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v0.31.0 — Agent Safety & Discoverability

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@iemejia iemejia released this 28 Jun 15:22
· 3 commits to main since this release
v0.31.0
e18fca1

v0.31.0 — Agent Safety & Discoverability

This release transforms fabio into a fully safety-hardened, agent-native CLI with defense-in-depth controls and runtime discoverability that achieves 90% correctness with coding agents.

Agent Safety (New)

Three independent safety boundaries for agent deployments:

--readonly — Blocks all mutations (POST/PUT/PATCH/DELETE) at the HTTP transport layer before network dispatch. Read operations pass through normally.

FABIO_READONLY=1 fabio workspace list     # works
FABIO_READONLY=1 fabio workspace create   # BLOCKED (READONLY_MODE error)

--enable-commands / --disable-commands — Runtime command allowlists/denylists. Operators constrain which command groups an agent can access.

FABIO_ENABLE_COMMANDS=workspace,lakehouse fabio workspace list  # works
FABIO_ENABLE_COMMANDS=workspace,lakehouse fabio deploy plan     # BLOCKED (FORBIDDEN)

--wrap-untrusted — Wraps user-authored fields (displayName, description) with <<<UNTRUSTED>>>...<<<END_UNTRUSTED>>> markers to prevent prompt injection when agent processes fabio output.

All three support environment variables for operator-controlled enforcement.

MCP Server Safety (New)

The MCP server is now read-only by default:

fabio mcp serve                                    # 366 read-only tools
fabio mcp serve --allow-write                      # 810 tools (all)
fabio mcp serve --allow-write --allow-tool "workspace,lakehouse"  # scoped
fabio mcp serve --list-tools                       # inspect without starting

Stable Exit Codes (New)

Agents can branch on $? without JSON parsing:

Code Meaning
0 Success
1 Generic error
2 Usage error
3 AUTH_REQUIRED
4 FORBIDDEN / READONLY_MODE
5 NOT_FOUND
6 CONFLICT
7 RATE_LIMITED
8 TIMEOUT
9 NETWORK_ERROR

Runtime Discoverability (Enhanced)

--budget flag — Token-aware schema output that returns the richest subset within a token limit:

fabio context agent --budget 4000  # full detail for priority groups, compact for rest

222 inline examples — Every major command now has CLI usage examples accessible via fabio context describe <group> <cmd>.

56 output shape examples — Agents can see response shapes via fabio context examples <group> <cmd>.

Safety state introspection — fabio context agent now includes a safety field showing effective restrictions.

Agent Skill (Moved In-Repo)

The agent skill now ships at .agents/skills/fabio/ in the main repository. No more separate fabio-skills repo (archived). Install via:

npx skills add https://github.com/iemejia/fabio

Eval results: 90% pass rate (69/77 tests) with gpt-4o-mini in CI.

Documentation Simplified

  • Deleted COMMANDS.md and EXAMPLES.md — the binary is the documentation
  • All agent knowledge lives in commands.json (auto-generated + examples preserved)
  • fabio context agent/describe/find/workflow provides runtime discovery

Stats

  • 22 E2E safety tests covering all new features
  • 77-case promptfoo eval running in CI via Azure OpenAI
  • 749 unit tests passing
  • Binary size: 19 MB (656 KB embedded context data = 3.5%)

Full Changelog: v0.30.0...v0.31.0

Full Changelog: v0.30.0...v0.31.0

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