# AGENTS.md — Build guide for ReSlug

## Project scope
Build a Workers redirect service with KV lookups and bounded D1 analytics. Support explicit country/device routing with a default URL, a stable QR endpoint and owner-only link management.

Catalogue verdict: yes. The redirect is a slug, a lookup, a 302, and a row in a table · Cloudflare Workers with KV and D1 does the whole job on the free tier, and the QR code is one library call. Routing rules, expiry, and password links are an afternoon more. What you cannot build in a sitting is permanence: your links only outlive the project if you keep renewing the domain and the account. The wrinkle with ReSlug specifically is that its free plan already includes a custom domain and real analytics at personal scale, so the DIY build is competing with 0 USD rather than 9 · build it for the ownership, not the savings.
Use the implementation prompt below to define the deliverable. Complete each phase's acceptance checks before extending the scope.

## Working agreement
- Inspect the repository and its existing instructions before choosing paths, dependencies or commands. Keep one coherent stack and explain changes to the proposed architecture.
- Plan a vertical slice that accepts a real input and produces the useful output described below. Persist only the state the prompt calls for; respect memory-only and upstream-managed workflows. Use fixtures only when they are clearly labelled.
- After scaffolding, document the actual install, development, check and build commands in README and keep them synchronized with the package or project manifest. Do not report commands as successful unless they ran.
- Work in small steps. At handoff, list implemented flows, checks actually performed, remaining blockers, and any credentials or provider setup the owner must supply.
- Do not publish, spend money, contact customers, delete source data or run irreversible migrations without the project owner's authorization.

## Prerequisites
- A Cloudflare account, Workers/KV/D1 access, Wrangler and a domain the owner controls. Verify current service quotas and configure secrets outside wrangler.toml.
- Implementation components: Cloudflare Workers and TypeScript with D1 as the authoritative link-definition/revision store, including a unique slug constraint; bounded clicks also live in D1. KV is an eventually consistent redirect cache derived from committed D1 definitions, with publication/reconciliation status for each revision. Wrangler-managed bindings/secrets, owner-authenticated administration and generated QR assets.
- Scope boundary: Domain renewal and Cloudflare account limits remain operational responsibilities.

## Stack and architecture
- Cloudflare Workers and TypeScript with D1 as the authoritative link-definition/revision store, including a unique slug constraint; bounded clicks also live in D1.
- KV is an eventually consistent redirect cache derived from committed D1 definitions, with publication/reconciliation status for each revision.
- Wrangler-managed bindings/secrets, owner-authenticated administration and generated QR assets.
- Domain model: authoritative D1 link definitions with unique slugs, revisions and publication state, derived KV redirect cache records, D1 click observations, routing rules and QR exports

## Security and data integrity
- Protect management with authenticated sessions and CSRF checks; validate redirect destinations and store no raw IPs or sensitive query strings. Bound public write/analytics payloads.
- Correctness boundary: KV propagation is eventually consistent and must be disclosed; a logging failure cannot prevent a redirect and sensitive query strings are not stored.
- Create a unique slug and revision in authoritative D1 first; a conflicting insert fails rather than replacing the link. Publish that revision to KV with an observable pending/published status and reconcile failed publications. Disclose cache propagation delay. Redirects do not wait for analytics; failed click logging does not break the destination.
- Export canonical D1 link definitions, revision/publication status and click records; back up configuration separately from secrets. Rebuild KV only from committed D1 definitions and reconcile the cache revision before declaring restoration complete.

## Agent implementation rules
- Project rule — data model: authoritative D1 link definitions with unique slugs, revisions and publication state, derived KV redirect cache records, D1 click observations, routing rules and QR exports
- Project rule — preserve this invariant: KV propagation is eventually consistent and must be disclosed; a logging failure cannot prevent a redirect and sensitive query strings are not stored.
- Project rule — acceptance evidence: A missing country falls back to the default destination; a duplicate custom slug is rejected and a D1 outage leaves redirects working.

## Optional agent skills and references
- Optional external skill: [sharp-edges](https://github.com/trailofbits/skills/blob/main/plugins/sharp-edges/skills/sharp-edges/SKILL.md) — Review security-sensitive APIs and configuration for dangerous defaults and easy-to-misuse interfaces. Review its instructions and compatibility before use; it does not grant deployment, data-access or publication permission.
- Optional external skill: [web-design-guidelines](https://github.com/vercel-labs/agent-skills/blob/main/skills/web-design-guidelines/SKILL.md) — Review web interfaces for accessibility, keyboard focus, forms, navigation and interaction quality. Review its instructions and compatibility before use; it does not grant deployment, data-access or publication permission.

Read the linked SKILL.md and its dependencies before adding a skill. Select only the skills matching this project's runtime and task; their documentation does not supply API access, credentials or approval to perform external actions. Pin the reviewed revision where the tool supports it. Follow the chosen agent's documented project-level installation mechanism.

## Distribution ideas
These are optional planning notes. Obtain the owner's approval before publishing or contacting anyone.
- Demonstrate the actual ReSlug-inspired workflow with owned or clearly labeled sample data: Build a Workers redirect service with KV lookups and bounded D1 analytics. Support explicit country/device routing with a default URL, a stable QR endpoint and owner-only link management.
- Publish a reproducible walkthrough with this observable result: A missing country falls back to the default destination; a duplicate custom slug is rejected and a D1 outage leaves redirects working.
- Explain who can operate this scoped tool, its setup and ongoing costs, and these remaining product gaps: Domain renewal and Cloudflare account limits remain operational responsibilities. Avoid guaranteed savings, performance scores or implied endorsement.

## Engineering roadmap
1. Phase 1 — Scope and fixtures. Implement this bounded workflow: Build a Workers redirect service with KV lookups and bounded D1 analytics. Support explicit country/device routing with a default URL, a stable QR endpoint and owner-only link management. Record prerequisites, select representative user-owned fixtures and document the unsupported features: Domain renewal and Cloudflare account limits remain operational responsibilities.
2. Phase 2 — Durable model. Model authoritative D1 link definitions with unique slugs, revisions and publication state, derived KV redirect cache records, D1 click observations, routing rules and QR exports Add migrations or a versioned document format, explicit validation, stable IDs and a visible import-error report. Preserve this rule: KV propagation is eventually consistent and must be disclosed; a logging failure cannot prevent a redirect and sensitive query strings are not stored.
3. Phase 3 — Complete the first useful path. Implement the workflow's input, review and output interface, with clear controls and explicit empty/error states. Create a unique slug and revision in authoritative D1 first; a conflicting insert fails rather than replacing the link. Publish that revision to KV with an observable pending/published status and reconcile failed publications. Disclose cache propagation delay. Redirects do not wait for analytics; failed click logging does not break the destination.
4. Phase 4 — Permissions and integration failure. Protect management with authenticated sessions and CSRF checks; validate redirect destinations and store no raw IPs or sensitive query strings. Bound public write/analytics payloads. Request integration credentials and permissions only for the enabled feature; show a disconnected state instead of mock results.
5. Phase 5 — Portable handoff. Export canonical D1 link definitions, revision/publication status and click records; back up configuration separately from secrets. Rebuild KV only from committed D1 definitions and reconcile the cache revision before declaring restoration complete. Include setup, operating limits, fixture walkthrough and shutdown/restart instructions in the README.
6. Phase 6 — Acceptance scenarios. A missing country falls back to the default destination; a duplicate custom slug is rejected and a D1 outage leaves redirects working. Repeat the workflow after restart and with a denied permission or unavailable dependency; show recoverable failure rather than a success placeholder.

## Paid-product capabilities outside this build
- links that outlive your own infrastructure · a domain you stop renewing takes every link with it
- bot filtering that actually works · the heuristics take iteration you will not do for one project
- geo and device routing rules, scheduled links, and click caps behind a dashboard instead of a config file
- bio pages and branded QR codes
- a REST API and webhooks other tools can call

## Implementation prompt
WORKING SLICE
Build a Workers redirect service with KV lookups and bounded D1 analytics. Support explicit country/device routing with a default URL, a stable QR endpoint and owner-only link management.

Build this scoped ReSlug-inspired workflow with a documented data model and visible failure states.

Architecture
- Cloudflare Workers and TypeScript with D1 as the authoritative link-definition/revision store, including a unique slug constraint; bounded clicks also live in D1.
- KV is an eventually consistent redirect cache derived from committed D1 definitions, with publication/reconciliation status for each revision.
- Wrangler-managed bindings/secrets, owner-authenticated administration and generated QR assets.

Prerequisites and limits
A Cloudflare account, Workers/KV/D1 access, Wrangler and a domain the owner controls. Verify current service quotas and configure secrets outside wrangler.toml.
Outside this release: Domain renewal and Cloudflare account limits remain operational responsibilities.

Data model and correctness
authoritative D1 link definitions with unique slugs, revisions and publication state, derived KV redirect cache records, D1 click observations, routing rules and QR exports
Invariant: KV propagation is eventually consistent and must be disclosed; a logging failure cannot prevent a redirect and sensitive query strings are not stored.
Create a unique slug and revision in authoritative D1 first; a conflicting insert fails rather than replacing the link. Publish that revision to KV with an observable pending/published status and reconcile failed publications. Disclose cache propagation delay. Redirects do not wait for analytics; failed click logging does not break the destination.

Security and privacy
Protect management with authenticated sessions and CSRF checks; validate redirect destinations and store no raw IPs or sensitive query strings. Bound public write/analytics payloads.

Recovery and export
Export canonical D1 link definitions, revision/publication status and click records; back up configuration separately from secrets. Rebuild KV only from committed D1 definitions and reconcile the cache revision before declaring restoration complete.

Implementation order
1. Phase 1 — Scope and fixtures. Implement this bounded workflow: Build a Workers redirect service with KV lookups and bounded D1 analytics. Support explicit country/device routing with a default URL, a stable QR endpoint and owner-only link management. Record prerequisites, select representative user-owned fixtures and document the unsupported features: Domain renewal and Cloudflare account limits remain operational responsibilities.
2. Phase 2 — Durable model. Model authoritative D1 link definitions with unique slugs, revisions and publication state, derived KV redirect cache records, D1 click observations, routing rules and QR exports Add migrations or a versioned document format, explicit validation, stable IDs and a visible import-error report. Preserve this rule: KV propagation is eventually consistent and must be disclosed; a logging failure cannot prevent a redirect and sensitive query strings are not stored.
3. Phase 3 — Complete the first useful path. Implement the workflow's input, review and output interface, with clear controls and explicit empty/error states. Create a unique slug and revision in authoritative D1 first; a conflicting insert fails rather than replacing the link. Publish that revision to KV with an observable pending/published status and reconcile failed publications. Disclose cache propagation delay. Redirects do not wait for analytics; failed click logging does not break the destination.
4. Phase 4 — Permissions and integration failure. Protect management with authenticated sessions and CSRF checks; validate redirect destinations and store no raw IPs or sensitive query strings. Bound public write/analytics payloads. Request integration credentials and permissions only for the enabled feature; show a disconnected state instead of mock results.
5. Phase 5 — Portable handoff. Export canonical D1 link definitions, revision/publication status and click records; back up configuration separately from secrets. Rebuild KV only from committed D1 definitions and reconcile the cache revision before declaring restoration complete. Include setup, operating limits, fixture walkthrough and shutdown/restart instructions in the README.
6. Phase 6 — Acceptance scenarios. A missing country falls back to the default destination; a duplicate custom slug is rejected and a D1 outage leaves redirects working. Repeat the workflow after restart and with a denied permission or unavailable dependency; show recoverable failure rather than a success placeholder.

Acceptance
A missing country falls back to the default destination; a duplicate custom slug is rejected and a D1 outage leaves redirects working.
Use real source data or clearly labeled fixtures. Explain unsupported input and provider failures; do not fabricate analytics, delivery receipts, accuracy claims or security guarantees.

Optional agent guidance
Optional external skill: [sharp-edges](https://github.com/trailofbits/skills/blob/main/plugins/sharp-edges/skills/sharp-edges/SKILL.md) — Review security-sensitive APIs and configuration for dangerous defaults and easy-to-misuse interfaces. Review its instructions and compatibility before use; it does not grant deployment, data-access or publication permission.
Optional external skill: [web-design-guidelines](https://github.com/vercel-labs/agent-skills/blob/main/skills/web-design-guidelines/SKILL.md) — Review web interfaces for accessibility, keyboard focus, forms, navigation and interaction quality. Review its instructions and compatibility before use; it does not grant deployment, data-access or publication permission.
Project rule — data model: authoritative D1 link definitions with unique slugs, revisions and publication state, derived KV redirect cache records, D1 click observations, routing rules and QR exports
Project rule — preserve this invariant: KV propagation is eventually consistent and must be disclosed; a logging failure cannot prevent a redirect and sensitive query strings are not stored.
Project rule — acceptance evidence: A missing country falls back to the default destination; a duplicate custom slug is rejected and a D1 outage leaves redirects working.

## Completion evidence
Demonstrate the prompt's acceptance scenarios against the scoped workflow. Include setup from a clean checkout and failure recovery. Check persistence across restart and export/restore only for the state the prompt says to store; for memory-only tools, confirm that temporary content is discarded as specified. Record actual results and remaining limitations. A detailed plan alone does not establish a working replacement.