diff --git a/CLAUDE.md b/CLAUDE.md
index 7d33d38..a0cc247 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -30,11 +30,14 @@ Compiler: Solidity 0.8.25, EVM target: cancun, optimizer enabled (1M runs). Fuzz
 
 ### Interfaces (`src/interface/`)
 
-- **IOrderBookV5** — Current stable interface. Vault-based order book with deposit/withdraw, add/remove orders, take orders (market buy), and clear (match two orders with bounty). IERC3156 flash loan compliant.
-- **IOrderBookV6** (`unstable/`) — Next version. Adds vaultless orders (vault ID `0` means tokens move directly from wallet) and output-based take order limits.
-- **IOrderBookV5OrderTaker / IOrderBookV5ArbOrderTaker** — Callback interfaces for takers receiving tokens during `takeOrders`.
+- **IOrderBookV6** — Current stable interface. Vault-based order book with deposit/withdraw, add/remove orders, take orders (market buy), and clear (match two orders with bounty). IERC3156 flash loan compliant. Supports vaultless orders (vault ID `0` means tokens move directly from wallet) and input/output-based take order limits via `IOIsInput` flag.
+- **IOrderBookV6OrderTaker / IOrderBookV6ArbOrderTaker** — Callback interfaces for takers receiving tokens during `takeOrders`.
 - **ierc3156/** — Flash loan interfaces (IERC3156FlashLender, IERC3156FlashBorrower).
-- **deprecated/** (v1-v4) — Old interface versions. Do not modify unless undeprecating.
+- **deprecated/** (v1-v5) — Old interface versions. Do not modify unless undeprecating.
+
+### Interface Lifecycle
+
+Stable interfaces live directly in `src/interface/`. New unstable interfaces go in `src/interface/unstable/` until stabilised. When stabilising, move from `unstable/` to `src/interface/` and move the previous stable version to `deprecated/v<N>/`.
 
 ### Key Types
 
@@ -58,7 +61,7 @@ rain.math.float/=lib/rain.interpreter.interface/lib/rain.math.float/src/
 
 - All reverts use custom errors — no `revert("string")` or `require()` with string messages.
 - Interfaces use `pragma solidity ^0.8.18` (note: differs from interpreter interface which uses `^0.8.25`).
-- Versioned naming: interfaces (`IOrderBookV5`), structs (`OrderV4`, `ClearConfigV2`), events (`AddOrderV3`), functions (`deposit3`, `withdraw3`).
+- Versioned naming: interfaces (`IOrderBookV6`), structs (`OrderV4`, `ClearConfigV2`), events (`AddOrderV3`), functions (`deposit4`, `withdraw4`).
 - Use `//forge-lint: disable-next-line(...)` comments for lint suppressions: `unused-import`, `mixed-case-variable`, `pascal-case-struct`.
 - Use `//forge-lint: disable-start(...)`/`disable-end(...)` for multi-line suppressions.
 - Branch naming: `YYYY-MM-DD-description`.
diff --git a/REUSE.toml b/REUSE.toml
index ed16e52..59cd08c 100644
--- a/REUSE.toml
+++ b/REUSE.toml
@@ -6,7 +6,9 @@ path = [
     ".github/workflows/**/",
     ".gitignore",
     ".gitmodules",
+    "CLAUDE.md",
     "README.md",
+    "audit/**/",
     "flake.lock",
     "flake.nix",
     "foundry.toml",
diff --git a/src/interface/unstable/IOrderBookV6.sol b/src/interface/IOrderBookV6.sol
similarity index 99%
rename from src/interface/unstable/IOrderBookV6.sol
rename to src/interface/IOrderBookV6.sol
index b2f8662..68bac8d 100644
--- a/src/interface/unstable/IOrderBookV6.sol
+++ b/src/interface/IOrderBookV6.sol
@@ -2,7 +2,7 @@
 // SPDX-FileCopyrightText: Copyright (c) 2020 thedavidmeister
 pragma solidity ^0.8.18;
 
-import {IERC3156FlashLender} from "../ierc3156/IERC3156FlashLender.sol";
+import {IERC3156FlashLender} from "./ierc3156/IERC3156FlashLender.sol";
 import {
     IInterpreterCallerV4,
     SignedContextV1,
@@ -12,7 +12,7 @@ import {
     IInterpreterV4,
     //forge-lint: disable-next-line(unused-import)
     IInterpreterStoreV3
-} from "../../../lib/rain.interpreter.interface/src/interface/unstable/IInterpreterCallerV4.sol";
+} from "../../lib/rain.interpreter.interface/src/interface/IInterpreterCallerV4.sol";
 
 /// Import unmodified structures from older versions of `IOrderBook`.
 import {
@@ -25,7 +25,7 @@ import {
     OrderV4,
     TakeOrderConfigV4,
     QuoteV2
-} from "../IOrderBookV5.sol";
+} from "./deprecated/v5/IOrderBookV5.sol";
 
 import {Float} from "rain.math.float/lib/LibDecimalFloat.sol";
 
diff --git a/src/interface/unstable/IOrderBookV6ArbOrderTaker.sol b/src/interface/IOrderBookV6ArbOrderTaker.sol
similarity index 100%
rename from src/interface/unstable/IOrderBookV6ArbOrderTaker.sol
rename to src/interface/IOrderBookV6ArbOrderTaker.sol
diff --git a/src/interface/unstable/IOrderBookV6OrderTaker.sol b/src/interface/IOrderBookV6OrderTaker.sol
similarity index 100%
rename from src/interface/unstable/IOrderBookV6OrderTaker.sol
rename to src/interface/IOrderBookV6OrderTaker.sol
diff --git a/src/interface/deprecated/v1/IOrderBookV1.sol b/src/interface/deprecated/v1/IOrderBookV1.sol
index cf88c22..d86efb1 100644
--- a/src/interface/deprecated/v1/IOrderBookV1.sol
+++ b/src/interface/deprecated/v1/IOrderBookV1.sol
@@ -10,8 +10,8 @@ import {
     Evaluable,
     SignedContext,
     IInterpreterCallerV1
-} from "rain.interpreter.interface/interface/deprecated/IInterpreterCallerV1.sol";
-import {IExpressionDeployerV3} from "rain.interpreter.interface/interface/deprecated/IExpressionDeployerV3.sol";
+} from "rain.interpreter.interface/interface/deprecated/v1/IInterpreterCallerV1.sol";
+import {IExpressionDeployerV3} from "rain.interpreter.interface/interface/deprecated/v1/IExpressionDeployerV3.sol";
 
 /// Configuration for a deposit. All deposits are processed by and for
 /// `msg.sender` so the vaults are unambiguous here.
diff --git a/src/interface/deprecated/v2/IOrderBookV2.sol b/src/interface/deprecated/v2/IOrderBookV2.sol
index 520e455..cdd246a 100644
--- a/src/interface/deprecated/v2/IOrderBookV2.sol
+++ b/src/interface/deprecated/v2/IOrderBookV2.sol
@@ -3,12 +3,12 @@
 pragma solidity ^0.8.18;
 
 import {IERC3156FlashLender} from "../../ierc3156/IERC3156FlashLender.sol";
-import {EvaluableConfig, Evaluable} from "rain.interpreter.interface/interface/deprecated/IInterpreterCallerV1.sol";
+import {EvaluableConfig, Evaluable} from "rain.interpreter.interface/interface/deprecated/v1/IInterpreterCallerV1.sol";
 import {
     SignedContextV1,
     IInterpreterCallerV2
-} from "rain.interpreter.interface/interface/deprecated/IInterpreterCallerV2.sol";
-import {IExpressionDeployerV2} from "rain.interpreter.interface/interface/deprecated/IExpressionDeployerV2.sol";
+} from "rain.interpreter.interface/interface/deprecated/v1/IInterpreterCallerV2.sol";
+import {IExpressionDeployerV2} from "rain.interpreter.interface/interface/deprecated/v1/IExpressionDeployerV2.sol";
 
 /// Configuration for a deposit. All deposits are processed by and for
 /// `msg.sender` so the vaults are unambiguous here.
diff --git a/src/interface/deprecated/v3/IOrderBookV3.sol b/src/interface/deprecated/v3/IOrderBookV3.sol
index 958e761..30c7ec1 100644
--- a/src/interface/deprecated/v3/IOrderBookV3.sol
+++ b/src/interface/deprecated/v3/IOrderBookV3.sol
@@ -3,13 +3,13 @@
 pragma solidity ^0.8.18;
 
 import {IERC3156FlashLender} from "../../ierc3156/IERC3156FlashLender.sol";
-import {EvaluableV2} from "rain.interpreter.interface/lib/caller/LibEvaluable.sol";
 import {
+    EvaluableV2,
     EvaluableConfigV3,
     IInterpreterCallerV2,
     SignedContextV1
-} from "rain.interpreter.interface/interface/deprecated/IInterpreterCallerV2.sol";
-import {IExpressionDeployerV3} from "rain.interpreter.interface/interface/deprecated/IExpressionDeployerV3.sol";
+} from "rain.interpreter.interface/interface/deprecated/v1/IInterpreterCallerV2.sol";
+import {IExpressionDeployerV3} from "rain.interpreter.interface/interface/deprecated/v1/IExpressionDeployerV3.sol";
 
 /// Import unmodified structures from older versions of `IOrderBook`.
 import {IO, ClearConfig, ClearStateChange} from "../v2/IOrderBookV2.sol";
diff --git a/src/interface/deprecated/v4/IOrderBookV4.sol b/src/interface/deprecated/v4/IOrderBookV4.sol
index 7cdcbf7..8d3b49d 100644
--- a/src/interface/deprecated/v4/IOrderBookV4.sol
+++ b/src/interface/deprecated/v4/IOrderBookV4.sol
@@ -11,7 +11,7 @@ import {
     IInterpreterV3,
     //forge-lint: disable-next-line(unused-import)
     IInterpreterStoreV2
-} from "../../../../lib/rain.interpreter.interface/src/interface/IInterpreterCallerV3.sol";
+} from "../../../../lib/rain.interpreter.interface/src/interface/deprecated/v2/IInterpreterCallerV3.sol";
 
 /// Import unmodified structures from older versions of `IOrderBook`.
 import {ClearStateChange, ClearConfig, IO} from "../v3/IOrderBookV3.sol";
diff --git a/src/interface/IOrderBookV5.sol b/src/interface/deprecated/v5/IOrderBookV5.sol
similarity index 99%
rename from src/interface/IOrderBookV5.sol
rename to src/interface/deprecated/v5/IOrderBookV5.sol
index 9fa6d60..8689efc 100644
--- a/src/interface/IOrderBookV5.sol
+++ b/src/interface/deprecated/v5/IOrderBookV5.sol
@@ -2,7 +2,7 @@
 // SPDX-FileCopyrightText: Copyright (c) 2020 thedavidmeister
 pragma solidity ^0.8.18;
 
-import {IERC3156FlashLender} from "./ierc3156/IERC3156FlashLender.sol";
+import {IERC3156FlashLender} from "../../ierc3156/IERC3156FlashLender.sol";
 import {
     EvaluableV4,
     IInterpreterCallerV4,
@@ -11,11 +11,11 @@ import {
     IInterpreterV4,
     //forge-lint: disable-next-line(unused-import)
     IInterpreterStoreV3
-} from "../../lib/rain.interpreter.interface/src/interface/unstable/IInterpreterCallerV4.sol";
+} from "../../../../lib/rain.interpreter.interface/src/interface/IInterpreterCallerV4.sol";
 
 /// Import unmodified structures from older versions of `IOrderBook`.
 //forge-lint: disable-start(unused-import)
-import {NoOrders, ZeroMaximumInput} from "./deprecated/v4/IOrderBookV4.sol";
+import {NoOrders, ZeroMaximumInput} from "../v4/IOrderBookV4.sol";
 //forge-lint: disable-end(unused-import)
 
 import {Float} from "rain.math.float/lib/LibDecimalFloat.sol";
diff --git a/src/interface/IOrderBookV5ArbOrderTaker.sol b/src/interface/deprecated/v5/IOrderBookV5ArbOrderTaker.sol
similarity index 100%
rename from src/interface/IOrderBookV5ArbOrderTaker.sol
rename to src/interface/deprecated/v5/IOrderBookV5ArbOrderTaker.sol
diff --git a/src/interface/IOrderBookV5OrderTaker.sol b/src/interface/deprecated/v5/IOrderBookV5OrderTaker.sol
similarity index 100%
rename from src/interface/IOrderBookV5OrderTaker.sol
rename to src/interface/deprecated/v5/IOrderBookV5OrderTaker.sol