Middleware API¶

Module: src/middleware.py

The middleware module patches DeepAgents' skill parser to add environment variable and bridge availability checks. It is imported as a side-effect in src/agent.py.

init_middleware_bridges¶

def init_middleware_bridges(gateway_config: GatewayConfig) -> None

Sets the available bridges for skill filtering. Called at startup in src/main.py when the gateway is enabled.

# src/main.py
if config.gateway.enabled:
    init_middleware_bridges(config.gateway)

After initialization, skills that declare requires_bridge in their YAML frontmatter will be skipped if the required bridge is not configured.

Skill Filtering¶

The module monkey-patches deepagents.middleware.skills._parse_skill_metadata with a custom implementation that adds two checks before delegating to the original parser.

requires_env¶

---
name: My Skill
requires_env: "MY_API_KEY"
---

The skill is skipped if any listed environment variables are not set. Supports both a single string and a list:

requires_env: ["API_KEY_1", "API_KEY_2"]

requires_bridge¶

---
name: Spotify Skill
requires_bridge: "spotify"
---

The skill is skipped if any listed bridges are not in gateway.bridges. Supports both a single string and a list:

requires_bridge: ["spotify", "sonos"]

YAML Auto-Fix¶

If the original DeepAgents parser fails on a skill's frontmatter (common with unquoted values containing colons), the middleware attempts an automatic fix:

Detects unquoted values with embedded : patterns
Wraps them in double quotes
Retries the original parser with the fixed content

Internal Functions¶

Function	Description
`_extract_frontmatter_field(content, field)`	Extracts a single field from YAML frontmatter
`_extract_requires_env(content)`	Extracts `requires_env` from frontmatter
`_check_env_requirements(requires, skill_name)`	Returns `False` if env vars are missing
`_extract_requires_bridge(content)`	Extracts `requires_bridge` from frontmatter
`_check_bridge_requirements(requires, skill_name)`	Returns `False` if bridges are unavailable
`_robust_parse_skill_metadata(content, skill_path, directory_name)`	Replacement parser with filtering + auto-fix

How It Works¶

flowchart TD A[Skill YAML loaded] --> B{requires_env set?} B -->|Yes| C{Env vars present?} B -->|No| D{requires_bridge set?} C -->|No| E[Skip skill] C -->|Yes| D D -->|Yes| F{Bridges available?} D -->|No| G[Original parser] F -->|No| E F -->|Yes| G G --> H{Parse OK?} H -->|Yes| I[Return metadata] H -->|No| J[Auto-fix YAML] J --> K{Retry OK?} K -->|Yes| I K -->|No| L[Return None]