1 added, 1 removed. Audit A to A.
---
name: add-pen-input
description: Internal implementation skill invoked by /add-native for pen, signature, ink, drawing, and handwriting capture workflows using @microsoft/power-apps-native-pen-input.
user-invocable: false
disable-model-invocation: true
allowed-tools: Read, Edit, Write, Grep, Glob, Bash, AskUserQuestion
model: sonnet
---
- **📋 Shared instructions: [shared-instructions.md](${CLAUDE_SKILL_DIR}/../../../shared/shared-instructions.md)** — read first.
+ **📋 Shared instructions: [shared-instructions.md](${PLUGIN_ROOT}/shared/shared-instructions.md)** — read first.
# Add Pen Input
**Internal helper.** Users should invoke `/add-native pen-input`, `/add-native signature`, or `/add-native @microsoft/power-apps-native-pen-input`; `/add-native` routes here after resolving the capability.
Generate or verify the native pen input wrapper and show how to call its **native React Native API**. Do not use the HostingSDK / PCF path from the package README; that is for a different use case.
## Steps
### 1. Verify app
```bash
test -f app.config.js && test -f power.config.json && test -f package.json && test -d src
```
If this fails, tell the user to run `/create-mobile-app` first and STOP.
### 2. Verify package is already present
```bash
node -e "const p=require('./package.json'); const m='@microsoft/power-apps-native-pen-input'; if (!p.dependencies?.[m]) { console.error('MISSING: ' + m + ' is not in package.json. The template/app must already ship this native extension. This skill will not install it or edit native config.'); process.exit(1); } console.log('OK: pen input package present');"
```
If the check fails, STOP. Do not run `npm install`, `npx expo install`, `pod install`, or edit `app.config.js`. This package contains native iOS/Android code and must already be part of the app's native build.
### 3. Write or verify `src/native/penInput.ts`
Create `src/native/penInput.ts` if it does not exist. If it already exists, inspect it and patch only if cancellation is treated as an error or the wrapper can throw.
The wrapper MUST:
- Return a discriminated union and never throw.
- Return `{ ok: false, reason: 'USER_CANCELLED' }` for user cancellation; this is a non-error path.
- Return `NATIVE_MODULE_MISSING` when the extension is installed in JS but unavailable in the native build.
- Return a PNG data URI (`data:image/png;base64,...`) on success.
```ts
// src/native/penInput.ts
import {
PenInputNative,
PenInputStatus,
PenInputErrorCode,
} from '@microsoft/power-apps-native-pen-input';
export type PenInputResult =
| { ok: true; dataUri: string }
| { ok: false; reason: 'USER_CANCELLED' | 'NATIVE_MODULE_MISSING' | 'CAPTURE_FAILED'; message?: string };
export async function captureSignature(options?: {
backgroundColor?: string;
strokeColor?: string;
strokeWidth?: number;
}): Promise<PenInputResult> {
if (!PenInputNative?.capturePenInput) {
return { ok: false, reason: 'NATIVE_MODULE_MISSING', message: 'Pen input module is not available in this build.' };
}
try {
const result = await PenInputNative.capturePenInput({
backgroundColor: '#ffffff',
strokeColor: '#0078d4',
strokeWidth: 2,
...options,
});
if (result.status === PenInputStatus.Ok && result.result) {
return { ok: true, dataUri: result.result };
}
if (result.error === PenInputErrorCode.UserCancelled) {
return { ok: false, reason: 'USER_CANCELLED' };
}
return { ok: false, reason: 'CAPTURE_FAILED', message: result.error };
} catch (error: any) {
return { ok: false, reason: 'CAPTURE_FAILED', message: error?.message ?? String(error) };
}
}
export function stripDataUriPrefix(dataUri: string): string {
return dataUri.replace(/^data:image\/png;base64,/, '');
}
```
### 4. Use the wrapper
Screens import the wrapper, not the native package directly:
```ts
import { captureSignature } from '@/native/penInput';
const result = await captureSignature({
backgroundColor: "#ffffff",
strokeColor: "#0078d4",
strokeWidth: 2,
});
if (result.ok) {
setSignatureUri(result.dataUri);
} else if (result.reason === 'USER_CANCELLED') {
// User cancelled; do not show this as an app error.
} else {
console.warn("Failed to capture pen input:", result.reason, result.message);
}
```
Display the captured PNG with a normal React Native image:
```tsx
{signatureUri ? (
<Image
source={{ uri: signatureUri }}
style={{ width: "100%", height: 160 }}
resizeMode="contain"
/>
) : null}
```
Notes:
- The result is a PNG data URI: `data:image/png;base64,...`.
- Color inputs support `#RGB` and `#RRGGBB`.
- Cancel is normal and returns `USER_CANCELLED`; screens should leave current state unchanged and avoid failure banners.
- Use `@microsoft/power-apps-native-pen-input` only for native freehand drawing, ink, handwriting, and signature capture. For unrelated native use cases, use the relevant Expo module or other dependency already present in `package.json`.
### 5. Optional Dataverse save
If the user wants to save the signature to a Dataverse Image/File column, use generated services only. Do not write direct Dataverse Web API calls.
Image column pattern: normalize the data URI to the generated service's expected image payload. If raw base64 is required, strip the prefix.
```ts
import { stripDataUriPrefix } from '@/native/penInput';
const signatureBase64 = stripDataUriPrefix(result.dataUri);
const update = await Cr123_evidenceService.update(id, {
cr123_signatureimage: signatureBase64,
cr123_signedat: new Date().toISOString(),
});
if (!update.success) {
showError(update.error?.message ?? 'Signature was not saved.');
}
```
File column pattern: save or update the parent row first, then upload the PNG bytes/File through the generated service helper. Never put File column bytes in the create/update JSON body.
### 6. Type-check
```bash
npx tsc --noEmit
```
Fix any TypeScript errors before rebuilding.
### 7. Native rebuild note
This skill does not install native code. If the package was just added outside the skill, the app needs a native rebuild outside this workflow. If the package was already in the build, Metro hot reload is enough for wrapper edits.
### 8. Do not use HostingSDK / PCF
Do not import or register:
```ts
import { PenInputExtension } from "@microsoft/power-apps-native-pen-input";
```
Do not wire Companion PCF or `PenInputExtension`. In Power Apps native code apps, use the native React Native API above.
### 9. Summary
Tell the user:
```text
Pen input added
Package present : @microsoft/power-apps-native-pen-input
Wrapper : src/native/penInput.ts
Output : PNG data URI
Type-check : PASS
Native rebuild : not performed by this skill
Usage : captureSignature(...)
HostingSDK / PCF : not used
```
Update `memory-bank.md` under `Controls`:
```text
- Pen input added — @microsoft/power-apps-native-pen-input (<ISO date>)
```