# AGENTS.md — Build guide for Nitro PDF Pro ## Project scope Build a local PDF workspace for combine, reorder, annotate and controlled Office-to-PDF conversion. Preview outputs and preserve a manifest of fonts/forms/signatures that may change during conversion. Catalogue verdict: kinda. The core loop is buildable, but a dependable replacement becomes a real weekend or multi-day project. For Nitro PDF Pro, edit, convert, combine, and sign ordinary business PDFs locally. The hard boundary is format fidelity, office integration, ocr, support, and enterprise deployment, plus document fidelity, identity, and compliance. 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 - Do not publish, spend money, contact customers, delete source data or run irreversible migrations without the project owner's authorization.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 Python virtual environment, writable input/output directories and sufficient disk for both originals and outputs. Bind the service to localhost. - Implementation components: Python, FastAPI and server-rendered HTML with HTMX for a local interface. SQLite for manifests and job state, with an explicit worker process and immutable source files. - Scope boundary: Certified signing and perfect Office fidelity are outside scope. ## Stack and architecture - Python, FastAPI and server-rendered HTML with HTMX for a local interface. - SQLite for manifests and job state, with an explicit worker process and immutable source files. - Domain model: PDF source hashes, page operations, annotations, Office-conversion jobs and output warnings ## Security and data integrity - Bound file sizes and processing time, reject path traversal, and use argument arrays for subprocesses. Treat imported text as data and redact confidential source content from logs. - Correctness boundary: A drawn signature is not a cryptographic signature; redaction requires removing content rather than covering it with a rectangle. - Save a job manifest with input hash, parameters and state. Write to temporary outputs, then atomically finalize only successful results; resume unfinished jobs without replacing originals. - Export sources, manifests and outputs with checksums. Keep failed-job diagnostics and allow retry into a new output path; restore the database and file directory together. ## Agent implementation rules - Project rule — data model: PDF source hashes, page operations, annotations, Office-conversion jobs and output warnings - Project rule — preserve this invariant: A drawn signature is not a cryptographic signature; redaction requires removing content rather than covering it with a rectangle. - Project rule — acceptance evidence: Reopen a converted document and inspect page count and extracted text; a digitally signed input warns before a transformation that would invalidate its signature. ## Optional agent skills and references - Optional external skill: [modern-python](https://github.com/trailofbits/skills/blob/main/plugins/modern-python/skills/modern-python/SKILL.md) — Set up Python projects with pyproject.toml, dependency management, linting, typing and automated checks. 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. - 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: [pdf](https://github.com/anthropics/skills/blob/main/skills/pdf/SKILL.md) — Process PDFs through extraction, generation, page operations, form filling and OCR workflows. 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 Nitro PDF Pro-inspired workflow with owned or clearly labeled sample data: Build a local PDF workspace for combine, reorder, annotate and controlled Office-to-PDF conversion. Preview outputs and preserve a manifest of fonts/forms/signatures that may change during conversion. - Publish a reproducible walkthrough with this observable result: Reopen a converted document and inspect page count and extracted text; a digitally signed input warns before a transformation that would invalidate its signature. - Explain who can operate this scoped tool, its setup and ongoing costs, and these remaining product gaps: Certified signing and perfect Office fidelity are outside scope. Avoid guaranteed savings, performance scores or implied endorsement. ## Engineering roadmap 1. Phase 1 — Scope and fixtures. Implement this bounded workflow: Build a local PDF workspace for combine, reorder, annotate and controlled Office-to-PDF conversion. Preview outputs and preserve a manifest of fonts/forms/signatures that may change during conversion. Record prerequisites, select representative user-owned fixtures and document the unsupported features: Certified signing and perfect Office fidelity are outside scope. 2. Phase 2 — Durable model. Model PDF source hashes, page operations, annotations, Office-conversion jobs and output warnings Add migrations or a versioned document format, explicit validation, stable IDs and a visible import-error report. Preserve this rule: A drawn signature is not a cryptographic signature; redaction requires removing content rather than covering it with a rectangle. 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. Save a job manifest with input hash, parameters and state. Write to temporary outputs, then atomically finalize only successful results; resume unfinished jobs without replacing originals. 4. Phase 4 — Permissions and integration failure. Bound file sizes and processing time, reject path traversal, and use argument arrays for subprocesses. Treat imported text as data and redact confidential source content 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. Export sources, manifests and outputs with checksums. Keep failed-job diagnostics and allow retry into a new output path; restore the database and file directory together. Include setup, operating limits, fixture walkthrough and shutdown/restart instructions in the README. 6. Phase 6 — Acceptance scenarios. Reopen a converted document and inspect page count and extracted text; a digitally signed input warns before a transformation that would invalidate its signature. 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 - format fidelity, Office integration, OCR, support, and enterprise deployment - pixel-perfect proprietary PDF engine - identity verification - qualified trust services - large template and integration ecosystem ## Implementation prompt WORKING SLICE Build a local PDF workspace for combine, reorder, annotate and controlled Office-to-PDF conversion. Preview outputs and preserve a manifest of fonts/forms/signatures that may change during conversion. Build this scoped Nitro PDF Pro-inspired workflow with a documented data model and visible failure states. Architecture - Python, FastAPI and server-rendered HTML with HTMX for a local interface. - SQLite for manifests and job state, with an explicit worker process and immutable source files. Prerequisites and limits A Python virtual environment, writable input/output directories and sufficient disk for both originals and outputs. Bind the service to localhost. Outside this release: Certified signing and perfect Office fidelity are outside scope. Data model and correctness PDF source hashes, page operations, annotations, Office-conversion jobs and output warnings Invariant: A drawn signature is not a cryptographic signature; redaction requires removing content rather than covering it with a rectangle. Save a job manifest with input hash, parameters and state. Write to temporary outputs, then atomically finalize only successful results; resume unfinished jobs without replacing originals. Security and privacy Bound file sizes and processing time, reject path traversal, and use argument arrays for subprocesses. Treat imported text as data and redact confidential source content from logs. Recovery and export Export sources, manifests and outputs with checksums. Keep failed-job diagnostics and allow retry into a new output path; restore the database and file directory together. Implementation order 1. Phase 1 — Scope and fixtures. Implement this bounded workflow: Build a local PDF workspace for combine, reorder, annotate and controlled Office-to-PDF conversion. Preview outputs and preserve a manifest of fonts/forms/signatures that may change during conversion. Record prerequisites, select representative user-owned fixtures and document the unsupported features: Certified signing and perfect Office fidelity are outside scope. 2. Phase 2 — Durable model. Model PDF source hashes, page operations, annotations, Office-conversion jobs and output warnings Add migrations or a versioned document format, explicit validation, stable IDs and a visible import-error report. Preserve this rule: A drawn signature is not a cryptographic signature; redaction requires removing content rather than covering it with a rectangle. 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. Save a job manifest with input hash, parameters and state. Write to temporary outputs, then atomically finalize only successful results; resume unfinished jobs without replacing originals. 4. Phase 4 — Permissions and integration failure. Bound file sizes and processing time, reject path traversal, and use argument arrays for subprocesses. Treat imported text as data and redact confidential source content 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. Export sources, manifests and outputs with checksums. Keep failed-job diagnostics and allow retry into a new output path; restore the database and file directory together. Include setup, operating limits, fixture walkthrough and shutdown/restart instructions in the README. 6. Phase 6 — Acceptance scenarios. Reopen a converted document and inspect page count and extracted text; a digitally signed input warns before a transformation that would invalidate its signature. Repeat the workflow after restart and with a denied permission or unavailable dependency; show recoverable failure rather than a success placeholder. Acceptance Reopen a converted document and inspect page count and extracted text; a digitally signed input warns before a transformation that would invalidate its signature. 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: [modern-python](https://github.com/trailofbits/skills/blob/main/plugins/modern-python/skills/modern-python/SKILL.md) — Set up Python projects with pyproject.toml, dependency management, linting, typing and automated checks. 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. 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: [pdf](https://github.com/anthropics/skills/blob/main/skills/pdf/SKILL.md) — Process PDFs through extraction, generation, page operations, form filling and OCR workflows. Review its instructions and compatibility before use; it does not grant deployment, data-access or publication permission. Project rule — data model: PDF source hashes, page operations, annotations, Office-conversion jobs and output warnings Project rule — preserve this invariant: A drawn signature is not a cryptographic signature; redaction requires removing content rather than covering it with a rectangle. Project rule — acceptance evidence: Reopen a converted document and inspect page count and extracted text; a digitally signed input warns before a transformation that would invalidate its signature. ## 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.