Build your own TinyPNG Pro

You are building a production-ready software product named “Squooshbox”, a deliberately focused alternative to TinyPNG Pro. 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 designer compressing batches of web images.
Primary outcome: compress common image formats locally and make the savings obvious.
Product principle: optimize the exact workflow below instead of copying the full breadth of TinyPNG Pro. 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 user drops a mixed batch of images, watches each file validate and compress locally, then compares original and result sizes.
2. The user selects one image, adjusts output format and quality, examines a split preview, and applies those settings to selected files.
3. The user downloads one optimized image or a ZIP with predictable names, while unsupported and failed files remain clearly identified.

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. Workspace: prominent drop zone, file picker, privacy statement, batch list, overall bytes saved, clear-all, and download-all controls.
2. Image row: thumbnail, source and output format, dimensions, original bytes, result bytes, savings percentage, state, and remove action.
3. Inspector: zoomable before-and-after split view, format, quality, resize controls, metadata policy, and live recompression indicator.
4. Completion state: summary by success and failure, ZIP size, filenames, and a reminder that refreshing discards all local work.

CORE CAPABILITIES
1. drag-and-drop or file picker for multiple images
2. quality controls with sensible per-format defaults
3. before and after dimensions, bytes, and percentage saved
4. side-by-side preview for the selected image
5. download one file or all results as a ZIP

DETAILED BEHAVIOR AND BUSINESS RULES
Treat these as server-enforced product requirements, not interface suggestions:
1. Process files entirely in the browser, revoke object URLs after use, and never send image bytes to analytics or a server.
2. Preserve aspect ratio by default, prevent accidental upscaling, enforce pixel and memory limits, and explain unsupported browser capabilities.
3. Never replace the original file in place; produce a deterministic suffix and resolve duplicate output names inside ZIP downloads.
4. Run a bounded number of compression jobs concurrently so a large batch keeps the interface responsive and can be canceled.

DATA MODEL AND LIFECYCLE
Design a small relational schema centered on local ProcessingJob and ImageResult objects only. 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, Alpine, Browser API 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 browser Canvas and WebCodecs when supported. 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
Process images in the browser by default so originals never leave the device.
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. A valid JPEG batch finishes without network requests and download-all returns a ZIP containing one result for each successful source.
2. An oversized or unsupported image fails independently with a clear reason while the rest of the batch continues processing.
3. Changing quality updates the selected preview and byte estimate, but does not affect other files until apply-to-selected is confirmed.

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 add accounts, cloud storage, billing, or an image CDN.

You are building a production-ready software product named “Squooshbox”, a deliberately focused alternative to TinyPNG Pro. 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 designer compressing batches of web images.
Primary outcome: compress common image formats locally and make the savings obvious.
Product principle: optimize the exact workflow below instead of copying the full breadth of TinyPNG Pro. 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 user drops a mixed batch of images, watches each file validate and compress locally, then compares original and result sizes.
2. The user selects one image, adjusts output format and quality, examines a split preview, and applies those settings to selected files.
3. The user downloads one optimized image or a ZIP with predictable names, while unsupported and failed files remain clearly identified.

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. Workspace: prominent drop zone, file picker, privacy statement, batch list, overall bytes saved, clear-all, and download-all controls.
2. Image row: thumbnail, source and output format, dimensions, original bytes, result bytes, savings percentage, state, and remove action.
3. Inspector: zoomable before-and-after split view, format, quality, resize controls, metadata policy, and live recompression indicator.
4. Completion state: summary by success and failure, ZIP size, filenames, and a reminder that refreshing discards all local work.

CORE CAPABILITIES
1. drag-and-drop or file picker for multiple images
2. quality controls with sensible per-format defaults
3. before and after dimensions, bytes, and percentage saved
4. side-by-side preview for the selected image
5. download one file or all results as a ZIP

DETAILED BEHAVIOR AND BUSINESS RULES
Treat these as server-enforced product requirements, not interface suggestions:
1. Process files entirely in the browser, revoke object URLs after use, and never send image bytes to analytics or a server.
2. Preserve aspect ratio by default, prevent accidental upscaling, enforce pixel and memory limits, and explain unsupported browser capabilities.
3. Never replace the original file in place; produce a deterministic suffix and resolve duplicate output names inside ZIP downloads.
4. Run a bounded number of compression jobs concurrently so a large batch keeps the interface responsive and can be canceled.

DATA MODEL AND LIFECYCLE
Design a small relational schema centered on local ProcessingJob and ImageResult objects only. 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, Alpine, Browser API 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 browser Canvas and WebCodecs when supported. 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
Process images in the browser by default so originals never leave the device.
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. A valid JPEG batch finishes without network requests and download-all returns a ZIP containing one result for each successful source.
2. An oversized or unsupported image fails independently with a clear reason while the rest of the batch continues processing.
3. Changing quality updates the selected preview and byte estimate, but does not affect other files until apply-to-selected is confirmed.

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 add accounts, cloud storage, billing, or an image CDN.

You are building a production-ready software product named “Squooshbox”, a deliberately focused alternative to TinyPNG Pro. 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 designer compressing batches of web images.
Primary outcome: compress common image formats locally and make the savings obvious.
Product principle: optimize the exact workflow below instead of copying the full breadth of TinyPNG Pro. 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 user drops a mixed batch of images, watches each file validate and compress locally, then compares original and result sizes.
2. The user selects one image, adjusts output format and quality, examines a split preview, and applies those settings to selected files.
3. The user downloads one optimized image or a ZIP with predictable names, while unsupported and failed files remain clearly identified.

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. Workspace: prominent drop zone, file picker, privacy statement, batch list, overall bytes saved, clear-all, and download-all controls.
2. Image row: thumbnail, source and output format, dimensions, original bytes, result bytes, savings percentage, state, and remove action.
3. Inspector: zoomable before-and-after split view, format, quality, resize controls, metadata policy, and live recompression indicator.
4. Completion state: summary by success and failure, ZIP size, filenames, and a reminder that refreshing discards all local work.

CORE CAPABILITIES
1. drag-and-drop or file picker for multiple images
2. quality controls with sensible per-format defaults
3. before and after dimensions, bytes, and percentage saved
4. side-by-side preview for the selected image
5. download one file or all results as a ZIP

DETAILED BEHAVIOR AND BUSINESS RULES
Treat these as server-enforced product requirements, not interface suggestions:
1. Process files entirely in the browser, revoke object URLs after use, and never send image bytes to analytics or a server.
2. Preserve aspect ratio by default, prevent accidental upscaling, enforce pixel and memory limits, and explain unsupported browser capabilities.
3. Never replace the original file in place; produce a deterministic suffix and resolve duplicate output names inside ZIP downloads.
4. Run a bounded number of compression jobs concurrently so a large batch keeps the interface responsive and can be canceled.

DATA MODEL AND LIFECYCLE
Design a small relational schema centered on local ProcessingJob and ImageResult objects only. 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, Alpine, Browser API 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 browser Canvas and WebCodecs when supported. 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
Process images in the browser by default so originals never leave the device.
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. A valid JPEG batch finishes without network requests and download-all returns a ZIP containing one result for each successful source.
2. An oversized or unsupported image fails independently with a clear reason while the rest of the batch continues processing.
3. Changing quality updates the selected preview and byte estimate, but does not affect other files until apply-to-selected is confirmed.

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 add accounts, cloud storage, billing, or an image CDN.

You are building a production-ready software product named “Squooshbox”, a deliberately focused alternative to TinyPNG Pro. 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 designer compressing batches of web images.
Primary outcome: compress common image formats locally and make the savings obvious.
Product principle: optimize the exact workflow below instead of copying the full breadth of TinyPNG Pro. 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 user drops a mixed batch of images, watches each file validate and compress locally, then compares original and result sizes.
2. The user selects one image, adjusts output format and quality, examines a split preview, and applies those settings to selected files.
3. The user downloads one optimized image or a ZIP with predictable names, while unsupported and failed files remain clearly identified.

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. Workspace: prominent drop zone, file picker, privacy statement, batch list, overall bytes saved, clear-all, and download-all controls.
2. Image row: thumbnail, source and output format, dimensions, original bytes, result bytes, savings percentage, state, and remove action.
3. Inspector: zoomable before-and-after split view, format, quality, resize controls, metadata policy, and live recompression indicator.
4. Completion state: summary by success and failure, ZIP size, filenames, and a reminder that refreshing discards all local work.

CORE CAPABILITIES
1. drag-and-drop or file picker for multiple images
2. quality controls with sensible per-format defaults
3. before and after dimensions, bytes, and percentage saved
4. side-by-side preview for the selected image
5. download one file or all results as a ZIP

DETAILED BEHAVIOR AND BUSINESS RULES
Treat these as server-enforced product requirements, not interface suggestions:
1. Process files entirely in the browser, revoke object URLs after use, and never send image bytes to analytics or a server.
2. Preserve aspect ratio by default, prevent accidental upscaling, enforce pixel and memory limits, and explain unsupported browser capabilities.
3. Never replace the original file in place; produce a deterministic suffix and resolve duplicate output names inside ZIP downloads.
4. Run a bounded number of compression jobs concurrently so a large batch keeps the interface responsive and can be canceled.

DATA MODEL AND LIFECYCLE
Design a small relational schema centered on local ProcessingJob and ImageResult objects only. 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, Alpine, Browser API 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 browser Canvas and WebCodecs when supported. 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
Process images in the browser by default so originals never leave the device.
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. A valid JPEG batch finishes without network requests and download-all returns a ZIP containing one result for each successful source.
2. An oversized or unsupported image fails independently with a clear reason while the rest of the batch continues processing.
3. Changing quality updates the selected preview and byte estimate, but does not affect other files until apply-to-selected is confirmed.

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 add accounts, cloud storage, billing, or an image CDN.