aos-mcp-broker: call install_aos before handling traffic

Error message

aos-mcp-broker: call install_aos before handling traffic

What it means

This is a panic from an internal OnceCell-style registry: `McpIdentity` was never installed, so `identity()` cannot return a value and the `.expect` aborts. The broker requires `install_aos` (which populates IDENTITY) to run before any MCP traffic handling. It is an initialization-ordering guard, not a data error.

Solutions

Call `install_aos(...)` with the proper McpIdentity at process startup, before any request handling or topic/tag lookup.
Check that the code path calling log_tag/mcp_tool_prefix/tools_list_topic/audit_topic is not executed before initialization (move it after init or defer it).
In tests, add a setup fixture that calls install_aos once before the helpers under test.

Example fix

// before
let tag = broker::log_tag();

// after
broker::install_aos(&identity_config);
let tag = broker::log_tag();

Defensive patterns

Strategy: try-catch

Validate before calling

// Rust: guard before calling helpers
assert!(broker::is_initialized(), "call install_aos before handling traffic");
let tag = broker::log_tag();

Type guard

fn identity_installed() -> bool { broker::is_initialized() }

Try / catch

// Use std::panic::catch_unwind only at the boundary; the real fix is init ordering
let tag = std::panic::catch_unwind(broker::log_tag)
    .unwrap_or_else(|_| "uninitialized");

Prevention

Call install_aos as the first statement in main before spawning any handlers.
Add an integration test that exercises every public broker helper in a fresh process.
Route helper access through a single init-checked entry point.

When it happens

Trigger: Calling `log_tag()`, `mcp_tool_prefix()`, `tools_list_topic()`, or `audit_topic()` before `install_aos(...)` has been invoked; also any request handler path that transitively calls `identity()` during early startup or in tests that skip setup.

Common situations: Forgetting broker initialization in a new binary entrypoint, constructing MCP tool names/audit topics in static or lazy contexts that run before install, or writing unit tests that call helper functions without a setup harness.

Related errors

AI-assisted analysis of unicity-aos/aos-ce@f6f22024fb (2026-09-13). Data as JSON: /api/errors/ae9acca14fcd0d34. Report an issue: GitHub.

Appendix: source

Thrown at crates/aos-mcp-broker/src/profile.rs:25

static IDENTITY: OnceLock<&'static McpIdentity> = OnceLock::new();

/// Install the singleton AOS identity if it is not already set.
pub fn install_aos() {
    match IDENTITY.set(&McpIdentity::AOS) {
        Ok(()) => {}
        Err(existing) => assert!(
            core::ptr::eq(existing, &McpIdentity::AOS),
            "aos-mcp-broker: identity already installed"
        ),
    }
}

#[inline]
fn identity() -> &'static McpIdentity {
    IDENTITY
        .get()
        .copied()
        .expect("aos-mcp-broker: call install_aos before handling traffic")
}

#[inline]
pub(crate) fn log_tag() -> &'static str {
    identity().log_tag
}

#[inline]
pub(crate) fn mcp_tool_prefix() -> &'static str {
    identity().mcp_tool_prefix
}

#[inline]
pub(crate) fn tools_list_topic() -> &'static str {
    identity().tools_list_topic
}

#[inline]

View on GitHub (pinned to f6f22024fb)