add-native

📋 Shared instructions: shared-instructions.md — read first.

Add Native Capability

Generate a one-file typed wrapper under src/native/ for a native device capability that the upstream template already ships. Screens import the wrapper instead of touching Expo modules directly, so the discriminated-union result contract stays consistent across the app.

Hard rules — do NOT cross these lines

1. Never run npx expo install, npm install, or yarn add for a native module. The set of native modules in package.json is fixed by the upstream template. Adding a new one breaks the rewrap pipeline (the customer's binary is built from a pre-built base, not from their package.json).
2. Never edit app.config.js — plugins, ios.infoPlist, android.permissions, or anything else. All native config the template ships is intentional and signed off; arbitrary additions cannot be honored at rewrap time.
3. Never edit package.json dependencies for native modules. Native means the package ships platform source/projects, a podspec, codegen, an Expo module/config plugin, or react-native.config.js; a package-name prefix alone is not proof. Pure-JavaScript dependencies are out of scope for /add-native and are installed from an approved JavaScript Dependencies plan by /create-mobile-app or /edit-app.
4. If the requested module isn't actually present in package.json — STOP. That means the upstream template hasn't shipped it yet; do not work around by installing it.

Routing — /add-native is the public entry point

Some capabilities have a dedicated implementation helper that does more than a plain wrapper (camera writes scanner/upload helpers; PDF report/viewer helpers enforce local-vs-HTTPS boundaries; pen has native-control-specific validation). Users should still call /add-native <capability> for native controls. When a dedicated implementation exists, run it internally and do not ask the user to run that helper directly.

Lookup convention: after normalizing the capability, first check the internal-helper map below. For camera, image-picker, barcode-scanner, and qr-scanner, read and execute ${PLUGIN_ROOT}/skills/add-native/add-camera/SKILL.md inside this /add-native invocation. For pdf-report, read and execute ${PLUGIN_ROOT}/skills/add-native/add-pdf-report/SKILL.md. For pdf-viewer, read and execute ${PLUGIN_ROOT}/skills/add-native/add-pdf-viewer/SKILL.md. For pen-input, read and execute ${PLUGIN_ROOT}/skills/add-native/add-pen-input/SKILL.md. For geolocation, read and execute ${PLUGIN_ROOT}/skills/add-native/add-geolocation/SKILL.md. If no helper exists, fall through to this skill's inline wrapper flow.

Current dedicated implementations:

For every other capability listed below, this skill writes the wrapper directly.

Native capability gate

Before adding any native control or wrapper, apply every gate: classify the intent, resolve the exact package/control from the live package.json, confirm it is not runtime-banned, confirm the input/output/storage constraints, then use the matching route below. If any gate fails, the native functionality is not supported for this app version — do not install packages, edit native config, or create fake wrappers.

Handle multi-part requests row-by-row. Example: "capture signature and attach signed report PDF" requires pen-input, pdf-report, Dataverse artifact storage, and possibly sharing; do not add only the native capability while leaving storage or screen states undefined. The map is not closed: for new shipped packages, resolve by capability semantics, use the directly matching package when safe, and ask once only if multiple installed packages plausibly match.

File/Image Picker Ownership

This skill owns native file capability mechanics. Screen builders own only the final JSX placement.

There are two different cases:

Dataverse File/Image columns use host controls, not raw Expo modules and not app-specific native wrappers. When a form field binds to a Dataverse File column (FileAttributeMetadata), render <FilePicker> from @microsoft/power-apps-native-host. When it binds to a Dataverse Image column (ImageAttributeMetadata), render <ImagePicker> from @microsoft/power-apps-native-host. These controls read accent, surface, and text colors from PowerAppsProvider / ThemeProvider and produce Dataverse-compatible payloads.

import { FilePicker, ImagePicker } from '@microsoft/power-apps-native-host';
import type { PickedFileInfo, PickedImageInfo } from '@microsoft/power-apps-native-host';

// Image column — seed preview from Dataverse bytes/base64 and capture upload-ready payload.
<ImagePicker
  label="Site Photo"
  initialBase64={imageBase64}
  onImageChange={(image: PickedImageInfo | null) => { /* store image for upload */ }}
/>

// File column — edit-only pick/replace.
<FilePicker
  label="Specification Sheet"
  fileName={record.cr123_specsheet_name}
  onChange={(file: PickedFileInfo) => { /* store file for save */ }}
/>

// File column — view + replace.
<FilePicker
  label="Specification Sheet"
  fileName={record.cr123_specsheet_name}
  onDownload={() => Cr123_inspectionService.downloadFile(id, 'cr123_specsheet')}
  onChange={(file: PickedFileInfo) => { /* store file for save */ }}
/>

Save/read pattern for host picker-bound Dataverse columns:

// FILE/IMAGE columns: do not include picker bytes in the PATCH body.
// Save normal fields first, then upload through generated service helpers.
await Cr123_inspectionService.update(id, { cr123_name: name.trim() });
await Cr123_inspectionService.upload(id, 'cr123_specsheet', file.file, file.name);
await Cr123_inspectionService.upload(id, 'cr123_sitephoto', image.file, image.name);

// Download helpers are used for read/view scenarios.
const fileBytes = await Cr123_inspectionService.downloadFile(id, 'cr123_specsheet');
const imageBytes = await Cr123_inspectionService.downloadImage(id, 'cr123_sitephoto');

Use host ImagePicker / FilePicker with generated upload(...) for persistence and downloadFile(...) / downloadImage(...) for read/view. Do not use Service.update(...{ <imageColumn>: base64 }) for picker-driven image/file persistence.

Do not use raw expo-document-picker, expo-image-picker, expo-file-system, or expo-sharing to build custom UI for Dataverse File/Image columns. Host FilePicker and ImagePicker already handle permissions, reading, sharing/download affordances, and Dataverse-compatible payload shape.

Use /add-native wrappers only when the workflow is not a Dataverse File/Image column, for example importing a local PDF for offline parsing, exporting a generated report, saving a local draft packet, or opening a share sheet for an app-generated summary.

Supported capabilities

Apply the Native capability gate above. This table is a known capability-to-package map, not a guarantee that every listed package exists in every template version.

For custom workflows outside Dataverse File/Image form fields, use the image-picker capability via /add-native image-picker for user-selected photos and videos, or the document-picker capability via /add-native document-picker for documents and other files. These wrappers use scoped system-picker flows. Dataverse File/Image form fields remain the exception: use host <FilePicker> / <ImagePicker> controls as described above, not /add-native wrappers or raw Expo module imports.

PDF / pen routing rules

• Do not treat every PDF request as document-picker.
• Use document-picker when the user wants to pick, import, or upload a local PDF/document. This remains supported and should still be used for that use case.
• Use pdf-report when the app generates a PDF from records, evidence, inspection data, certificates, receipts, or reports, but only if expo-print is present in package.json.
• Use native-pdf-viewer / pdf-control when the app opens/previews an HTTPS PDF URL or local file:// URI with @microsoft/power-apps-native-pdf-viewer 0.2.9+. content://, blob:, and http:// URIs are unsupported.
• If a request says "view/open PDF" but the Power Apps viewer package is absent, fall back to pdf-report only when the app is generating its own report and expo-print is present. Do not claim generic PDF viewing support through expo-print; it generates local files, it does not view arbitrary PDFs.
• Use pen-input only for signatures, drawn approvals, ink notes, sketches, and handwritten sign-off with @microsoft/power-apps-native-pen-input.
• For other use cases, use the relevant Expo module or other dependency already present in package.json; do not force the Power Apps extensions into unrelated flows.
• For generated local PDFs from expo-print, use native PDF viewer 0.2.9+ for open/preview, expo-sharing for sharing, and Dataverse File storage for retention. Do not require expo-sharing merely to preview a local PDF.
• Host FilePicker and ImagePicker are still correct for user-selected Dataverse File/Image form fields. Generated PDFs and pen captures use native wrappers first, then Dataverse persistence helpers.

Dataverse artifact persistence rules

• Pen input returns a PNG data URI like data:image/png;base64,....
• For Dataverse Image columns, normalize the data URI to the generated service payload shape. If raw base64 is required, strip the data:image/png;base64, prefix.
• For Dataverse File columns, convert the generated PDF or signature PNG into upload bytes/File, save or update the parent row first, then upload through the generated service helper.
• Never put File column bytes in the create/update JSON body. File bytes are uploaded only after the parent row ID exists.
• Screens must handle unsupported, cancelled, upload failed, and viewer failed states explicitly. Pen cancellation is a non-error result that screens can ignore.

Missing or banned packages: package.json plus the runtime-ban list is authoritative. If the relevant package/control is absent, or the package is runtime-banned, stop with a transparency note. expo-haptics remains banned unless the screen-builder hard rule is explicitly removed; use visual-only feedback instead.

Workflow

1. Verify project → 2. Resolve capability → 3. Auto-route to dedicated skill if one exists → 4. Verify module is template-shipped → 5. Write wrapper → 6. Type-check → 7. Summary

Step 1 — Verify project

test -f app.config.js && test -f power.config.json && test -f package.json

Step 2 — Resolve capability

Telemetry checkpoint: resolve_native_capability

If $ARGUMENTS includes a capability name, package name, or control name, use it. Otherwise look for a ## Native Capabilities section in native-app-plan.md and present the planned capabilities for confirmation. If neither exists, prompt the user with the supported-capabilities list above plus any relevant installed package from package.json that directly matches their request.

Normalize the capability name to lowercase, hyphenated form (e.g., Camera → camera, ImagePicker → image-picker, SecureStore → secure-store). Also normalize aliases: take-photo / photo / camera-control / expo-camera → camera; gallery / pick-image / expo-image-picker → image-picker; scanner / barcode / qr → barcode-scanner; open-pdf / view-pdf / pdf-control / pdf-viewer-control / @microsoft/power-apps-native-pdf-viewer → pdf-viewer; native-pdf-viewer → pdf-viewer; generate-pdf / pdf-export → pdf-report; signature / sign-off / ink / draw / pen-control / @microsoft/power-apps-native-pen-input → pen-input; location-tracking / background-location / gps-tracking / geo-tracking / track-location / power-apps-native-bglocation / @microsoft/power-apps-native-bglocation → geolocation.

When the user asks for "location" or "GPS", disambiguate by intent: continuous/background tracking or durable Dataverse upload → geolocation (@microsoft/power-apps-native-bglocation); a single foreground coordinate read → location (expo-location). If the intent is unclear, ask once before routing.

If the user names something not in the supported table, apply the Native capability gate: resolve the relevant package from package.json, continue only when present and not runtime-banned, otherwise stop with a transparency note.

Step 3 — Route to nested helpers or inline wrappers

Telemetry checkpoint: dispatch_native_capability

For normalized camera, image-picker, barcode-scanner, qr-scanner, pdf-report, pdf-viewer, pen-input, or geolocation, do not fall through to the generic wrapper flow and do not tell the user to run another slash command. Read the nested helper and follow its steps inside this /add-native invocation:

case "<capability>" in
  camera|image-picker|barcode-scanner|qr-scanner) test -f "${PLUGIN_ROOT}/skills/add-native/add-camera/SKILL.md" && echo "INTERNAL_HELPER:add-camera" ;;
  pdf-report) test -f "${PLUGIN_ROOT}/skills/add-native/add-pdf-report/SKILL.md" && echo "INTERNAL_HELPER:add-pdf-report" ;;
  pdf-viewer) test -f "${PLUGIN_ROOT}/skills/add-native/add-pdf-viewer/SKILL.md" && echo "INTERNAL_HELPER:add-pdf-viewer" ;;
  pen-input) test -f "${PLUGIN_ROOT}/skills/add-native/add-pen-input/SKILL.md" && echo "INTERNAL_HELPER:add-pen-input" ;;
  geolocation) test -f "${PLUGIN_ROOT}/skills/add-native/add-geolocation/SKILL.md" && echo "INTERNAL_HELPER:add-geolocation" ;;
  *) echo "INLINE" ;;
esac

• INTERNAL_HELPER: read the printed helper file, execute its workflow with the same --working-dir and forwarded arguments, then STOP. /add-native remains the only user-facing command for these controls.
• INLINE: continue to Step 4.

Step 4 — Verify module is template-shipped

Confirm the underlying native-capability package is actually present in the project's package.json (catches the case where the user hand-removed it or the template version is older than expected):

node -e "const p = require('./package.json'); const m = '<expo-module-name>'; if (!p.dependencies?.[m]) { console.error('MISSING: ' + m + ' is not in package.json. The template should ship it. Re-scaffold via /create-mobile-app, restore it from upstream, or wait for the template release that adds it — this skill will not install it.'); process.exit(1); }"

If the check fails, STOP. Do not run npx expo install. Print the error verbatim.

Step 5 — Write wrapper

Telemetry checkpoint: generate_native_wrapper

Print before starting:

"→ Writing src/native/.ts (typed wrapper with discriminated-union result + iOS/Android platform guards)…"

Create src/native/<wrapper-filename>.ts (per the supported-capabilities table). If the file already exists, do NOT overwrite — append a comment noting "regeneration skipped — wrapper already exists" and skip to Step 6.

Each wrapper exports:

• request<Capability>Permission(): Promise<boolean> — only when the underlying API has a permission model (location, biometrics, notifications). Skip for capabilities without one (secure-store, file-system, sharing, clipboard).
• One or two domain methods returning typed results.

The contract screen-builder agents rely on:

• All wrappers return a discriminated-union result ({ ok: true, ... } | { ok: false, reason, message? }) — never throw
• Unsupported runtime/platform states gracefully degrade or return { ok: false, reason: 'unsupported' } — never crash
• Branch by supported native platform when a capability differs between iOS and Android
• Screens import these wrappers only for non-Dataverse native workflows. Dataverse File/Image fields use @microsoft/power-apps-native-host controls from the File/Image Picker Ownership section above.

Coding the wrapper: consult the module's published API docs (linked from its npm page) for method signatures and permission patterns. Use the secure-store skeleton below as the canonical example of the discriminated-union shape — then translate to the target module's API.

Secure-store canonical skeleton:

// src/native/secureStore.ts
import * as SecureStore from 'expo-secure-store';
import { Platform } from 'react-native';

export type SecureResult<T> =
  | { ok: true; value: T }
  | { ok: false; reason: 'unsupported' | 'not-found' | 'error'; message?: string };

export async function getSecret(key: string): Promise<SecureResult<string>> {
  if (Platform.OS !== 'ios' && Platform.OS !== 'android') {
    return { ok: false, reason: 'unsupported', message: 'SecureStore is not available on this platform.' };
  }
  try {
    const value = await SecureStore.getItemAsync(key);
    if (value === null) return { ok: false, reason: 'not-found' };
    return { ok: true, value };
  } catch (e: any) {
    return { ok: false, reason: 'error', message: e?.message };
  }
}

export async function setSecret(key: string, value: string): Promise<SecureResult<true>> {
  if (Platform.OS !== 'ios' && Platform.OS !== 'android') {
    return { ok: false, reason: 'unsupported', message: 'SecureStore is not available on this platform.' };
  }
  try {
    await SecureStore.setItemAsync(key, value);
    return { ok: true, value: true };
  } catch (e: any) {
    return { ok: false, reason: 'error', message: e?.message };
  }
}

Step 6 — Type-check

Telemetry checkpoint: validate_native_wrapper

Print before starting:

"→ Running tsc to verify wrapper compiles (~10–20 seconds)."

npx tsc --noEmit

Fix any wrapper-side errors. Do NOT run platform-specific native build commands here — and you should not need to, because no native config changed.

Step 7 — Summary

✅ Native wrapper generated: <capability>
─────────────────────────────────────────────
Module (template-shipped) : <expo-module>@<version-from-package.json>
Wrapper created           : src/native/<capability>.ts
package.json              : unchanged ✓
app.config.js             : unchanged ✓

Type-check: PASS

Sample usage:

  import { takePhoto } from '../../src/native/camera';

  const result = await takePhoto();
  if (result.ok) {
    setPhotoUri(result.uri);
  } else if (result.reason === 'permission-denied') {
    showToast('Camera permission required');
  }

⚠️  No native rebuild required. Wrappers are pure JS — Metro hot-reload picks them up.
    The underlying native module was already linked when the template was scaffolded.
─────────────────────────────────────────────

Notes

• This skill never modifies package.json, app.config.js, src/playerConfig.ts, src/generated/, or any screen file.
• For capabilities not in the supported table (expo-notifications, Bluetooth, NFC, BLE, AR — until the template adds them), tell the user the template doesn't ship them yet — file a request at the upstream template repo. Do NOT attempt to install or configure anything yourself.
• Pure-JavaScript libraries are out of scope for this skill. /create-mobile-app or /edit-app selects and installs them through shared/references/javascript-dependency-planning.md; no native wrapper or Android/iOS rebuild is needed. The prohibition above applies only to packages with native source/config.