A reset refused by a bounded execution answers 409, not a bare 422

[jhgaylor]

:execution_fenced reached API callers through the unmapped-atom safety net: a 422 with no body at all, plus a warning log on every refusal. It is the third reason reset_sandbox/2 refuses (ADR 0046), and it should read like the other two.

It now answers 409 execution_fenced with a message, beside sandbox_mid_turn and sandbox_reset_pending. The message carries what separates it from both: a running turn ends by itself and a pending reset wants an operator, but an unconfirmed remote stop clears on its own once the deadline coordinator ages the obligation out — so the caller waits rather than fetching anyone.

Both defects are live on main today, after #1744 and #1745 landed. This does not touch the held #1746–#1752.

The regression is the interesting part

It builds a journal that genuinely owes a stop: claim the spawn, bind an identity, then fail the turn, which lands the row on ready. Without those two steps complete/3 takes the "no spawn was ever submitted" path straight to stopped, nothing is owed, and the reset succeeds — my first draft passed against the unfixed code. Reverting the clause turns the 409 back into a 422, which is what the test exists to catch.

ADR 0046 corrections

• Sprites chore: clean up compile warnings #33 merged on 2026-09-08. It was still written as an outstanding external dependency for provider identity notifications.
• The activation blocker is now stated. FOUNTAIN_EXECUTION_LIMITS is a single host-wide ceiling with no per-provider scope, and _unsafe_register_bounded/3 rolls back :provider_not_supported inside the admission transaction. So setting it on a deployment that also runs E2B, Daytona or self-hosted runners stops those conversations opening a turn at all; runtime.exs validates only the JSON shape and nothing warns the operator. The per-account ceiling is usable only for an account that never touches another provider, unchecked. Per-provider granularity is follow-up under Track remaining lifecycle extractions from #1754 #1864 — until it lands, the host ceiling is unsettable in production and the per-account one is Sprites-only.

Validation

• sandbox_reset_controller_test: 7 tests, 0 failures; the new one fails (422) with the clause reverted.
• Controllers + sandbox reset suites: 1,178 tests, 0 failures.
• mix format --check-formatted and mix compile --warnings-as-errors clean; okf validate decisions reports valid: true; the index needs no refresh (frontmatter unchanged).

🤖 Generated with Claude Code

https://claude.ai/code/session_01R9reKpmXUUJf4eUMULogie