# AGENTS.md — Build guide for Hevy Pro ## Project scope Prepare reusable routines, log sets during a workout and review transparent load/repetition trends. Let the user correct a set and explain any estimated personal-record formula. Catalogue verdict: yes. The core loop is small enough for a capable coding agent to produce a useful local version in one sitting. For Hevy Pro, log workouts and routines locally with neutral progress charts. The hard boundary is mobile apps, social features, watch integration, sync, and polished tracking, plus hardware data, content, coaching, and trust. 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 - Do not publish, spend money, contact customers, delete source data or run irreversible migrations without the project owner's authorization.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 supported Node release, a writable local data directory and a separate backup location. Bind to localhost; remote use requires authentication and HTTPS first. - 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: Social networking, clinical advice and guaranteed training outcomes are outside scope. ## 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: exercise definitions, routine versions, sessions, ordered sets, rest timers and personal-record calculations ## Security and data integrity - Reject unexpected origins and unbounded request bodies even on localhost. Keep credentials outside the database export and redact sensitive text from logs. - Correctness boundary: Completed sessions preserve their routine snapshot; estimates are labeled and missing sets are not counted as zero-effort performance. - 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: exercise definitions, routine versions, sessions, ordered sets, rest timers and personal-record calculations - Project rule — preserve this invariant: Completed sessions preserve their routine snapshot; estimates are labeled and missing sets are not counted as zero-effort performance. - Project rule — acceptance evidence: Edit a routine after a completed workout and retain historical exercise order; cancelling a rest timer cannot erase a logged set. ## 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 Hevy Pro-inspired workflow with owned or clearly labeled sample data: Prepare reusable routines, log sets during a workout and review transparent load/repetition trends. Let the user correct a set and explain any estimated personal-record formula. - Publish a reproducible walkthrough with this observable result: Edit a routine after a completed workout and retain historical exercise order; cancelling a rest timer cannot erase a logged set. - Explain who can operate this scoped tool, its setup and ongoing costs, and these remaining product gaps: Social networking, clinical advice and guaranteed training outcomes are outside scope. Avoid guaranteed savings, performance scores or implied endorsement. ## Engineering roadmap 1. Phase 1 — Scope and fixtures. Implement this bounded workflow: Prepare reusable routines, log sets during a workout and review transparent load/repetition trends. Let the user correct a set and explain any estimated personal-record formula. Record prerequisites, select representative user-owned fixtures and document the unsupported features: Social networking, clinical advice and guaranteed training outcomes are outside scope. 2. Phase 2 — Durable model. Model exercise definitions, routine versions, sessions, ordered sets, rest timers and personal-record calculations Add migrations or a versioned document format, explicit validation, stable IDs and a visible import-error report. Preserve this rule: Completed sessions preserve their routine snapshot; estimates are labeled and missing sets are not counted as zero-effort performance. 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. Reject unexpected origins and unbounded request bodies even on localhost. Keep credentials outside the database export and redact sensitive text 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. Edit a routine after a completed workout and retain historical exercise order; cancelling a rest timer cannot erase a logged set. 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 - mobile apps, social features, watch integration, sync, and polished tracking - wearable hardware data - coach network - clinical validation - large content library and social network ## Implementation prompt WORKING SLICE Prepare reusable routines, log sets during a workout and review transparent load/repetition trends. Let the user correct a set and explain any estimated personal-record formula. Build this scoped Hevy Pro-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 A supported Node release, a writable local data directory and a separate backup location. Bind to localhost; remote use requires authentication and HTTPS first. Outside this release: Social networking, clinical advice and guaranteed training outcomes are outside scope. Data model and correctness exercise definitions, routine versions, sessions, ordered sets, rest timers and personal-record calculations Invariant: Completed sessions preserve their routine snapshot; estimates are labeled and missing sets are not counted as zero-effort performance. 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 Reject unexpected origins and unbounded request bodies even on localhost. Keep credentials outside the database export and redact sensitive text 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: Prepare reusable routines, log sets during a workout and review transparent load/repetition trends. Let the user correct a set and explain any estimated personal-record formula. Record prerequisites, select representative user-owned fixtures and document the unsupported features: Social networking, clinical advice and guaranteed training outcomes are outside scope. 2. Phase 2 — Durable model. Model exercise definitions, routine versions, sessions, ordered sets, rest timers and personal-record calculations Add migrations or a versioned document format, explicit validation, stable IDs and a visible import-error report. Preserve this rule: Completed sessions preserve their routine snapshot; estimates are labeled and missing sets are not counted as zero-effort performance. 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. Reject unexpected origins and unbounded request bodies even on localhost. Keep credentials outside the database export and redact sensitive text 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. Edit a routine after a completed workout and retain historical exercise order; cancelling a rest timer cannot erase a logged set. Repeat the workflow after restart and with a denied permission or unavailable dependency; show recoverable failure rather than a success placeholder. Acceptance Edit a routine after a completed workout and retain historical exercise order; cancelling a rest timer cannot erase a logged set. 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: exercise definitions, routine versions, sessions, ordered sets, rest timers and personal-record calculations Project rule — preserve this invariant: Completed sessions preserve their routine snapshot; estimates are labeled and missing sets are not counted as zero-effort performance. Project rule — acceptance evidence: Edit a routine after a completed workout and retain historical exercise order; cancelling a rest timer cannot erase a logged set. ## 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.