CoherynUI — Plugin Capabilities & Security Sandbox Architecture v1.0
Status: Approved Specification
Reference ADR: ADR-017: Public Plugin WIT ABI, Sandbox Capabilities, and Resource Budgets
1. Zero Ambient Authority Principle
All plugins executed by CoherynUI are treated as untrusted bytecode. They are executed within an isolated WebAssembly sandbox adhering to the Principle of Least Privilege:
- No Filesystem Access: Plugins cannot open, read, or write to arbitrary host disk paths.
- No Network Access: Outbound HTTP/TCP sockets are completely disabled.
- No Process Execution: Plugins cannot spawn child processes or execute shell commands.
- No Environment Access: Host environment variables and secrets are hidden from the guest.
2. Resource Metering & Isolation Boundaries
To prevent infinite loops, memory leaks, and Denial-of-Service attacks from untrusted third-party plugins:
| Resource Constraint | Default Limit | Enforcement Mechanism |
|---|---|---|
| Instruction Budget (Fuel) | 1,000,000 instructions | Wasmtime fuel consumption. Once exhausted, execution traps immediately (CY5001). |
| Linear Memory Heap | 32 MB | Enforced virtual memory page boundaries. |
| Execution Deadline | 1000 ms | Host watchdog timer terminates runaway guest threads. |
| Recursion Depth | Bounded stack depth | Protected against stack overflow attacks. |
3. CLI Management
# Add and verify plugin integrity
coherynui plugin add ./plugins/typography.wasm
# Inspect granted permissions
coherynui plugin permissions typography
# Verify byte integrity and magic header
coherynui plugin verify typography