fix(host): restore the patched tools.register when the plugin unloads

createToolAttribution permanently replaced the global tools service's
register method and never undid it: after the plugin was disabled,
removed, or reloaded, later registrations kept running through the dead
hook's wrapper, which retained the live map and recorded into it.

The wrap now registers a fiber effect whose disposer peels every wrapper
this incarnation installed back to the true original, so the global
instance is left exactly as it was found. A guard keeps the restore
order-independent: a closure that finds a newer incarnation's wrapper
installed does nothing, letting that incarnation's own effect own the
cleanup. ctx.effect exists in every supported dsh version (cordis 4.0.1
since 0.1.0-rc.7).

Fixes #36

src/host/attribution.ts

@@ -16,7 +16,10 @@
  *   wraps that instance's `register` (once — an earlier wrapper of a previous
  *   hook incarnation is peeled back to the original, so a plugin reload
  *   re-wraps without stacking) to capture the reader at registration time
- *   into a live map.
+ *   into a live map. Every wrapper is undone when the plugin unloads: the
+ *   original `register` goes back on the instance, unless a newer hook
+ *   incarnation re-wrapped it first (that incarnation's own cleanup then
+ *   owns the restore).
  * - When the reader slot is missing, root-named, or this plugin's own (e.g.
  *   LOCAL-LINK plugins — dev installs via `dsh plugin add <path>` or
  *   npm/pnpm link — whose anonymous entrypoints make cordis fall back to the
@@ -155,8 +158,8 @@ interface ToolServiceLike {
 
 /**
  * Install the runtime-attribution hook on a cordis app context. The hook
- * rides the calling fiber's lifetime (`ctx.on` / `ctx.get`), so it is
- * disposed with the plugin.
+ * rides the calling fiber's lifetime (`ctx.on`, and an effect that restores
+ * every patched `register`), so it is disposed with the plugin.
  * @param ctx - the context the dsh-context plugin runs in; its fiber name is
  * excluded from attributions.
  */
@@ -165,6 +168,9 @@ export function createToolAttribution(ctx: Context): ToolAttribution {
   const wrapped = new WeakSet()
   const self = ctx.fiber.name
   let lastReader: Context | undefined
+  // Restore closures for every instance this incarnation patched, run by the
+  // unload effect below.
+  const patched: (() => void)[] = []
 
   const wrapInstance = (tools: unknown) => {
     if (!tools || typeof tools !== 'object' || wrapped.has(tools)) return
@@ -200,6 +206,9 @@ export function createToolAttribution(ctx: Context): ToolAttribution {
     }
     ;(wrappedRegister as { attributedOriginal?: unknown }).attributedOriginal = original
     instance.register = wrappedRegister
+    patched.push(() => {
+      if (instance.register === wrappedRegister) instance.register = original as typeof instance.register
+    })
   }
 
   ctx.on('internal/get', (reader, name, _error, next) => {
@@ -210,6 +219,15 @@ export function createToolAttribution(ctx: Context): ToolAttribution {
     return tools
   })
 
+  // Scope symmetry for the register patch: unloading peels every wrapper this
+  // incarnation installed back to the true original, so other plugins are
+  // never left running through a dead hook. A closure that finds a newer
+  // incarnation's wrapper installed does nothing — that incarnation's own
+  // effect then owns the restore.
+  ctx.effect(() => () => {
+    for (const restore of patched.splice(0)) restore()
+  }, 'tools.register attribution')
+
   // An instance provided before this plugin started is still wrapped so later
   // registrations on it are captured. The tools it already holds were
   // registered before this hook could observe them (boot-time third-party

tests/host/attribution.spec.ts

@@ -206,6 +206,76 @@ describe('createToolAttribution', () => {
     assert.equal(second.ownerOf('reload_tool'), 'provider-b', 'the fresh hook records the registration')
   })
 
+  test('unloading the hook plugin restores the original register', async () => {
+    const app = new Context()
+    const fake = { register(_definition?: unknown) { return () => {} } }
+    app.provide('tools', fake)
+    const original = fake.register
+    let attribution!: ToolAttribution
+    const fiber = app.plugin({
+      name: 'dsh-context',
+      apply(sub) {
+        attribution = createToolAttribution(sub)
+      },
+    })
+    await fiber
+    assert.notEqual(fake.register, original, 'the hook wrapped the instance at apply')
+    await fiber.dispose()
+    assert.equal(fake.register, original, 'unload put the original register back on the instance')
+    fake.register({ name: 'orphan_tool' })
+    assert.equal(attribution.ownerOf('orphan_tool'), undefined, 'no dead-hook recording after unload')
+  })
+
+  test('an unloaded older incarnation leaves a newer wrapper installed', async () => {
+    const app = new Context()
+    const fake = { register() { return () => {} } }
+    app.provide('tools', fake)
+    const original = fake.register
+    let second!: ToolAttribution
+    const older = app.plugin({ name: 'older-hook', apply(sub) { createToolAttribution(sub) } })
+    await older
+    assert.notEqual(fake.register, original, 'the first hook wrapped the instance')
+    const newer = app.plugin({ name: 'newer-hook', apply(sub) { second = createToolAttribution(sub) } })
+    await newer
+    assert.notEqual(fake.register, original, 'the newer incarnation re-wrapped the instance')
+    await older.dispose()
+    assert.notEqual(fake.register, original, 'the older disposer did not strip the newer wrapper')
+    await app.plugin({
+      name: 'provider-c',
+      apply(sub) {
+        ;((sub as any).tools as { register(def?: unknown): () => void }).register({ name: 'late_tool' })
+      },
+    })
+    assert.equal(second.ownerOf('late_tool'), 'provider-c', 'the surviving hook still records')
+    await newer.dispose()
+    assert.equal(fake.register, original, 'the newer disposer restores the true original')
+  })
+
+  test('unload then re-apply re-wraps the restored original without stacking', async () => {
+    const app = new Context()
+    let calls = 0
+    app.provide('tools', { register() { calls++; return () => {} } })
+    let attribution!: ToolAttribution
+    const first = app.plugin({ name: 'dsh-context', apply(sub) { createToolAttribution(sub) } })
+    await first
+    await first.dispose()
+    const second = app.plugin({
+      name: 'dsh-context',
+      apply(sub) {
+        attribution = createToolAttribution(sub)
+      },
+    })
+    await second
+    await app.plugin({
+      name: 'provider-d',
+      apply(sub) {
+        ;((sub as any).tools as { register(def?: unknown): () => void }).register({ name: 'reloaded_tool' })
+      },
+    })
+    assert.equal(calls, 1, 'the original register ran once, through one wrapper only')
+    assert.equal(attribution.ownerOf('reloaded_tool'), 'provider-d', 'the re-applied hook records the registration')
+  })
+
   test('tags boot-time tools whose providers predate the hook as unknown', () => {
     const app = new Context()
     const fake = {