# AGENTS.md — Build guide for LnkFlow

## Project scope
Resolve a short link, apply configured UTM parameters without overwriting existing ad click IDs and issue a redirect. Log a minimal event asynchronously and offer a QR image for the stable short URL.

Catalogue verdict: kinda. A short link that 302s, logs the click, and injects UTMs is genuinely one sitting on Cloudflare Workers and KV, and the prompt below builds exactly that. What is not one sitting is the loop back out to the ad platforms. Meta and Google bid against the conversion events you send them, and since ATT the browser pixel misses a large share of purchases, which is the entire reason the Conversions API and offline conversion import exist. Closing that loop means persisting fbclid and gclid at redirect time, carrying that identity to a sale that happens days later on another device, posting a Purchase with a stable event_id so it deduplicates against the pixel, rebuilding fbc in Meta's fb.1.{timestamp}.{fbclid} form, importing offline conversions to Google on gclid, gbraid, or wbraid, and reversing all of it on refund. Every one of those fails silently. That is the expensive part: the dashboard still shows clicks while the bidder optimizes against nothing.
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- Do not publish, spend money, contact customers, delete source data or run irreversible migrations without the project owner's authorization.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
- Node, SQLite on persistent disk, public HTTPS hosting and an authenticated owner interface. Redirects are public; link creation and reports require owner authorization.
- Implementation components: Node.js, TypeScript and Express with server-rendered HTML and small browser modules. SQLite through better-sqlite3 with migrations, prepared statements and a single background worker.
- Scope boundary: Purchase events delivered back to Meta CAPI with stable event_id deduplication against the browser pixel; Google offline conversion import keyed on gclid, gbraid, or wbraid

## Stack and architecture
- Node.js, TypeScript and Express with server-rendered HTML and small browser modules.
- SQLite through better-sqlite3 with migrations, prepared statements and a single background worker.
- Domain model: short slugs, approved destinations, campaign parameters, redirect revisions and bounded click observations

## Security and data integrity
- Public routes accept only their documented inputs with rate/size limits. Protect every owner/customer action with authenticated authorization and CSRF checks; keep secrets outside exports and redact personal data from logs.
- Correctness boundary: Only allowed HTTP/HTTPS destinations are saved; analytics failures must not block redirects and sensitive query values are not logged.
- Use short SQLite transactions and persist job state before starting work. Give retries stable operation IDs; report incomplete or unknown results instead of silently repeating them.
- Use a consistent SQLite backup and an attachment manifest. Export portable JSON/CSV, then restore to a new directory without overwriting the original data.

## Agent implementation rules
- Project rule — data model: short slugs, approved destinations, campaign parameters, redirect revisions and bounded click observations
- Project rule — preserve this invariant: Only allowed HTTP/HTTPS destinations are saved; analytics failures must not block redirects and sensitive query values are not logged.
- Project rule — acceptance evidence: Redirect a URL containing gclid and preserve it exactly; a failed analytics write still returns the configured redirect and an expired slug returns a clear missing state.

## Optional agent skills and references
- 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.
- 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.

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 LnkFlow-inspired workflow with owned or clearly labeled sample data: Resolve a short link, apply configured UTM parameters without overwriting existing ad click IDs and issue a redirect. Log a minimal event asynchronously and offer a QR image for the stable short URL.
- Publish a reproducible walkthrough with this observable result: Redirect a URL containing gclid and preserve it exactly; a failed analytics write still returns the configured redirect and an expired slug returns a clear missing state.
- Explain who can operate this scoped tool, its setup and ongoing costs, and these remaining product gaps: Purchase events delivered back to Meta CAPI with stable event_id deduplication against the browser pixel; Google offline conversion import keyed on gclid, gbraid, or wbraid Avoid guaranteed savings, performance scores or implied endorsement.

## Engineering roadmap
1. Phase 1 — Scope and fixtures. Implement this bounded workflow: Resolve a short link, apply configured UTM parameters without overwriting existing ad click IDs and issue a redirect. Log a minimal event asynchronously and offer a QR image for the stable short URL. Record prerequisites, select representative user-owned fixtures and document the unsupported features: Purchase events delivered back to Meta CAPI with stable event_id deduplication against the browser pixel; Google offline conversion import keyed on gclid, gbraid, or wbraid
2. Phase 2 — Durable model. Model short slugs, approved destinations, campaign parameters, redirect revisions and bounded click observations Add migrations or a versioned document format, explicit validation, stable IDs and a visible import-error report. Preserve this rule: Only allowed HTTP/HTTPS destinations are saved; analytics failures must not block redirects and sensitive query values are not logged.
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. Use short SQLite transactions and persist job state before starting work. Give retries stable operation IDs; report incomplete or unknown results instead of silently repeating them.
4. Phase 4 — Permissions and integration failure. Public routes accept only their documented inputs with rate/size limits. Protect every owner/customer action with authenticated authorization and CSRF checks; keep secrets outside exports and redact personal data from logs. Request integration credentials and permissions only for the enabled feature; show a disconnected state instead of mock results.
5. Phase 5 — Portable handoff. Use a consistent SQLite backup and an attachment manifest. Export portable JSON/CSV, then restore to a new directory without overwriting the original data. Include setup, operating limits, fixture walkthrough and shutdown/restart instructions in the README.
6. Phase 6 — Acceptance scenarios. Redirect a URL containing gclid and preserve it exactly; a failed analytics write still returns the configured redirect and an expired slug returns a clear missing state. 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
- Purchase events delivered back to Meta CAPI with stable event_id deduplication against the browser pixel
- Google offline conversion import keyed on gclid, gbraid, or wbraid
- click to lead to sale attribution that survives a multi-day gap, with refund reversal
- TLS on a customer's branded domain (Cloudflare for SaaS and 90-day DCV renewals, not one DNS record)
- per-creator performance and commission reporting

## Implementation prompt
WORKING SLICE
Resolve a short link, apply configured UTM parameters without overwriting existing ad click IDs and issue a redirect. Log a minimal event asynchronously and offer a QR image for the stable short URL.

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

Architecture
- Node.js, TypeScript and Express with server-rendered HTML and small browser modules.
- SQLite through better-sqlite3 with migrations, prepared statements and a single background worker.

Prerequisites and limits
Node, SQLite on persistent disk, public HTTPS hosting and an authenticated owner interface. Redirects are public; link creation and reports require owner authorization.
Outside this release: Purchase events delivered back to Meta CAPI with stable event_id deduplication against the browser pixel; Google offline conversion import keyed on gclid, gbraid, or wbraid

Data model and correctness
short slugs, approved destinations, campaign parameters, redirect revisions and bounded click observations
Invariant: Only allowed HTTP/HTTPS destinations are saved; analytics failures must not block redirects and sensitive query values are not logged.
Use short SQLite transactions and persist job state before starting work. Give retries stable operation IDs; report incomplete or unknown results instead of silently repeating them.

Security and privacy
Public routes accept only their documented inputs with rate/size limits. Protect every owner/customer action with authenticated authorization and CSRF checks; keep secrets outside exports and redact personal data from logs.

Recovery and export
Use a consistent SQLite backup and an attachment manifest. Export portable JSON/CSV, then restore to a new directory without overwriting the original data.

Implementation order
1. Phase 1 — Scope and fixtures. Implement this bounded workflow: Resolve a short link, apply configured UTM parameters without overwriting existing ad click IDs and issue a redirect. Log a minimal event asynchronously and offer a QR image for the stable short URL. Record prerequisites, select representative user-owned fixtures and document the unsupported features: Purchase events delivered back to Meta CAPI with stable event_id deduplication against the browser pixel; Google offline conversion import keyed on gclid, gbraid, or wbraid
2. Phase 2 — Durable model. Model short slugs, approved destinations, campaign parameters, redirect revisions and bounded click observations Add migrations or a versioned document format, explicit validation, stable IDs and a visible import-error report. Preserve this rule: Only allowed HTTP/HTTPS destinations are saved; analytics failures must not block redirects and sensitive query values are not logged.
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. Use short SQLite transactions and persist job state before starting work. Give retries stable operation IDs; report incomplete or unknown results instead of silently repeating them.
4. Phase 4 — Permissions and integration failure. Public routes accept only their documented inputs with rate/size limits. Protect every owner/customer action with authenticated authorization and CSRF checks; keep secrets outside exports and redact personal data from logs. Request integration credentials and permissions only for the enabled feature; show a disconnected state instead of mock results.
5. Phase 5 — Portable handoff. Use a consistent SQLite backup and an attachment manifest. Export portable JSON/CSV, then restore to a new directory without overwriting the original data. Include setup, operating limits, fixture walkthrough and shutdown/restart instructions in the README.
6. Phase 6 — Acceptance scenarios. Redirect a URL containing gclid and preserve it exactly; a failed analytics write still returns the configured redirect and an expired slug returns a clear missing state. Repeat the workflow after restart and with a denied permission or unavailable dependency; show recoverable failure rather than a success placeholder.

Acceptance
Redirect a URL containing gclid and preserve it exactly; a failed analytics write still returns the configured redirect and an expired slug returns a clear missing state.
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: [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.
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.
Project rule — data model: short slugs, approved destinations, campaign parameters, redirect revisions and bounded click observations
Project rule — preserve this invariant: Only allowed HTTP/HTTPS destinations are saved; analytics failures must not block redirects and sensitive query values are not logged.
Project rule — acceptance evidence: Redirect a URL containing gclid and preserve it exactly; a failed analytics write still returns the configured redirect and an expired slug returns a clear missing state.

## 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.