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The Skills and Plugin system provides the extensibility framework for Palyra. It allows the platform to safely execute third-party capabilities—ranging from simple data transformations to complex API integrations—within a strictly governed and sandboxed environment. Capabilities are packaged as Skills, which contain metadata, security manifests, and compiled Plugins (WebAssembly modules). The system ensures that every plugin execution is resource-constrained, audited, and bound by explicit capability grants.

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System Architecture

The following diagram illustrates the relationship between a Skill’s definition in the “Natural Language Space” (manifests and tool descriptions) and its execution in the “Code Entity Space” (WASM runtimes and host bindings).

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Skill Execution Flow

Sources: crates/palyra-daemon/src/wasm_plugin_runner.rs#96-126, crates/palyra-plugins/runtime/src/lib.rs#105-110, crates/palyra-skills/src/models.rs#1-50

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Skills: Packaging and Trust

A Skill is the unit of distribution in Palyra. It is a signed artifact (.palyra-skill) containing a skill.toml manifest and one or more WASM modules.

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The Skill Manifest

The skill.toml file defines the identity of the skill, the tools it exposes to the LLM, and the specific capabilities (like network access or secret retrieval) it requires.
ComponentDescriptionCode Reference
Identityskill_id, version, and publisher.crates/palyra-skills/examples/echo-http/skill.toml#2-5
ToolsJSON Schema definitions for tool inputs and outputs.crates/palyra-skills/examples/echo-http/skill.toml#8-22
CapabilitiesExplicit allowlists for HTTP hosts, secrets, and filesystem paths.crates/palyra-skills/examples/echo-http/skill.toml#24-36
QuotasResource limits like fuel_budget and max_memory_bytes.crates/palyra-skills/examples/echo-http/skill.toml#37-41

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Trust and Verification

Palyra uses a Trust-on-First-Use (TOFU) model combined with cryptographic signing. Artifacts are verified using Ed25519 signatures before installation. The SkillTrustStore manages known publishers and their public keys. For details on signing, verification, and the lifecycle states (e.g., Quarantine), see Skills Lifecycle and Trust. Sources: crates/palyra-skills/src/lib.rs#11-24, crates/palyra-skills/examples/echo-http/skill.toml#1-45

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Plugins: WASM Runtime

The execution of skill logic happens within the palyra-plugins-runtime. This crate utilizes wasmtime to provide a high-performance, memory-safe sandbox.

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Resource Constraints

To prevent “noisy neighbor” issues or malicious resource exhaustion, every plugin run is governed by RuntimeLimits:

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Host Capability Bindings

Plugins cannot access the host system directly. They must use the palyra-plugins-sdk to interact with the host via a handle-based system. The runtime injects CapabilityHandles which represent specific granted permissions (e.g., a handle for a specific allowlisted HTTP host). For details on the SDK and runtime internals, see WASM Plugin Runtime. Sources: crates/palyra-plugins/runtime/src/lib.rs#24-40, crates/palyra-plugins/runtime/src/lib.rs#160-186, crates/palyra-daemon/src/wasm_plugin_runner.rs#18-30

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Child Pages

  • Skills Lifecycle and Trust: Deep dive into palyra-skills, skill.toml schemas, artifact signing, the SkillTrustStore, and periodic re-auditing.
  • WASM Plugin Runtime: Technical details of palyra-plugins-runtime, wasmtime configuration, fuel instrumentation, and the guest-host communication protocol.

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Child Pages