Build your own Shopify

You are building a production-ready software product named “Tinycart”, a deliberately focused alternative to Shopify. Build a complete, usable vertical slice—not a landing page, static mockup, or disconnected collection of components.

WORKING AGREEMENT
Before writing implementation code, produce a short technical plan that names the routes or pages, server actions or endpoints, data tables, important state transitions, authorization boundaries, background jobs, and external adapters. Resolve contradictions in favor of the narrow audience and non-goals below. Prefer a small, legible architecture over speculative abstraction, but do not omit persistence, validation, error handling, or tests.

PRODUCT BRIEF
Primary user: a maker selling fewer than 50 physical products in one country.
Primary outcome: publish a fast storefront, take payment through a hosted checkout, and fulfill simple orders.
Product principle: optimize the exact workflow below instead of copying the full breadth of Shopify. A first-time user should understand what to do from the interface itself, without a tour or documentation.

END-TO-END USER JOURNEYS
Implement all of these flows through the real interface and persistent data layer:
1. The merchant creates a product with two variants, uploads images, sets inventory and a flat shipping rate, previews the storefront, and publishes it.
2. A shopper searches the catalog, adds an in-stock variant to the cart, completes hosted checkout, and receives an order confirmation exactly once.
3. The merchant opens the paid order, marks it packing and shipped with tracking text, sends the update, then issues a full refund through the payment provider.

SCREENS AND INFORMATION ARCHITECTURE
Build these as coherent responsive views. Each screen must specify its primary action, secondary actions, visible status, validation feedback, empty state, loading or pending state, success confirmation, and recoverable failure state.
1. Product admin: product list, active state, variant matrix, prices, inventory, images, validation, preview, and publish actions.
2. Storefront and product: search, stock status, variant selection, quantity, image gallery, cart feedback, empty states, and accessible checkout path.
3. Cart and hosted checkout handoff: lines, quantities, shipping estimate, total, stock recheck, pending-payment state, return success, and cancelled checkout.
4. Orders: paid and fulfillment filters, customer and address, immutable lines and totals, timeline, packing, shipping, cancellation, refund, and notification state.

CORE CAPABILITIES
1. products with variants, price, inventory, images, and active state
2. searchable storefront, product page, cart, and stock-aware quantity controls
3. hosted checkout with shipping address and one flat-rate shipping rule
4. order dashboard with paid, packing, shipped, refunded, and cancelled states
5. customer confirmation and shipping emails

DETAILED BEHAVIOR AND BUSINESS RULES
Treat these as server-enforced product requirements, not interface suggestions:
1. Store money as integer minor units in one configured currency and snapshot product, variant, price, and shipping data onto order lines at checkout creation.
2. Reserve inventory transactionally for a bounded checkout window, release expired reservations idempotently, and never allow paid stock to fall below zero.
3. Treat verified payment webhooks as authoritative, deduplicate every provider event, and send confirmations only after the paid transition commits.
4. Enforce explicit paid, packing, shipped, cancelled, and refunded transitions with immutable history; execute refunds through the provider before recording success.

DATA MODEL AND LIFECYCLE
Design a small relational schema centered on Product, Variant, InventoryAdjustment, Cart, Order, OrderLine. Before implementing it, document:
1. Each table’s purpose, primary key, ownership or tenant boundary, timestamps, status fields, and important attributes.
2. Foreign keys, uniqueness constraints, check constraints, indexes needed by the named screens, and transaction boundaries for multi-record changes.
3. The allowed lifecycle or state transitions, who may trigger each transition, which transitions are terminal or reversible, and what audit history must remain immutable.
4. Archive, retention, and deletion behavior, including what happens to dependent records and external files.
5. Idempotency strategy for submissions, jobs, imports, notifications, webhooks, or retries where applicable.
Use migrations rather than ad-hoc schema creation. Store time instants consistently and retain named timezone context whenever local schedules or dates matter. Never rely on a counter, disabled button, or client-side check to preserve a business invariant.

USERS, AUTHENTICATION, AND PERMISSIONS
Implement only the roles required by the stated audience. Make the ownership and visibility model explicit before coding. Enforce authorization in every server-side query and mutation, including search, exports, attachments, live updates, and guessed URLs—not merely by hiding controls. Use secure session defaults, protect state-changing requests, and provide an understandable signed-out, expired-session, and forbidden state. Seed distinct users when multiple roles are required so permissions can be demonstrated and tested.

INTERACTION AND VISUAL DIRECTION
The product should feel fast, calm, focused, and credible rather than like a generic admin template. Use a clear visual hierarchy, restrained color, readable typography, generous hit targets, and consistent placement for primary actions. Start with server-rendered HTML and progressively enhance only the interactions that benefit from it. The core workflow must remain understandable if enhancement fails.

Start with server-rendered Astro pages and ordinary HTML forms. Use HTMX for form submissions, partial navigation, and server-driven updates, then Alpine.js only for small local browser state. The core workflow must remain understandable if either enhancement layer fails.

Design mobile layouts intentionally instead of simply stacking desktop panels. Support keyboard navigation, visible focus, semantic landmarks, explicit labels, useful page titles, reduced-motion preferences, and screen-reader announcements for asynchronous results. Never use color alone to communicate state. Destructive actions require clear scope and confirmation; safe repeated actions should be idempotent.

TECHNICAL DIRECTION
Build this version with the AHA stack: Astro for routing, layouts, and server-rendered pages; HTMX for interactions that benefit from HTML fragment responses; and Alpine.js for small, local interface state. Prefer Cloudflare D1 for relational persistence, R2 for object storage, Workers for server endpoints and scheduled work, Durable Objects only for coordinated real-time state, and Workflows or Queues for durable background jobs—but only when the product requirements call for them.

Keep domain rules in testable server-side modules instead of route handlers or UI components. Separate persistence, external providers, and background work behind small interfaces without building a framework. Prefer ordinary HTML forms and URLs for durable navigation; use optimistic interaction only when failure can be reconciled clearly.

The product brief currently identifies Astro, HTMX, D1 as capability context. Preserve any required native, browser-only, edge, storage, real-time, or background-processing capability through a narrow adapter appropriate to the selected framework. If the core workflow genuinely requires native or browser APIs, keep that runtime as the primary execution surface rather than simulating inaccessible capabilities or inventing an unnecessary web surface.

Integrate with Stripe Checkout and R2 object storage and transactional email. For every integration:
- List required environment variables in an .env.example without real secrets.
- Add a small adapter with timeouts, normalized errors, and a deterministic local fake or development path.
- Verify inbound signatures and deduplicate provider events where supported.
- Keep credentials server-side, encrypt long-lived provider tokens at rest, and redact secrets and sensitive payloads from logs.
- Define retry, backoff, and idempotency behavior for any side effect that can be repeated.

SECURITY AND PRIVACY
Keep card data entirely in hosted checkout, verify payment webhooks, reserve inventory transactionally, and make fulfillment state changes auditable.
Validate, normalize, and length-limit all untrusted input on the server. Escape rendered content by default, sanitize any intentionally accepted markup, rate-limit public or abuse-prone actions, and use private object storage plus short-lived authorized URLs for sensitive files. Collect the minimum personal data necessary for the named workflow. Document retention and deletion behavior. Add specific protections for the riskier surfaces in this app, such as uploads, redirects, outbound requests, email delivery, OAuth, webhooks, CSV import or export, and real-time connections.

ACCEPTANCE SCENARIOS
Automate these app-specific scenarios at the most appropriate level:
1. Given one unit remains and two shoppers attempt checkout, at most one reservation succeeds and the other receives a recoverable out-of-stock state.
2. Given the same paid webhook is delivered three times, one order becomes paid and one confirmation is sent.
3. Given a refund provider timeout, the order is not labeled refunded until reconciliation confirms the external result.

TESTING
Add focused unit tests for state transitions, authorization predicates, normalization, date or money calculations, and other risky domain rules. Add integration tests for persistence constraints and each external adapter’s success, timeout, retry, and rejection paths. Add at least one browser-level test for every end-to-end journey above, including one small-screen viewport. Tests must use isolated data and run through a documented single command.

OPERATIONS AND FAILURE RECOVERY
Add structured server logs with request, job, or event correlation IDs but no secrets or unnecessarily sensitive data. Make failures actionable in both the interface and logs. Background work must expose pending, succeeded, failed, and retrying states where relevant; do not silently swallow errors. Include safe database migration and rollback guidance, seed data, backup and restore notes, external-data cleanup behavior, and a basic health or diagnostic path appropriate to the stack.

DELIVERABLES
Ship the working application, migrations, representative seed data, tests, .env.example, and a concise README. The README must cover prerequisites, local setup, environment variables, migrations, seed and test commands, deployment, integration setup, backup and restore, security decisions, and known limitations. Seed data should exercise the happy path plus at least one empty, failed, overdue, expired, archived, or permission-restricted state relevant to the product.

DEFINITION OF DONE
The app is complete when a fresh developer can follow the README, create and migrate the database, run the app, sign in as each relevant role, complete every named journey using real persisted data, refresh without losing state, recover from common failures, and use the core interface on phone and desktop. All acceptance scenarios pass, permission boundaries are covered by tests, and no core screen is left as a placeholder.

NON-GOALS
Do not calculate complex tax, run a marketplace, support subscriptions, multiple currencies, point of sale, returns automation, or carrier integrations.

You are building a production-ready software product named “Tinycart”, a deliberately focused alternative to Shopify. Build a complete, usable vertical slice—not a landing page, static mockup, or disconnected collection of components.

WORKING AGREEMENT
Before writing implementation code, produce a short technical plan that names the routes or pages, server actions or endpoints, data tables, important state transitions, authorization boundaries, background jobs, and external adapters. Resolve contradictions in favor of the narrow audience and non-goals below. Prefer a small, legible architecture over speculative abstraction, but do not omit persistence, validation, error handling, or tests.

PRODUCT BRIEF
Primary user: a maker selling fewer than 50 physical products in one country.
Primary outcome: publish a fast storefront, take payment through a hosted checkout, and fulfill simple orders.
Product principle: optimize the exact workflow below instead of copying the full breadth of Shopify. A first-time user should understand what to do from the interface itself, without a tour or documentation.

END-TO-END USER JOURNEYS
Implement all of these flows through the real interface and persistent data layer:
1. The merchant creates a product with two variants, uploads images, sets inventory and a flat shipping rate, previews the storefront, and publishes it.
2. A shopper searches the catalog, adds an in-stock variant to the cart, completes hosted checkout, and receives an order confirmation exactly once.
3. The merchant opens the paid order, marks it packing and shipped with tracking text, sends the update, then issues a full refund through the payment provider.

SCREENS AND INFORMATION ARCHITECTURE
Build these as coherent responsive views. Each screen must specify its primary action, secondary actions, visible status, validation feedback, empty state, loading or pending state, success confirmation, and recoverable failure state.
1. Product admin: product list, active state, variant matrix, prices, inventory, images, validation, preview, and publish actions.
2. Storefront and product: search, stock status, variant selection, quantity, image gallery, cart feedback, empty states, and accessible checkout path.
3. Cart and hosted checkout handoff: lines, quantities, shipping estimate, total, stock recheck, pending-payment state, return success, and cancelled checkout.
4. Orders: paid and fulfillment filters, customer and address, immutable lines and totals, timeline, packing, shipping, cancellation, refund, and notification state.

CORE CAPABILITIES
1. products with variants, price, inventory, images, and active state
2. searchable storefront, product page, cart, and stock-aware quantity controls
3. hosted checkout with shipping address and one flat-rate shipping rule
4. order dashboard with paid, packing, shipped, refunded, and cancelled states
5. customer confirmation and shipping emails

DETAILED BEHAVIOR AND BUSINESS RULES
Treat these as server-enforced product requirements, not interface suggestions:
1. Store money as integer minor units in one configured currency and snapshot product, variant, price, and shipping data onto order lines at checkout creation.
2. Reserve inventory transactionally for a bounded checkout window, release expired reservations idempotently, and never allow paid stock to fall below zero.
3. Treat verified payment webhooks as authoritative, deduplicate every provider event, and send confirmations only after the paid transition commits.
4. Enforce explicit paid, packing, shipped, cancelled, and refunded transitions with immutable history; execute refunds through the provider before recording success.

DATA MODEL AND LIFECYCLE
Design a small relational schema centered on Product, Variant, InventoryAdjustment, Cart, Order, OrderLine. Before implementing it, document:
1. Each table’s purpose, primary key, ownership or tenant boundary, timestamps, status fields, and important attributes.
2. Foreign keys, uniqueness constraints, check constraints, indexes needed by the named screens, and transaction boundaries for multi-record changes.
3. The allowed lifecycle or state transitions, who may trigger each transition, which transitions are terminal or reversible, and what audit history must remain immutable.
4. Archive, retention, and deletion behavior, including what happens to dependent records and external files.
5. Idempotency strategy for submissions, jobs, imports, notifications, webhooks, or retries where applicable.
Use migrations rather than ad-hoc schema creation. Store time instants consistently and retain named timezone context whenever local schedules or dates matter. Never rely on a counter, disabled button, or client-side check to preserve a business invariant.

USERS, AUTHENTICATION, AND PERMISSIONS
Implement only the roles required by the stated audience. Make the ownership and visibility model explicit before coding. Enforce authorization in every server-side query and mutation, including search, exports, attachments, live updates, and guessed URLs—not merely by hiding controls. Use secure session defaults, protect state-changing requests, and provide an understandable signed-out, expired-session, and forbidden state. Seed distinct users when multiple roles are required so permissions can be demonstrated and tested.

INTERACTION AND VISUAL DIRECTION
The product should feel fast, calm, focused, and credible rather than like a generic admin template. Use a clear visual hierarchy, restrained color, readable typography, generous hit targets, and consistent placement for primary actions. Start with server-rendered HTML and progressively enhance only the interactions that benefit from it. The core workflow must remain understandable if enhancement fails.

Render with React Server Components by default. Use Server Actions for authenticated form mutations and add Client Components only for interactions that genuinely require browser state, browser APIs, drag-and-drop, or live updates. The core workflow must remain understandable before client-side JavaScript finishes loading.

Design mobile layouts intentionally instead of simply stacking desktop panels. Support keyboard navigation, visible focus, semantic landmarks, explicit labels, useful page titles, reduced-motion preferences, and screen-reader announcements for asynchronous results. Never use color alone to communicate state. Destructive actions require clear scope and confirmation; safe repeated actions should be idempotent.

TECHNICAL DIRECTION
Build this version with Next.js, the App Router, and TypeScript. Use Server Components by default, Server Actions for authenticated mutations, and Route Handlers for public APIs, OAuth callbacks, webhooks, feeds, uploads, and downloads. Use PostgreSQL through Drizzle ORM with versioned migrations and an isolated test database. Access S3-compatible object storage through a server-only adapter, and run slow or retryable work in a real job or workflow system instead of the request lifecycle.

Keep domain rules in testable server-side modules instead of route handlers or UI components. Separate persistence, external providers, and background work behind small interfaces without building a framework. Prefer ordinary HTML forms and URLs for durable navigation; use optimistic interaction only when failure can be reconciled clearly.

The product brief currently identifies Astro, HTMX, D1 as capability context. Preserve any required native, browser-only, edge, storage, real-time, or background-processing capability through a narrow adapter appropriate to the selected framework. If the core workflow genuinely requires native or browser APIs, keep that runtime as the primary execution surface rather than simulating inaccessible capabilities or inventing an unnecessary web surface.

Integrate with Stripe Checkout and R2 object storage and transactional email. For every integration:
- List required environment variables in an .env.example without real secrets.
- Add a small adapter with timeouts, normalized errors, and a deterministic local fake or development path.
- Verify inbound signatures and deduplicate provider events where supported.
- Keep credentials server-side, encrypt long-lived provider tokens at rest, and redact secrets and sensitive payloads from logs.
- Define retry, backoff, and idempotency behavior for any side effect that can be repeated.

SECURITY AND PRIVACY
Keep card data entirely in hosted checkout, verify payment webhooks, reserve inventory transactionally, and make fulfillment state changes auditable.
Validate, normalize, and length-limit all untrusted input on the server. Escape rendered content by default, sanitize any intentionally accepted markup, rate-limit public or abuse-prone actions, and use private object storage plus short-lived authorized URLs for sensitive files. Collect the minimum personal data necessary for the named workflow. Document retention and deletion behavior. Add specific protections for the riskier surfaces in this app, such as uploads, redirects, outbound requests, email delivery, OAuth, webhooks, CSV import or export, and real-time connections.

ACCEPTANCE SCENARIOS
Automate these app-specific scenarios at the most appropriate level:
1. Given one unit remains and two shoppers attempt checkout, at most one reservation succeeds and the other receives a recoverable out-of-stock state.
2. Given the same paid webhook is delivered three times, one order becomes paid and one confirmation is sent.
3. Given a refund provider timeout, the order is not labeled refunded until reconciliation confirms the external result.

TESTING
Add focused unit tests for state transitions, authorization predicates, normalization, date or money calculations, and other risky domain rules. Add integration tests for persistence constraints and each external adapter’s success, timeout, retry, and rejection paths. Add at least one browser-level test for every end-to-end journey above, including one small-screen viewport. Tests must use isolated data and run through a documented single command.

OPERATIONS AND FAILURE RECOVERY
Add structured server logs with request, job, or event correlation IDs but no secrets or unnecessarily sensitive data. Make failures actionable in both the interface and logs. Background work must expose pending, succeeded, failed, and retrying states where relevant; do not silently swallow errors. Include safe database migration and rollback guidance, seed data, backup and restore notes, external-data cleanup behavior, and a basic health or diagnostic path appropriate to the stack.

DELIVERABLES
Ship the working application, migrations, representative seed data, tests, .env.example, and a concise README. The README must cover prerequisites, local setup, environment variables, migrations, seed and test commands, deployment, integration setup, backup and restore, security decisions, and known limitations. Seed data should exercise the happy path plus at least one empty, failed, overdue, expired, archived, or permission-restricted state relevant to the product.

DEFINITION OF DONE
The app is complete when a fresh developer can follow the README, create and migrate the database, run the app, sign in as each relevant role, complete every named journey using real persisted data, refresh without losing state, recover from common failures, and use the core interface on phone and desktop. All acceptance scenarios pass, permission boundaries are covered by tests, and no core screen is left as a placeholder.

NON-GOALS
Do not calculate complex tax, run a marketplace, support subscriptions, multiple currencies, point of sale, returns automation, or carrier integrations.

You are building a production-ready software product named “Tinycart”, a deliberately focused alternative to Shopify. Build a complete, usable vertical slice—not a landing page, static mockup, or disconnected collection of components.

WORKING AGREEMENT
Before writing implementation code, produce a short technical plan that names the routes or pages, server actions or endpoints, data tables, important state transitions, authorization boundaries, background jobs, and external adapters. Resolve contradictions in favor of the narrow audience and non-goals below. Prefer a small, legible architecture over speculative abstraction, but do not omit persistence, validation, error handling, or tests.

PRODUCT BRIEF
Primary user: a maker selling fewer than 50 physical products in one country.
Primary outcome: publish a fast storefront, take payment through a hosted checkout, and fulfill simple orders.
Product principle: optimize the exact workflow below instead of copying the full breadth of Shopify. A first-time user should understand what to do from the interface itself, without a tour or documentation.

END-TO-END USER JOURNEYS
Implement all of these flows through the real interface and persistent data layer:
1. The merchant creates a product with two variants, uploads images, sets inventory and a flat shipping rate, previews the storefront, and publishes it.
2. A shopper searches the catalog, adds an in-stock variant to the cart, completes hosted checkout, and receives an order confirmation exactly once.
3. The merchant opens the paid order, marks it packing and shipped with tracking text, sends the update, then issues a full refund through the payment provider.

SCREENS AND INFORMATION ARCHITECTURE
Build these as coherent responsive views. Each screen must specify its primary action, secondary actions, visible status, validation feedback, empty state, loading or pending state, success confirmation, and recoverable failure state.
1. Product admin: product list, active state, variant matrix, prices, inventory, images, validation, preview, and publish actions.
2. Storefront and product: search, stock status, variant selection, quantity, image gallery, cart feedback, empty states, and accessible checkout path.
3. Cart and hosted checkout handoff: lines, quantities, shipping estimate, total, stock recheck, pending-payment state, return success, and cancelled checkout.
4. Orders: paid and fulfillment filters, customer and address, immutable lines and totals, timeline, packing, shipping, cancellation, refund, and notification state.

CORE CAPABILITIES
1. products with variants, price, inventory, images, and active state
2. searchable storefront, product page, cart, and stock-aware quantity controls
3. hosted checkout with shipping address and one flat-rate shipping rule
4. order dashboard with paid, packing, shipped, refunded, and cancelled states
5. customer confirmation and shipping emails

DETAILED BEHAVIOR AND BUSINESS RULES
Treat these as server-enforced product requirements, not interface suggestions:
1. Store money as integer minor units in one configured currency and snapshot product, variant, price, and shipping data onto order lines at checkout creation.
2. Reserve inventory transactionally for a bounded checkout window, release expired reservations idempotently, and never allow paid stock to fall below zero.
3. Treat verified payment webhooks as authoritative, deduplicate every provider event, and send confirmations only after the paid transition commits.
4. Enforce explicit paid, packing, shipped, cancelled, and refunded transitions with immutable history; execute refunds through the provider before recording success.

DATA MODEL AND LIFECYCLE
Design a small relational schema centered on Product, Variant, InventoryAdjustment, Cart, Order, OrderLine. Before implementing it, document:
1. Each table’s purpose, primary key, ownership or tenant boundary, timestamps, status fields, and important attributes.
2. Foreign keys, uniqueness constraints, check constraints, indexes needed by the named screens, and transaction boundaries for multi-record changes.
3. The allowed lifecycle or state transitions, who may trigger each transition, which transitions are terminal or reversible, and what audit history must remain immutable.
4. Archive, retention, and deletion behavior, including what happens to dependent records and external files.
5. Idempotency strategy for submissions, jobs, imports, notifications, webhooks, or retries where applicable.
Use migrations rather than ad-hoc schema creation. Store time instants consistently and retain named timezone context whenever local schedules or dates matter. Never rely on a counter, disabled button, or client-side check to preserve a business invariant.

USERS, AUTHENTICATION, AND PERMISSIONS
Implement only the roles required by the stated audience. Make the ownership and visibility model explicit before coding. Enforce authorization in every server-side query and mutation, including search, exports, attachments, live updates, and guessed URLs—not merely by hiding controls. Use secure session defaults, protect state-changing requests, and provide an understandable signed-out, expired-session, and forbidden state. Seed distinct users when multiple roles are required so permissions can be demonstrated and tested.

INTERACTION AND VISUAL DIRECTION
The product should feel fast, calm, focused, and credible rather than like a generic admin template. Use a clear visual hierarchy, restrained color, readable typography, generous hit targets, and consistent placement for primary actions. Start with server-rendered HTML and progressively enhance only the interactions that benefit from it. The core workflow must remain understandable if enhancement fails.

Start with server-rendered Blade views and ordinary forms. Use Livewire for focused server-driven interactions and Alpine.js only for small local interface state. The core workflow must remain understandable without relying on a client-side application shell.

Design mobile layouts intentionally instead of simply stacking desktop panels. Support keyboard navigation, visible focus, semantic landmarks, explicit labels, useful page titles, reduced-motion preferences, and screen-reader announcements for asynchronous results. Never use color alone to communicate state. Destructive actions require clear scope and confirmation; safe repeated actions should be idempotent.

TECHNICAL DIRECTION
Build this version with Laravel, PHP, Blade, Livewire, and Alpine.js. Use controllers and Blade forms for durable navigation, Livewire for focused interactions, Form Requests for validation, Policies and Gates for authorization, and small application actions or services for domain transitions. Use Eloquent with migrations, database constraints, and transactions; Laravel Storage for private S3-compatible files; queued Jobs for retryable work; the Scheduler for recurring work; and Notifications or Mail for email.

Keep domain rules in testable server-side modules instead of route handlers or UI components. Separate persistence, external providers, and background work behind small interfaces without building a framework. Prefer ordinary HTML forms and URLs for durable navigation; use optimistic interaction only when failure can be reconciled clearly.

The product brief currently identifies Astro, HTMX, D1 as capability context. Preserve any required native, browser-only, edge, storage, real-time, or background-processing capability through a narrow adapter appropriate to the selected framework. If the core workflow genuinely requires native or browser APIs, keep that runtime as the primary execution surface rather than simulating inaccessible capabilities or inventing an unnecessary web surface.

Integrate with Stripe Checkout and R2 object storage and transactional email. For every integration:
- List required environment variables in an .env.example without real secrets.
- Add a small adapter with timeouts, normalized errors, and a deterministic local fake or development path.
- Verify inbound signatures and deduplicate provider events where supported.
- Keep credentials server-side, encrypt long-lived provider tokens at rest, and redact secrets and sensitive payloads from logs.
- Define retry, backoff, and idempotency behavior for any side effect that can be repeated.

SECURITY AND PRIVACY
Keep card data entirely in hosted checkout, verify payment webhooks, reserve inventory transactionally, and make fulfillment state changes auditable.
Validate, normalize, and length-limit all untrusted input on the server. Escape rendered content by default, sanitize any intentionally accepted markup, rate-limit public or abuse-prone actions, and use private object storage plus short-lived authorized URLs for sensitive files. Collect the minimum personal data necessary for the named workflow. Document retention and deletion behavior. Add specific protections for the riskier surfaces in this app, such as uploads, redirects, outbound requests, email delivery, OAuth, webhooks, CSV import or export, and real-time connections.

ACCEPTANCE SCENARIOS
Automate these app-specific scenarios at the most appropriate level:
1. Given one unit remains and two shoppers attempt checkout, at most one reservation succeeds and the other receives a recoverable out-of-stock state.
2. Given the same paid webhook is delivered three times, one order becomes paid and one confirmation is sent.
3. Given a refund provider timeout, the order is not labeled refunded until reconciliation confirms the external result.

TESTING
Add focused unit tests for state transitions, authorization predicates, normalization, date or money calculations, and other risky domain rules. Add integration tests for persistence constraints and each external adapter’s success, timeout, retry, and rejection paths. Add at least one browser-level test for every end-to-end journey above, including one small-screen viewport. Tests must use isolated data and run through a documented single command.

OPERATIONS AND FAILURE RECOVERY
Add structured server logs with request, job, or event correlation IDs but no secrets or unnecessarily sensitive data. Make failures actionable in both the interface and logs. Background work must expose pending, succeeded, failed, and retrying states where relevant; do not silently swallow errors. Include safe database migration and rollback guidance, seed data, backup and restore notes, external-data cleanup behavior, and a basic health or diagnostic path appropriate to the stack.

DELIVERABLES
Ship the working application, migrations, representative seed data, tests, .env.example, and a concise README. The README must cover prerequisites, local setup, environment variables, migrations, seed and test commands, deployment, integration setup, backup and restore, security decisions, and known limitations. Seed data should exercise the happy path plus at least one empty, failed, overdue, expired, archived, or permission-restricted state relevant to the product.

DEFINITION OF DONE
The app is complete when a fresh developer can follow the README, create and migrate the database, run the app, sign in as each relevant role, complete every named journey using real persisted data, refresh without losing state, recover from common failures, and use the core interface on phone and desktop. All acceptance scenarios pass, permission boundaries are covered by tests, and no core screen is left as a placeholder.

NON-GOALS
Do not calculate complex tax, run a marketplace, support subscriptions, multiple currencies, point of sale, returns automation, or carrier integrations.

You are building a production-ready software product named “Tinycart”, a deliberately focused alternative to Shopify. Build a complete, usable vertical slice—not a landing page, static mockup, or disconnected collection of components.

WORKING AGREEMENT
Before writing implementation code, produce a short technical plan that names the routes or pages, server actions or endpoints, data tables, important state transitions, authorization boundaries, background jobs, and external adapters. Resolve contradictions in favor of the narrow audience and non-goals below. Prefer a small, legible architecture over speculative abstraction, but do not omit persistence, validation, error handling, or tests.

PRODUCT BRIEF
Primary user: a maker selling fewer than 50 physical products in one country.
Primary outcome: publish a fast storefront, take payment through a hosted checkout, and fulfill simple orders.
Product principle: optimize the exact workflow below instead of copying the full breadth of Shopify. A first-time user should understand what to do from the interface itself, without a tour or documentation.

END-TO-END USER JOURNEYS
Implement all of these flows through the real interface and persistent data layer:
1. The merchant creates a product with two variants, uploads images, sets inventory and a flat shipping rate, previews the storefront, and publishes it.
2. A shopper searches the catalog, adds an in-stock variant to the cart, completes hosted checkout, and receives an order confirmation exactly once.
3. The merchant opens the paid order, marks it packing and shipped with tracking text, sends the update, then issues a full refund through the payment provider.

SCREENS AND INFORMATION ARCHITECTURE
Build these as coherent responsive views. Each screen must specify its primary action, secondary actions, visible status, validation feedback, empty state, loading or pending state, success confirmation, and recoverable failure state.
1. Product admin: product list, active state, variant matrix, prices, inventory, images, validation, preview, and publish actions.
2. Storefront and product: search, stock status, variant selection, quantity, image gallery, cart feedback, empty states, and accessible checkout path.
3. Cart and hosted checkout handoff: lines, quantities, shipping estimate, total, stock recheck, pending-payment state, return success, and cancelled checkout.
4. Orders: paid and fulfillment filters, customer and address, immutable lines and totals, timeline, packing, shipping, cancellation, refund, and notification state.

CORE CAPABILITIES
1. products with variants, price, inventory, images, and active state
2. searchable storefront, product page, cart, and stock-aware quantity controls
3. hosted checkout with shipping address and one flat-rate shipping rule
4. order dashboard with paid, packing, shipped, refunded, and cancelled states
5. customer confirmation and shipping emails

DETAILED BEHAVIOR AND BUSINESS RULES
Treat these as server-enforced product requirements, not interface suggestions:
1. Store money as integer minor units in one configured currency and snapshot product, variant, price, and shipping data onto order lines at checkout creation.
2. Reserve inventory transactionally for a bounded checkout window, release expired reservations idempotently, and never allow paid stock to fall below zero.
3. Treat verified payment webhooks as authoritative, deduplicate every provider event, and send confirmations only after the paid transition commits.
4. Enforce explicit paid, packing, shipped, cancelled, and refunded transitions with immutable history; execute refunds through the provider before recording success.

DATA MODEL AND LIFECYCLE
Design a small relational schema centered on Product, Variant, InventoryAdjustment, Cart, Order, OrderLine. Before implementing it, document:
1. Each table’s purpose, primary key, ownership or tenant boundary, timestamps, status fields, and important attributes.
2. Foreign keys, uniqueness constraints, check constraints, indexes needed by the named screens, and transaction boundaries for multi-record changes.
3. The allowed lifecycle or state transitions, who may trigger each transition, which transitions are terminal or reversible, and what audit history must remain immutable.
4. Archive, retention, and deletion behavior, including what happens to dependent records and external files.
5. Idempotency strategy for submissions, jobs, imports, notifications, webhooks, or retries where applicable.
Use migrations rather than ad-hoc schema creation. Store time instants consistently and retain named timezone context whenever local schedules or dates matter. Never rely on a counter, disabled button, or client-side check to preserve a business invariant.

USERS, AUTHENTICATION, AND PERMISSIONS
Implement only the roles required by the stated audience. Make the ownership and visibility model explicit before coding. Enforce authorization in every server-side query and mutation, including search, exports, attachments, live updates, and guessed URLs—not merely by hiding controls. Use secure session defaults, protect state-changing requests, and provide an understandable signed-out, expired-session, and forbidden state. Seed distinct users when multiple roles are required so permissions can be demonstrated and tested.

INTERACTION AND VISUAL DIRECTION
The product should feel fast, calm, focused, and credible rather than like a generic admin template. Use a clear visual hierarchy, restrained color, readable typography, generous hit targets, and consistent placement for primary actions. Start with server-rendered HTML and progressively enhance only the interactions that benefit from it. The core workflow must remain understandable if enhancement fails.

Start with server-rendered Rails views and ordinary forms. Use Turbo for navigation, submissions, and server-driven updates, then Stimulus only for small browser-side behavior. Do not turn the product into a client-side SPA, and keep the core workflow usable when enhancement fails.

Design mobile layouts intentionally instead of simply stacking desktop panels. Support keyboard navigation, visible focus, semantic landmarks, explicit labels, useful page titles, reduced-motion preferences, and screen-reader announcements for asynchronous results. Never use color alone to communicate state. Destructive actions require clear scope and confirmation; safe repeated actions should be idempotent.

TECHNICAL DIRECTION
Build this version with Ruby on Rails and Hotwire: Turbo for navigation, form submissions, and server-driven updates, and Stimulus for small browser-side behavior. Use RESTful controllers with strong parameters and explicit authorization, with domain transitions in testable models or small application services. Use Active Record migrations plus database-level constraints and transactions; Active Storage with an S3-compatible service for private files; Active Job with a durable queue backend for retryable work; Action Mailer for email; and Action Cable only when live updates are required.

Keep domain rules in testable server-side modules instead of route handlers or UI components. Separate persistence, external providers, and background work behind small interfaces without building a framework. Prefer ordinary HTML forms and URLs for durable navigation; use optimistic interaction only when failure can be reconciled clearly.

The product brief currently identifies Astro, HTMX, D1 as capability context. Preserve any required native, browser-only, edge, storage, real-time, or background-processing capability through a narrow adapter appropriate to the selected framework. If the core workflow genuinely requires native or browser APIs, keep that runtime as the primary execution surface rather than simulating inaccessible capabilities or inventing an unnecessary web surface.

Integrate with Stripe Checkout and R2 object storage and transactional email. For every integration:
- List required environment variables in an .env.example without real secrets.
- Add a small adapter with timeouts, normalized errors, and a deterministic local fake or development path.
- Verify inbound signatures and deduplicate provider events where supported.
- Keep credentials server-side, encrypt long-lived provider tokens at rest, and redact secrets and sensitive payloads from logs.
- Define retry, backoff, and idempotency behavior for any side effect that can be repeated.

SECURITY AND PRIVACY
Keep card data entirely in hosted checkout, verify payment webhooks, reserve inventory transactionally, and make fulfillment state changes auditable.
Validate, normalize, and length-limit all untrusted input on the server. Escape rendered content by default, sanitize any intentionally accepted markup, rate-limit public or abuse-prone actions, and use private object storage plus short-lived authorized URLs for sensitive files. Collect the minimum personal data necessary for the named workflow. Document retention and deletion behavior. Add specific protections for the riskier surfaces in this app, such as uploads, redirects, outbound requests, email delivery, OAuth, webhooks, CSV import or export, and real-time connections.

ACCEPTANCE SCENARIOS
Automate these app-specific scenarios at the most appropriate level:
1. Given one unit remains and two shoppers attempt checkout, at most one reservation succeeds and the other receives a recoverable out-of-stock state.
2. Given the same paid webhook is delivered three times, one order becomes paid and one confirmation is sent.
3. Given a refund provider timeout, the order is not labeled refunded until reconciliation confirms the external result.

TESTING
Add focused unit tests for state transitions, authorization predicates, normalization, date or money calculations, and other risky domain rules. Add integration tests for persistence constraints and each external adapter’s success, timeout, retry, and rejection paths. Add at least one browser-level test for every end-to-end journey above, including one small-screen viewport. Tests must use isolated data and run through a documented single command.

OPERATIONS AND FAILURE RECOVERY
Add structured server logs with request, job, or event correlation IDs but no secrets or unnecessarily sensitive data. Make failures actionable in both the interface and logs. Background work must expose pending, succeeded, failed, and retrying states where relevant; do not silently swallow errors. Include safe database migration and rollback guidance, seed data, backup and restore notes, external-data cleanup behavior, and a basic health or diagnostic path appropriate to the stack.

DELIVERABLES
Ship the working application, migrations, representative seed data, tests, .env.example, and a concise README. The README must cover prerequisites, local setup, environment variables, migrations, seed and test commands, deployment, integration setup, backup and restore, security decisions, and known limitations. Seed data should exercise the happy path plus at least one empty, failed, overdue, expired, archived, or permission-restricted state relevant to the product.

DEFINITION OF DONE
The app is complete when a fresh developer can follow the README, create and migrate the database, run the app, sign in as each relevant role, complete every named journey using real persisted data, refresh without losing state, recover from common failures, and use the core interface on phone and desktop. All acceptance scenarios pass, permission boundaries are covered by tests, and no core screen is left as a placeholder.

NON-GOALS
Do not calculate complex tax, run a marketplace, support subscriptions, multiple currencies, point of sale, returns automation, or carrier integrations.