Envision is a TUI framework that renders to terminal emulators. Its security boundaries are:

What envision manages:

• Rendering styled text and widgets to the terminal via ratatui
• Processing keyboard and mouse events from crossterm
• Managing component state through The Elm Architecture (TEA) pattern

What envision does NOT manage:

• Network I/O, file system access, or any external resource access
• Authentication, authorization, or session management
• Encryption or cryptographic operations

Side effects (network calls, file I/O, etc.) are the responsibility of application code within Command callbacks, not the framework itself.

Terminal applications face a unique attack surface: malicious content rendered to the terminal can include escape sequences that exploit vulnerabilities in terminal emulators.

• Ratatui handles rendering. All text output goes through ratatui's Buffer abstraction, which maps styled characters to cells rather than writing raw escape sequences. Ratatui and crossterm together handle the translation from logical cells to terminal output.
• No raw write! to stdout. Envision never writes raw bytes to the terminal directly. All rendering is mediated by ratatui's Backend trait.
• Component API is safe by default. Components such as ConversationView (renders via Paragraph) and TerminalOutput (parses ANSI codes into ratatui Style values via parse_ansi, then renders them as Span::styled) never forward raw escape bytes to the terminal. User-provided text passed through envision's component API is inherently safe against terminal escape injection.
• ANSI parser is hardened. The parse_ansi function (src/component/terminal_output/ansi.rs) only processes SGR codes (Select Graphic Rendition — text styling). It supports standard colors (16), 256-color indexed palette (38;5;n), 24-bit RGB (38;2;r;g;b), and text modifiers (bold, italic, underline). All non-SGR sequences (cursor movement, window manipulation, etc.) are silently dropped. The parser is fuzz-tested with proptest using arbitrary Unicode input to verify it never panics.
• CaptureBackend for testing. The headless CaptureBackend never interacts with a real terminal, eliminating escape sequence concerns in test environments entirely.

If application code constructs Span::raw() or Line values containing escape sequences and renders them directly through ratatui (bypassing envision's component API), those sequences will reach the terminal. This is a ratatui/crossterm concern rather than one specific to envision. Envision makes no guarantee about content rendered outside its component API.

If your application displays user-provided or external content (log files, chat messages, API responses, etc.):

1. Sanitize before storing. Strip or replace control characters (U+0000–U+001F, U+007F, U+0080–U+009F) from untrusted input before storing it in your application state. The TEA pattern makes this straightforward — validate in your update function.
2. Prefer envision components over raw ratatui primitives. Rendering user-provided strings through envision components (ConversationView, TerminalOutput, StyledText, etc.) is safer than constructing Span::raw() directly from unsanitized input.
3. Limit string lengths. Unbounded strings can cause excessive memory use or slow rendering. Truncate or paginate long content.
4. ANSI content is safe through TerminalOutput. The TerminalOutput component's parse_ansi function safely extracts styling from ANSI escape codes and discards everything else. It is safe to render log output, command output, and other ANSI-containing content through this component without stripping.

Envision components perform boundary validation internally:

• Index clamping. List, table, and tree components clamp selection indices to valid ranges. Out-of-bounds indices do not cause panics.
• Empty collection safety. All components handle empty data gracefully (empty lists, zero items, no tabs).
• Resize handling. Components adapt to terminal resize events without crashing.

For application-level input validation:

• Validate user input in your update function before modifying state
• Use the type system to enforce invariants (the TEA pattern's Message enum naturally restricts valid operations)
• The Command type's try_perform_async method routes errors to a dedicated error channel rather than panicking

Envision's runtime dependencies are:

All dependencies are well-maintained crates from the Rust ecosystem. Envision contains zero unsafe code.

Envision is designed to avoid panics on valid input:

• No unwrap() on user-provided data
• Index operations use bounds checking or clamping
• Pattern matches are exhaustive
• The Component trait's update function returns Option rather than panicking on unhandled messages

If you discover a case where envision panics on valid input, please report it as a bug.

If you discover a security vulnerability in envision, please report it responsibly:

1. Do not open a public issue. Security vulnerabilities should be reported privately.
2. Email the maintainer at the email address listed in the crates.io package metadata or use GitHub's private vulnerability reporting.
3. Include details: affected versions, reproduction steps, and potential impact.
4. Expected response time: We aim to acknowledge reports within 48 hours and provide a fix or mitigation plan within 7 days for confirmed vulnerabilities.

We will credit reporters in the advisory and CHANGELOG unless they prefer to remain anonymous.