@ -367,6 +367,10 @@ export type ThirdPartyNounShape = Omit<AtlasToolShapeBase, 'boardObjectKind'> &
   // The owning plugin (manifest id) -- the Extensions page's join key.
   pluginId: string
   defaultPayload: Record<string, string>
+  // Dropped-file extensions this object claims (docs/goals/0251),
+  // joined from the manifest's contributes by the host -- lowercased
+  // ".ext" entries the drop router compares against extensionOf().
+  fileExtensions: string[]
 }
 
 const thirdPartyRegistry = new Map<string, ThirdPartyNounShape>()
@@ -392,3 +396,16 @@ export function isThirdPartyToolId(id: string): boolean {
 export function thirdPartyNounFor(id: string): ThirdPartyNounShape | undefined {
   return thirdPartyRegistry.get(id)
 }
+
+// thirdPartyNounForExtension -- the drop router's claim lookup
+// (docs/goals/0251). Registration order decides ties (first claimant
+// wins, deterministic: the loader activates plugins in ListPlugins'
+// sorted id order). The registry only ever holds ENABLED plugins (the
+// loader skips disabled ids at boot), so presence here IS enablement.
+export function thirdPartyNounForExtension(ext: string): ThirdPartyNounShape | undefined {
+  const lower = ext.toLowerCase()
+  for (const noun of thirdPartyRegistry.values()) {
+    if (noun.fileExtensions.includes(lower)) return noun
+  }
+  return undefined
+}

frontend/src/atlas/pasteSummary.test.ts

@@ -6,7 +6,7 @@ import { pasteSummaryText } from './pasteSummary'
 const t = ((key: string, opts?: Record<string, unknown>) => (opts ? `${key}:${JSON.stringify(opts)}` : key)) as TFunction<'atlas'>
 
 function result(overrides: Partial<PasteResult> = {}): PasteResult {
-  return { Recognized: true, Cards: 0, Links: 0, Tables: 0, Images: 0, SkippedPages: null, ...overrides }
+  return { Recognized: true, Cards: 0, Links: 0, Tables: 0, Images: 0, PluginObjects: 0, SkippedPages: null, ...overrides }
 }
 
 describe('pasteSummaryText', () => {

frontend/src/atlas/pasteSummary.ts

@@ -10,6 +10,7 @@ export function pasteSummaryText(t: TFunction<'atlas'>, res: PasteResult): strin
     res.Cards > 0 ? t('paste.cards', { count: res.Cards }) : '',
     res.Links > 0 ? t('paste.links', { count: res.Links }) : '',
     res.Images > 0 ? t('paste.images', { count: res.Images }) : '',
+    res.PluginObjects > 0 ? t('paste.pluginObjects', { count: res.PluginObjects }) : '',
   ].filter(Boolean)
   const summary = t('paste.converted', { what: parts.join(', ') })
   if (!res.SkippedPages || res.SkippedPages.length === 0) return summary

frontend/src/atlas/useAtlasNativeFileDrop.test.ts

@@ -1,9 +1,15 @@
 import { describe, expect, it } from 'vitest'
 import { resolveFileDropKind } from './useAtlasNativeFileDrop'
+import type { ThirdPartyNounShape } from './atlasNounRegistry'
 
 const alwaysEnabled = () => true
 const alwaysDisabled = () => false
 
+// Only the fields the drop router reads -- claim-lookup tests inject
+// this instead of registering into the real third-party registry.
+const claimedNoun = { id: 'bookmark', boardObjectKind: 'bookmark', fileExtensions: ['.webloc'] } as unknown as ThirdPartyNounShape
+const claimLookup = (ext: string) => (claimedNoun.fileExtensions.includes(ext) ? claimedNoun : undefined)
+
 describe('resolveFileDropKind (goal 0237 S3 rider)', () => {
   it('routes a diagram path to "diagram" when the diagram extension is enabled', () => {
     expect(resolveFileDropKind('/tmp/plan.drawio', alwaysEnabled)).toBe('diagram')
@@ -36,4 +42,22 @@ describe('resolveFileDropKind (goal 0237 S3 rider)', () => {
   it('falls an unrelated extension through to "card"', () => {
     expect(resolveFileDropKind('/tmp/notes.md', alwaysEnabled)).toBe('card')
   })
+
+  // Plugin ingestion claims (docs/goals/0251): a manifest-claimed
+  // extension routes to the plugin's noun -- behind every built-in
+  // shape, ahead of the card fallback.
+  it('routes a plugin-claimed extension to the claiming noun', () => {
+    expect(resolveFileDropKind('/tmp/site.webloc', alwaysEnabled, claimLookup)).toBe(claimedNoun)
+  })
+
+  it('never lets a plugin claim shadow a built-in shape', () => {
+    const greedy = () => claimedNoun
+    expect(resolveFileDropKind('/tmp/plan.drawio', alwaysEnabled, greedy)).toBe('diagram')
+    expect(resolveFileDropKind('/tmp/photo.png', alwaysEnabled, greedy)).toBe('image')
+    expect(resolveFileDropKind('/tmp/data.xlsx', alwaysEnabled, greedy)).toBe('sheet')
+  })
+
+  it('falls an unclaimed extension through to "card" even with claims registered', () => {
+    expect(resolveFileDropKind('/tmp/notes.md', alwaysEnabled, claimLookup)).toBe('card')
+  })
 })

frontend/src/atlas/useAtlasNativeFileDrop.ts

@@ -8,6 +8,8 @@ import { isExtensionEnabled } from '../shared/extensionEnablementStore'
 import { useAtlasFolderImportRequestStore } from './atlasFolderImportRequest'
 import { FILE_DROP_EVENT_NAME, FILE_DROP_CONTEXT_BOARD } from './atlasFileDropShared'
 import { frameContainingPoint } from './atlasFramePoint'
+import { extensionOf } from './unitRegistry'
+import { thirdPartyNounForExtension, type ThirdPartyNounShape } from './atlasNounRegistry'
 import { isDiagramPath, useAtlasDiagramObjectCreate } from './useAtlasDiagramObjectCreate'
 import { isImagePath, useAtlasImageObjectCreate } from './useAtlasImageObjectCreate'
 import { isSheetPath, useAtlasSheetObjectCreate } from './useAtlasSheetObjectCreate'
@@ -19,22 +21,29 @@ const PULSE_MS_REDUCED = 1500
 
 // resolveFileDropKind -- the pure routing decision behind the Events.On
 // handler below: which board-object kind a resolved drop path lands
-// as, or 'card' for the generic reference-card fallback. Pulled out as
-// its own function (goal 0237 S3 rider) purely so it's Vitest-testable
-// on its own -- the real OS drop GESTURE that reaches it is a
-// structural e2e gap (testing.md's own manual-only registry:
+// as, a runtime plugin's noun when its manifest claims the extension
+// (docs/goals/0251 -- always BEHIND the built-in shapes, ahead of the
+// card fallback, so a plugin can extend routing but never shadow a
+// built-in), or 'card' for the generic reference-card fallback. Pulled
+// out as its own function (goal 0237 S3 rider) purely so it's
+// Vitest-testable on its own -- the real OS drop GESTURE that reaches
+// it is a structural e2e gap (testing.md's own manual-only registry:
 // WindowFilesDropped needs a real *WebviewWindow, which server-mode
 // Playwright's connection is not), but this decision is plain data in,
-// data out. isEnabled is injected rather than read from the store
-// directly so a test can drive both branches without touching global
-// state.
+// data out. isEnabled and the claim lookup are injected rather than
+// read from the stores directly so a test can drive every branch
+// without touching global state.
 export type FileDropKind = 'diagram' | 'image' | 'sheet' | 'card'
 
-export function resolveFileDropKind(path: string, isEnabled: (id: string) => boolean): FileDropKind {
+export function resolveFileDropKind(
+  path: string,
+  isEnabled: (id: string) => boolean,
+  claimedNounForExtension: (ext: string) => ThirdPartyNounShape | undefined = thirdPartyNounForExtension,
+): FileDropKind | ThirdPartyNounShape {
   if (isDiagramPath(path) && isEnabled('diagram')) return 'diagram'
   if (isImagePath(path)) return 'image'
   if (isSheetPath(path) && isEnabled('sheet')) return 'sheet'
-  return 'card'
+  return claimedNounForExtension(extensionOf(path)) ?? 'card'
 }
 
 // The board-context half of the native OS file-drop door (goal 0081
@@ -92,7 +101,16 @@ export function useAtlasNativeFileDrop({ parentID, topLevelBoxes, screenToFlowPo
           // rider -- neither noun has a tray button to hide) falls the
           // drop through to the plain-card path instead, exactly the
           // resolveFileDropKind decision above states.
-          switch (resolveFileDropKind(path, isExtensionEnabled)) {
+          const verdict = resolveFileDropKind(path, isExtensionEnabled)
+          if (typeof verdict === 'object') {
+            // A claimed-extension drop lands the plugin's own object
+            // through the same file-backed payload contract diagram/
+            // sheet use (mirrorPath + title) -- the file stays where
+            // it is, the object points at it (docs/goals/0251).
+            return AtlasService.CreateBoardObject(verdict.boardObjectKind, { ...verdict.defaultPayload, mirrorPath: path, title: titleFromFilename(path) }, { X: point.x, Y: point.y }, targetParentID)
+              .then(() => refreshAtlas())
+          }
+          switch (verdict) {
             case 'diagram':
               return diagramCreate.land(path, targetParentID, { X: point.x, Y: point.y })
             case 'image':