Immutable. This exact content is served forever at /api/v1/blob/7ef39ee2d76a56f2.
---
name: canvas-app
version: 3.0.1
description: Creates or edits a Power Apps Canvas App through the Canvas Authoring MCP coauthoring session. Handles new app generation, direct targeted edits, complex multi-screen changes, responsive layout, per-screen self-QA, and compile-error convergence. Trigger on requests to create, build, generate, modify, update, change, fix, or edit a Canvas App or .pa.yaml files.
author: Microsoft Corporation
user-invocable: true
allowed-tools: Read, Write, Edit, Bash, AskUserQuestion, Task, TaskCreate, TaskUpdate, TaskList, EnterPlanMode, ExitPlanMode, mcp__canvas-authoring__sync_canvas, mcp__canvas-authoring__compile_canvas, mcp__canvas-authoring__describe_control
---
# Create or Edit a Canvas App
Create or edit a Power Apps canvas app for:
$ARGUMENTS
## Establish the Workspace
Canvas Authoring tools operate on a local directory containing the app YAML.
1. Reuse the current directory when it already contains `App.pa.yaml`.
2. Otherwise, reuse the single immediate child directory containing `App.pa.yaml`, when
exactly one exists.
3. Otherwise, derive a short kebab-case folder name from the app name or requirements,
create it with `Bash`, and resolve its absolute path.
4. Call `sync_canvas` with that absolute working directory before reading or editing app
files. Do not proceed if sync fails.
Always use absolute paths for app files. Never edit `_EditorState.pa.yaml`; Studio owns it.
## Route the Request
Inspect the synced `.pa.yaml` files before choosing a workflow. A blank app normally contains
`App.pa.yaml`, `Screen1.pa.yaml`, and `_EditorState.pa.yaml`.
Treat the app as empty when it has no screens with meaningful leaf controls. Containers
without leaf controls do not make the app non-empty.
- **Empty app:** read `${PLUGIN_ROOT}/references/CreateWorkflow.md` and follow it.
- **Existing app:** read `${PLUGIN_ROOT}/references/EditWorkflow.md` and follow it.
Do not load both workflow documents.
## Planned Build Handoff
CREATE and complex EDIT workflows return here after the planner finishes.
1. Read `[working directory]/canvas-app-plan.md` returned by the planner.
2. Verify its `## Requirement Coverage` table maps every concrete requested noun and
interaction to a visible affordance. Any approximation must be explicit and must not
use UI copy that claims the unavailable interaction is exact.
3. Verify its `## Action Contracts` table:
- Every requested or approved action has its own row and reachable entry point.
- Create, edit, delete, search, filter, approve, reject, period, and export behaviors
are not collapsed into vague combined rows.
- When review distinguishes approved and rejected outcomes, Approve and Reject/Decline
have separate contracts owned by the same eligible record surface.
- Every mutation names an observable bound result, not only a confirmation message.
- Every mutation declares a write set and receipt proof set. For create/edit, reject the
plan when any user-entered or user-selected write-set field is absent from the proof set.
- Supporting setup actions exist when required to exercise an explicitly requested
lifecycle, relationship, comparison, or ranking.
- Role-scoped management of all primary records includes separate visible select/edit/save
and remove/cancel paths, not only review or status controls.
- Create/edit contracts define required inputs, directly selectable finite choices,
stable identity, edit prepopulation, cancel/reset behavior, and post-save evidence.
- Every row names a precondition, source and stable identity, exact transition and
postcondition, observer reading that source, and visible evidence.
4. Verify its `## Functional Test Matrix`:
- Every Action Contract has at least one deterministic Given/When/Then success row.
- Every required invalid, blocked, empty, clear/reset, or boundary path has a row.
- Every `Then` names a source postcondition and an evidence surface that reads it.
- Local/mock scenarios use concrete seeded IDs and values. Filter scenarios include at
least two matching records and one non-matching record.
- EDIT scenarios cover existing behavior touched by changed sources, fields, controls,
or observer formulas.
5. Verify its `## Dispatch` table:
- Every row has `Action`, `Screen`, `Target File`, `YAML Key`, `Name Prefix`, and
`Screen Brief`.
- CREATE rows use `Create`; EDIT rows use `Modify` or `Create`.
- Target files and screen briefs are absolute paths under `[working directory]`.
- No two rows target the same file.
- No two rows share a `Name Prefix`.
- In CREATE mode the first row targets `[working directory]/Screen1.pa.yaml` with YAML key `Screen1`.
- `## Editor State Changes` exists and contains exact final order lists or `None`.
6. Confirm `[working directory]/canvas-app-shared.md` and every dispatch row's `Screen Brief` exists.
Verify each brief's assignment matches its dispatch row and includes every Action
Contract owned by that screen under `## Required Actions` and every scenario it
exercises under `## Functional Test Scenarios`.
7. In EDIT mode, apply the `### Before builders` group of `## App Changes` to
`[working directory]/App.pa.yaml` now. Screens bind to those collections, formulas and variables, and
compiling them against a stale `App.pa.yaml` produces a flood of false name errors.
8. Confirm the planner reported a clean `compile_canvas` for `[working directory]/App.pa.yaml`. If it
did not, compile now and resolve every `App`-level diagnostic before dispatching.
For EDIT mode, compile after applying the before-builder app changes and resolve
App-level diagnostics before dispatching.
9. Invoke `canvas-screen-builder` once per dispatch row, in waves of
**at most three**. Fire the wave's invocations together in one message, wait for that
wave to return, then dispatch the next.
Never dispatch more than three builders at once. Larger fan-outs have hung without
returning, and waves of three get you the first compile sooner, which is where systemic
defects surface.
If any pre-dispatch check fails, do not start builders. Re-invoke the planner with the
specific defects and repeat the checks on the corrected artifacts.
Pass each builder only:
```text
Action: [Create / Modify]
Screen: [logical screen name]
Target file: `[working directory]/[file].pa.yaml`
YAML screen key: [key from dispatch row]
Control name prefix: [prefix from dispatch row]
Shared plan: `[working directory]/canvas-app-shared.md`
Screen brief: `[working directory]/[file-base].screen-plan.md`
Plugin root: ${PLUGIN_ROOT}
```
The target file, YAML key, and name prefix are authoritative. Modify actions preserve the
key already present in the target file.
Compile after each wave returns, before dispatching the next. A systemic mistake in the
first wave is usually repeated in every later screen. Repair files that already exist in
place; only rows still waiting for dispatch receive corrected briefs.
A between-wave compile can report a `Navigate` target that belongs to a later wave as
unrecognized. Confirm it matches a remaining dispatch row and leave it in place.
After all builders finish:
- Check each builder's `Functional:` section before accepting its `QA:` line. It must
contain exactly one `PASS` trace per Required Action in that screen's brief, and each
trace must name the precondition, control event, source/stable-ID operation,
postcondition, and observer/evidence. A missing link, generic claim, or `BLOCKED` result
sends that screen back for targeted repair and a corrected trace; do not accept
checklist `PASS` as a substitute.
- Check each builder's `QA:` line. It must list an outcome for every check in
`${PLUGIN_ROOT}/references/QAChecks.md`. Treat these as unrun and send the screen back for self-QA
only — not a rebuild — before you compile:
- a missing or truncated `QA:` line, a line that omits any check listed in
`${PLUGIN_ROOT}/references/QAChecks.md`, or a bare fix count;
- an outcome that contradicts the screen structure — for example,
`QACHK-CROSS-AXIS-ALIGNMENT` is `N/A` despite AutoLayout children,
`QACHK-ACCESSIBLE-LABEL-MISSING` is `N/A` despite content or input controls,
`QACHK-LOW-CONTRAST-TEXT` is `N/A` despite a non-default coloured surface, or
`QACHK-ROOT-CONTAINMENT` is `PASS` while a responsive root has screen-level siblings;
- `QACHK-GALLERY-ROW-FITS-CONTENT` is `N/A` despite the screen containing a Gallery;
- `QACHK-ACTION-LABEL-FIT` is `PASS` while a multiword action directly under vertical
AutoLayout lacks `Width: =Parent.Width`;
`PASS` is valid after a complete inspection finds no defect; never reject it solely
because the screen has many controls.
This costs one cheap turn. The defects these checks catch — clipped headings, invisible
buttons, placeholder cards — are invisible to `compile_canvas`, so if you skip this the
app ships broken while reporting clean.
- A self-QA follow-up is not a rebuild or a screen-generation re-dispatch. Tell the
builder to inspect and repair the existing target file, then return the corrected
`QA:` line without regenerating the screen.
- Compare every repeated navigation block against `[working directory]/canvas-app-shared.md`: same
destination items, same order, no extra brand/label injected into one screen's nav,
and width formulas that fit the narrowest target. This is an app-wide check builders
cannot perform because each sees only one screen.
- Verify each `## Action Contracts` row end to end against the generated files: the entry
point is reachable, the named event is wired, and the observable result is visible
immediately after the action. For mutations, require an in-viewport receipt bound to the
returned record, changed stable ID, or deletion snapshot. Compare the handler formula,
declared write set, declared proof set, and receipt controls one-for-one. For create/edit,
every user-entered or user-selected field written by the handler needs a readable labeled
receipt binding. Navigation, a notification, hidden state, or a row somewhere in a longer
list cannot replace it. Compile success does not prove runtime usability.
- Execute every `## Functional Test Matrix` row symbolically against the final formulas.
Confirm the Given state makes the entry point eligible, the When event targets the
declared source and stable ID, the Then values follow from the operation, and the
evidence formula reads that post-state. Repair the owning file when any link depends on
an unstated assumption or a different source/field.
- For every primary-record list, verify each row or its immediately reachable detail renders
the canonical human-readable identity as full visible text. Avatar initials, icons,
record IDs, accessible labels, or evaluator inference cannot replace the identity.
- When Approve and Reject/Decline are paired contracts, verify every eligible pending record
exposes both decisions on the same row or the same immediately reachable detail at phone
width. Send the owning screen back when either decision is missing; never accept a
single-sided review queue as a density tradeoff.
- For every create/edit lifecycle, verify short static choices use radio buttons, visible
choice buttons, or a dropdown that commits by click or tap without typed filtering, then
trace create → bound mutation receipt → visible Edit → prepopulated form → stable-ID save
→ bound mutation receipt with updated values. At phone width, verify identity,
status, and required lifecycle actions remain visible or have an immediately visible
overflow/detail entry. Send only the owning screen back for self-QA when any link is
missing.
- Reject `QACHK-CARD-PLACEHOLDER` `PASS` when a ModernCard displays Title, Subtitle and
Description with `Height < 180`; send that screen back for self-QA.
- If a builder returns `Status: Blocked`, re-invoke the planner to correct that screen
brief, then rerun only the affected builder. Never ask a builder to guess missing
definitions.
- `Status: Blocked` is the **only** reason to rerun screen generation from a brief.
Compile diagnostics are not. Once a screen file exists you repair it in place with
targeted edits. Re-running generation rewrites the whole screen from scratch, discards
the fixes already applied, and produces a fresh crop of defects. That loop does not
converge.
- In EDIT mode, apply the `### After builders` group of `## App Changes` in
`[working directory]/canvas-app-plan.md` to `[working directory]/App.pa.yaml`. The `### Before builders` group was
already applied at pre-dispatch. If a group says `None`, do not edit the file for it.
- The orchestrator is the sole owner of EDIT changes to `[working directory]/App.pa.yaml`.
- Apply `## Editor State Changes` from `[working directory]/canvas-app-plan.md` to
`[working directory]/_EditorState.pa.yaml` after all builders finish. If it says `None`, leave the
file unchanged.
- Read `${PLUGIN_ROOT}/references/ValidationWorkflow.md` and follow it.
## Shared Invariants
1. Never guess control properties. Use `describe_control`; only use properties returned
for that exact control type.
2. Use exact RGBA values and shared variable names from approved plans.
3. **Control names are unique across the entire app, not per screen.** Two screens may
not both contain a control named `NavBar` or `btnBack`; the compiler rejects the
second with `An entity with name '...' already exists`. Every control a builder
writes uses the standard control-type abbreviation followed by that screen's assigned
name prefix, such as `conDiscNavBar` or `btnDetailBack`. This applies especially to UI
blocks repeated on many screens — nav bars, headers, toolbars, badges.
4. **Copy control creation keywords from `describe_control`.** `list_controls` provides
the name used to query `describe_control`; it is not the authority for authored YAML.
Copy the returned `Control:` value and every required `ComponentName`,
`ComponentLibraryUniqueName`, `Variant`, and `Layout` keyword verbatim. Never strip,
normalize, or reconstruct those values.
5. **Never invent an enum type name.** `describe_control` prints the exact name on the
`Enum name:` line of each enum property. Copy it verbatim. Enum names do not follow
from control names: `Badge.Appearance` is `BadgeCanvas.Appearance`, `Progress.Shape`
is `Progress.Shape`, and `ModernDropdown.Appearance` is just `Appearance`. An enum
**member** that starts with a digit must be quoted too — `DecimalPrecision.'1'`, never
`DecimalPrecision.1`, which fails with `Expected operator` and `Expected an operand`
rather than `Name isn't recognized`.
6. In CREATE mode, reuse `[working directory]/Screen1.pa.yaml` for the landing screen and set
`App.StartScreen` to `=Screen1`.
7. Never navigate from `App.OnStart` or the start screen's `OnVisible`.
8. Keep mock data compact: roughly 5-8 short rows per collection.
9. Builders own exactly one screen file. The planner owns CREATE-mode `App.pa.yaml`.
The orchestrator owns EDIT-mode `App.pa.yaml`.
10. Compile early and often. `App.pa.yaml` is validated before builders are dispatched,
and again as soon as the first builder returns. Never defer the first compile until
every file is written.
11. Do not report completion until the workspace compiles clean and the functional
conformance gate passes, or remaining compile and functional defects are explicitly
reported.