fix: validate compaction config pairs

packages/compact/compact-basic/src/config.ts

@@ -248,17 +248,29 @@ function validatePolicy(
     assertNonNegativeInteger(`${name}.maxOverflowRetries`, maxOverflowRetries)
   }
 
-  const summarizationProvider = config.summarizationProvider
-  const summarizationModel = config.summarizationModel
-  if (summarizationProvider !== undefined && typeof summarizationProvider !== 'string') {
+  validateSummarizationPair(config, name)
+}
+
+/** Require one scope to omit, clear, or replace the summarization target as a pair. */
+function validateSummarizationPair(
+  config: CompactPolicyConfig | Record<string, unknown>,
+  name: string,
+): void {
+  const provider = config.summarizationProvider
+  const model = config.summarizationModel
+  if (provider !== undefined && typeof provider !== 'string') {
     throw new Error(`${name}.summarizationProvider must be a string`)
   }
-  if (summarizationModel !== undefined && typeof summarizationModel !== 'string') {
+  if (model !== undefined && typeof model !== 'string') {
     throw new Error(`${name}.summarizationModel must be a string`)
   }
-  if (((summarizationProvider ?? '').length === 0)
-    !== ((summarizationModel ?? '').length === 0)) {
-    throw new Error(`${name}: summarizationProvider and summarizationModel must both be empty or both be non-empty`)
+  if (provider === undefined && model === undefined) return
+  if (provider === undefined || model === undefined
+    || (provider.length === 0) !== (model.length === 0)) {
+    throw new Error(
+      `${name}: summarizationProvider and summarizationModel must be set together `
+      + 'as an empty or non-empty pair',
+    )
   }
 }
 

packages/compact/compact-basic/tests/compact-basic.spec.ts

@@ -308,6 +308,41 @@ describe('compact configuration and defaults', () => {
     })
   })
 
+  it('inherits, clears, and replaces the summarization target as a pair', () => {
+    const config = resolveConfig({
+      summarizationProvider: 'default-provider',
+      summarizationModel: 'default-model',
+      modelPolicies: [
+        { provider: 'inherit-provider', model: MODEL },
+        {
+          provider: 'clear-provider',
+          model: MODEL,
+          summarizationProvider: '',
+          summarizationModel: '',
+        },
+        {
+          provider: 'replace-provider',
+          model: MODEL,
+          summarizationProvider: 'replacement-provider',
+          summarizationModel: 'replacement-model',
+        },
+      ],
+    })
+
+    expect(resolveTargetPolicy(config, { provider: 'inherit-provider', model: MODEL }))
+      .toMatchObject({
+        summarizationProvider: 'default-provider',
+        summarizationModel: 'default-model',
+      })
+    expect(resolveTargetPolicy(config, { provider: 'clear-provider', model: MODEL }))
+      .toMatchObject({ summarizationProvider: '', summarizationModel: '' })
+    expect(resolveTargetPolicy(config, { provider: 'replace-provider', model: MODEL }))
+      .toMatchObject({
+        summarizationProvider: 'replacement-provider',
+        summarizationModel: 'replacement-model',
+      })
+  })
+
   it('validates common values and pressure-policy invariants', () => {
     const bad = [
       [{ maxTokens: 0 }, /maxTokens/],
@@ -316,8 +351,10 @@ describe('compact configuration and defaults', () => {
       [{ auto: 'yes' }, /auto must be a boolean/],
       [{ summarizationProvider: 1 }, /summarizationProvider must be a string/],
       [{ summarizationModel: 1 }, /summarizationModel must be a string/],
-      [{ summarizationProvider: MODEL }, /must both be empty or both be non-empty/],
-      [{ summarizationModel: MODEL }, /must both be empty or both be non-empty/],
+      [{ summarizationProvider: MODEL }, /must be set together/],
+      [{ summarizationModel: MODEL }, /must be set together/],
+      [{ summarizationProvider: '' }, /must be set together/],
+      [{ summarizationModel: '' }, /must be set together/],
       [{ thresholdRatio: 0 }, /number in \(0, 1\]/],
       [{ thresholdRatio: 1.1 }, /number in \(0, 1\]/],
       [{ retainRatio: 0.9 }, /retainRatio \(0.9\) must be less than the resolved thresholdRatio \(0.8\)/],
@@ -333,6 +370,16 @@ describe('compact configuration and defaults', () => {
       [{ modelPolicies: [{ provider: MODEL, model: 1 }] }, /model must be a non-empty string/],
       [{ modelPolicies: [{ provider: MODEL, model: '' }] }, /model must be a non-empty string/],
       [{ modelPolicies: [{ provider: MODEL, model: MODEL, summarizationProvider: 1 }] }, /summarizationProvider must be a string/],
+      [{
+        summarizationProvider: 'default-provider',
+        summarizationModel: 'default-model',
+        modelPolicies: [{ provider: MODEL, model: MODEL, summarizationModel: '' }],
+      }, /modelPolicies\[0\].*must be set together/],
+      [{
+        summarizationProvider: 'default-provider',
+        summarizationModel: 'default-model',
+        modelPolicies: [{ provider: MODEL, model: MODEL, summarizationProvider: '' }],
+      }, /modelPolicies\[0\].*must be set together/],
       [{ modelPolicies: [{ provider: MODEL, model: MODEL, retainRatio: 0.2, retainTokens: 100 }] }, /mutually exclusive/],
       [
         { modelPolicies: [{ provider: MODEL, model: MODEL, thresholdRatio: 0.1 }] },

packages/compact/compact-basic/tests/compact-loop-repro.spec.ts

@@ -133,7 +133,6 @@ async function harness(toolSteps: number): Promise<{ ctx: Context; compact: Repr
     auto: true,
     thresholdRatio: 0.5,
     retainTokens: 50,
-    summarizationModel: '',
     maxTokens: 8192,
     compactionRetries: 1,
   })

packages/compact/compact-basic/tests/loader-composition.spec.ts

@@ -85,7 +85,7 @@ describe('real Loader composition', () => {
     context = new Context()
     await expect(context.plugin(TokenMeterService, {
       contextWindow: 4096,
-    })).rejects.toThrow(/TokenMeterConfig: unknown key "contextWindow"/)
+    } as never)).rejects.toThrow(/TokenMeterConfig: unknown key "contextWindow"/)
   })
 
   it('rejects stale compact-basic config after Schemastery normalization', async () => {
@@ -110,4 +110,19 @@ describe('real Loader composition', () => {
       }],
     })).rejects.toThrow(/modelPolicies\[0\]: retainRatio \(0.2\).*thresholdRatio \(0.1\)/)
   })
+
+  it('rejects an incomplete model-policy summarization pair during plugin load', async () => {
+    context = new Context()
+    await context.plugin(LlmService)
+    await context.plugin(TokenMeterService)
+    await expect(context.plugin(BasicCompactService, {
+      summarizationProvider: 'default-provider',
+      summarizationModel: 'default-model',
+      modelPolicies: [{
+        provider: 'test-provider',
+        model: 'test-model',
+        summarizationModel: '',
+      }],
+    })).rejects.toThrow(/modelPolicies\[0\].*must be set together/)
+  })
 })