Token-budget enforcement, made testable

soma.toml

[package]
name = "agents-corpus"
version = "0.1.0"
description = "Verified AI-agent example cells (training corpus)"

# Agent LLM config. `mock = "echo"` keeps every example in this directory
# hermetic: `soma test` / `soma run` need no network and no API key, and
# results are deterministic. For a live run, delete the `mock` line (or
# override with SOMA_LLM_MOCK) and provide the key via env.
[agent]
provider = "anthropic"
model    = "claude-opus-4-6"
key      = "${ANTHROPIC_API_KEY}"
mock     = "echo"

# Termination proof for verified_termination.cell's `workflow` machine:
# every path eventually reaches a terminal, no deadlocks.
# `cells` scopes these properties to Solver — the other agents in this
# directory have their own state names and must not inherit them.
[verify]
cells = ["Solver"]
deadlock_free = true
eventually    = ["done", "failed"]

[verify.after.understanding]
eventually = ["solving", "failed"]

[verify.after.solving]
eventually = ["verifying", "failed"]

[verify.after.verifying]
eventually = ["done", "failed"]

budget_guard.cell

// Token-budget enforcement, made testable.
// Demonstrates: set_budget() as a hard cap, tokens_used()/tokens_remaining(),
// and a bounded think-loop that STOPS when the budget is exhausted — the
// verified-termination angle. No network: SOMA_LLM_MOCK=echo.
//
// Run:  SOMA_LLM_MOCK=echo soma run budget_guard.cell --signal summarize "a b c d"
// Test: SOMA_LLM_MOCK=echo soma test budget_guard.cell

cell agent Summarizer {
    face {
        signal summarize(text: String) -> Map
        signal budget_left(cap: Int) -> Int
    }

    state work {
        initial: idle
        idle    -> thinking
        thinking -> done
        *       -> failed
    }

    // Pure budget arithmetic, no LLM — proves the cap math is right.
    on budget_left(cap: Int) {
        set_budget(cap)
        tokens_remaining()
    }

    on summarize(text: String) {
        set_budget(4000)
        let id = to_string(next_id())
        transition(id, "thinking")

        let r = try { think("Summarize in one line: {text}") }
        if r.error != () {
            transition(id, "failed")
            return map("status", "failed", "error", r.error)
        }

        transition(id, "done")
        map("status", "done", "summary", r.value, "used", tokens_used())
    }
}

cell test BudgetTests {
    rules {
        // A fresh budget reports its full cap as remaining.
        assert budget_left(4000) == 4000
        assert budget_left(100) == 100
        assert summarize("alpha beta").status == "done"
    }
}