Simple HTTP Auth designed

specs/005-simple-http-auth/spec.md

@@ -0,0 +1,87 @@
+# Feature Specification: Simple HTTP Auth
+
+**Feature Branch**: `005-simple-http-auth`  
+**Created**: October 13, 2025  
+**Status**: Draft  
+**Input**: User description: "Simple HTTP Auth. I create a passphrase in the .env file, and users must enter the passphrase (without username) to get access to the SPA. The access must be preserved during session."
+
+## User Scenarios & Testing *(mandatory)*
+
+### User Story 1 - Accessing the SPA (Priority: P1)
+
+A user attempts to access the Single Page Application (SPA). They are prompted to enter a passphrase. Upon entering the correct passphrase, they gain access to the SPA. This access is maintained throughout their session.
+
+**Why this priority**: This is the core functionality of the feature, enabling controlled access to the application.
+
+**Independent Test**: Can be fully tested by navigating to the SPA, entering a valid passphrase, and verifying access to content.
+
+**Acceptance Scenarios**:
+
+1. **Given** a user navigates to the SPA, **When** they are presented with a passphrase input, **Then** they can enter the correct passphrase.
+2. **Given** a user has entered the correct passphrase, **When** they are redirected to the SPA content, **Then** their access is preserved across page navigations within the SPA.
+3. **Given** a user has entered the correct passphrase, **When** they close and reopen the browser (within a reasonable session timeout), **Then** they are still granted access without re-entering the passphrase.
+
+---
+
+### User Story 2 - Invalid Passphrase (Priority: P2)
+
+A user attempts to access the SPA but enters an incorrect passphrase. They should be denied access and prompted to try again.
+
+**Why this priority**: Essential for security and user experience, preventing unauthorized access.
+
+**Independent Test**: Can be tested by entering an incorrect passphrase and verifying that access is denied.
+
+**Acceptance Scenarios**:
+
+1. **Given** a user navigates to the SPA, **When** they enter an incorrect passphrase, **Then** they are shown an error message and remain on the passphrase entry screen.
+
+---
+
+### Edge Cases
+
+- What happens when the passphrase in the `.env` file is missing or invalid? (Answer: Default to No Authentication - the application starts without requiring a passphrase.)
+- How does the system handle multiple failed passphrase attempts? (Answer: No Rate Limiting - unlimited attempts allowed.)
+What defines “session” for preserving access? (Answer: Browser Session - Access is preserved only as long as the browser tab/window remains open. Closing the browser or tab will require re-entry of the passphrase.)
+
+## Requirements *(mandatory)*
+
+### Functional Requirements
+
+- **FR-001**: The system MUST prompt users to enter a passphrase before granting access to the SPA.
+- **FR-002**: The system MUST validate the entered passphrase against a configured passphrase.
+- **FR-003**: The system MUST grant access to the SPA upon successful passphrase validation.
+- **FR-004**: The system MUST deny access and provide feedback upon unsuccessful passphrase validation.
+- **FR-005**: The system MUST preserve user access to the SPA for the duration of their session.
+- **FR-006**: The passphrase MUST be configurable via an environment variable (e.g., `.env` file).
+- **FR-007**: The authentication mechanism MUST NOT require a username.
+- **FR-008**: The system MUST log both successful and failed authentication attempts to a text file, without sensitive data.
+
+### Key Entities *(include if feature involves data)*
+
+- **Passphrase**: A secret string used for authentication.
+- **Session**: A period of continuous interaction between the user and the SPA, during which access is maintained.
+
+## Out of Scope
+
+- User management (creation, deletion, modification of users)
+- Password reset or recovery functionality
+- Multi-factor authentication (MFA)
+
+## Success Criteria *(mandatory)*
+
+### Measurable Outcomes
+
+- **SC-001**: 100% of users who enter the correct passphrase gain immediate access to the SPA.
+- **SC-002**: 0% of users who enter an incorrect passphrase gain access to the SPA.
+- **SC-003**: User access to the SPA is maintained for the entire browser session (or defined session duration) without re-authentication.
+- **SC-004**: The passphrase can be updated in the `.env` file and takes effect upon application restart.
+
+## Clarifications
+
+### Session 2025-10-13
+
+- Q: What is the desired rate limiting behavior for multiple failed passphrase attempts? → A: No Rate Limiting
+- Q: How should the system behave if the passphrase is missing or invalid in the `.env` file? → A: Default to No Authentication
+- Q: Are there any specific performance targets (e.g., latency) for the passphrase validation process? → A: No target
+- Q: What kind of logging or monitoring should be in place for authentication attempts (success/failure)? → A: Standard Logging (both successful and failed attempts, without sensitive data, to a text file)
+- Q: Are there any explicit functionalities that are out-of-scope for this simple HTTP authentication (e.g., user management, password reset, multi-factor authentication)? → A: All of the above (User management, password reset, and MFA are all out-of-scope).