diff --git a/.prettierignore b/.prettierignore
index d1b5d1a..f17f6ac 100644
--- a/.prettierignore
+++ b/.prettierignore
@@ -37,3 +37,6 @@ tmp/
 __pycache__/
 *.pyc
 *.egg-info/
+
+# Spec artifacts (quire-managed, not prettier-formatted)
+spec/
diff --git a/spec/functional/FR-024-plugin-catalog-library-api.md b/spec/functional/FR-024-plugin-catalog-library-api.md
new file mode 100644
index 0000000..025f291
--- /dev/null
+++ b/spec/functional/FR-024-plugin-catalog-library-api.md
@@ -0,0 +1,63 @@
+---
+id: FR-024
+title: "Expose plugin and catalog operations as a stable library API"
+relationships:
+  - target: "ix://agent-ix/quoin/StR-003"
+    type: "traces_to"
+  - target: "ix://agent-ix/quoin/US-003"
+    type: "implements"
+type: FR
+---
+
+# FR-024: Expose plugin and catalog operations as a stable library API
+
+## Description
+
+The package SHALL export its plugin install/list/remove and catalog-loading
+operations — `installPlugin`, `listPlugins`, `removePlugin`, `parseSourceArg`,
+`loadCatalog`, and `filamentModulesDir` — as a stable, semver-governed library API
+from `@agent-ix/quoin`, so that other Node tools can manage and read the same
+shared plugin store (`~/.ix/filament/registry.json` and `~/.ix/filament/modules/`)
+identically to the `quoin` CLI, in service of
+[StR-003](../stakeholder/StR-003-shared-catalog.md).
+
+The durable cross-tool contract is the **shared store layout** plus the
+`@agent-ix/ts-plugin-kit` source/registry model: a consumer may either import this
+library (Node tools) or interoperate at the store level over the same registry and
+module directories (as filament-ide does, to avoid pulling quoin's CLI dependency
+tree into a desktop bundle). Either way an install/removal by one tool is observed
+by the other.
+
+This formalizes the existing exports as a consumed contract: the CLI behavior in
+[FR-019](./FR-019-manage-plugin-registry.md) and the catalog assembly in
+[FR-007](./FR-007-assemble-module-roots.md) become reusable from a library import,
+not only the command line.
+
+## Behavior
+
+- The package entry point SHALL export `installPlugin`, `listPlugins`,
+  `removePlugin`, `parseSourceArg`, `loadCatalog`, and `filamentModulesDir`.
+- The exported operations SHALL read and write the same shared store paths as the
+  CLI, so an install or removal performed through the library is observable by the
+  CLI and vice versa.
+- The package SHALL treat a breaking change to this exported surface as a
+  semver-major change, so downstream consumers can pin against it.
+
+## Acceptance Criteria
+
+| ID          | Criteria                                                                                             | Verification           |
+| ----------- | ---------------------------------------------------------------------------------------------------- | ---------------------- |
+| FR-024-AC-1 | The package entry point exports the named plugin and catalog operations                              | Test (index.test.ts)   |
+| FR-024-AC-2 | A plugin installed through `installPlugin` is listed by `listPlugins` and assembled by `loadCatalog` | Test (index.test.ts)   |
+| FR-024-AC-3 | A library-performed install/removal targets the same shared store the CLI uses                       | Test (plugins.test.ts) |
+
+## Dependencies
+
+- **Upstream**: [StR-003](../stakeholder/StR-003-shared-catalog.md) shared
+  catalog; the CLI plugin operations [FR-019](./FR-019-manage-plugin-registry.md)
+  and catalog assembly [FR-007](./FR-007-assemble-module-roots.md) whose internals
+  this surface re-exports.
+- **Downstream**: filament-ide interoperates over the same shared store via
+  `@agent-ix/ts-plugin-kit` and these store conventions — rather than importing this
+  library — to install, list, remove, and load plugins
+  (`ix://agent-ix/filament-ide/FR-023`, `ix://agent-ix/filament-ide/FR-020`).
diff --git a/spec/spec.md b/spec/spec.md
index de66dfb..a0bc8b9 100644
--- a/spec/spec.md
+++ b/spec/spec.md
@@ -144,6 +144,7 @@ index; the files are authoritative.
 - [FR-017](./functional/FR-017-reconcile-default-modules.md) — reconcile the default module set into the shared store.
 - [FR-018](./functional/FR-018-map-plugin-sources.md) — map plugin source arguments to typed sources.
 - [FR-019](./functional/FR-019-manage-plugin-registry.md) — install, list, and remove plugins through the registry.
+- [FR-024](./functional/FR-024-plugin-catalog-library-api.md) — expose plugin and catalog operations as a stable library API.
 
 **Workflows**