diff --git a/packages/build/docs/interfaces/InputSpec.md b/packages/build/docs/interfaces/InputSpec.md
index 9372af45..b6de2c19 100644
--- a/packages/build/docs/interfaces/InputSpec.md
+++ b/packages/build/docs/interfaces/InputSpec.md
@@ -6,6 +6,19 @@ Describes a model input variable.
 
 ## Properties
 
+### inputId
+
+ `Optional` **inputId**: `string`
+
+The stable input identifier.  It is recommended to set this to a value (for example, a
+numeric string like what `plugin-config` uses) that is separate from `varName` and is
+stable between two versions of the model.  This way, if an input variable is renamed
+between two versions of the model, comparisons can still be performed between the two.
+If a distinct `inputId` is not available, plugins can infer one from `varName`, but
+note that this approach will be less resilient to renames.
+
+___
+
 ### varName
 
  **varName**: `string`
diff --git a/packages/build/src/_shared/model-spec.ts b/packages/build/src/_shared/model-spec.ts
index c5f7562b..f3fe5a86 100644
--- a/packages/build/src/_shared/model-spec.ts
+++ b/packages/build/src/_shared/model-spec.ts
@@ -4,6 +4,16 @@
  * Describes a model input variable.
  */
 export interface InputSpec {
+  /**
+   * The stable input identifier.  It is recommended to set this to a value (for example, a
+   * numeric string like what `plugin-config` uses) that is separate from `varName` and is
+   * stable between two versions of the model.  This way, if an input variable is renamed
+   * between two versions of the model, comparisons can still be performed between the two.
+   * If a distinct `inputId` is not available, plugins can infer one from `varName`, but
+   * note that this approach will be less resilient to renames.
+   */
+  inputId?: string
+
   /** The variable name (as used in the modeling tool). */
   varName: string
 
diff --git a/packages/plugin-config/src/context.ts b/packages/plugin-config/src/context.ts
index b418df62..8b572dce 100644
--- a/packages/plugin-config/src/context.ts
+++ b/packages/plugin-config/src/context.ts
@@ -69,7 +69,13 @@ export class ConfigContext {
     this.buildContext.writeStagedFile(srcDir, dstDir, filename, content)
   }
 
-  addInputVariable(inputVarName: string, defaultValue: number, minValue: number, maxValue: number): void {
+  addInputVariable(
+    inputId: string,
+    inputVarName: string,
+    defaultValue: number,
+    minValue: number,
+    maxValue: number
+  ): void {
     // We use the C name as the key to avoid redundant entries in cases where
     // the csv file refers to variables with different capitalization
     const varId = sdeNameForVensimVarName(inputVarName)
@@ -79,6 +85,7 @@ export class ConfigContext {
       console.error(`ERROR: Input variable ${inputVarName} was already added`)
     }
     this.inputSpecs.set(varId, {
+      inputId,
       varName: inputVarName,
       defaultValue,
       minValue,
diff --git a/packages/plugin-config/src/gen-inputs.ts b/packages/plugin-config/src/gen-inputs.ts
index 529dec79..9d723400 100644
--- a/packages/plugin-config/src/gen-inputs.ts
+++ b/packages/plugin-config/src/gen-inputs.ts
@@ -129,7 +129,7 @@ function inputSpecFromCsv(r: CsvRow, context: ConfigContext): InputSpec | undefi
       e += `default=${defaultValue} min=${minValue} max=${maxValue}`
       throw new Error(e)
     }
-    context.addInputVariable(varName, defaultValue, minValue, maxValue)
+    context.addInputVariable(inputId, varName, defaultValue, minValue, maxValue)
 
     const format = optionalString(r['format']) || '.0f'
 
@@ -179,7 +179,7 @@ function inputSpecFromCsv(r: CsvRow, context: ConfigContext): InputSpec | undefi
 
     const minValue = Math.min(offValue, onValue)
     const maxValue = Math.max(offValue, onValue)
-    context.addInputVariable(varName, defaultValue, minValue, maxValue)
+    context.addInputVariable(inputId, varName, defaultValue, minValue, maxValue)
 
     // The `controlled input ids` field dictates which rows are active
     // when this switch is on or off.  Examples of the format of this field:
diff --git a/packages/plugin-config/src/processor.spec.ts b/packages/plugin-config/src/processor.spec.ts
index 5c090e4a..0162f5f7 100644
--- a/packages/plugin-config/src/processor.spec.ts
+++ b/packages/plugin-config/src/processor.spec.ts
@@ -8,7 +8,7 @@ import { fileURLToPath } from 'url'
 import temp from 'temp'
 import { afterAll, beforeAll, describe, expect, it } from 'vitest'
 
-import type { BuildOptions, UserConfig } from '@sdeverywhere/build'
+import type { BuildOptions, ModelSpec, Plugin, UserConfig } from '@sdeverywhere/build'
 import { build } from '@sdeverywhere/build'
 
 import type { ConfigOptions } from './processor'
@@ -22,7 +22,10 @@ interface TestEnv {
   buildOptions: BuildOptions
 }
 
-async function prepareForBuild(optionsFunc: (corePkgDir: string) => ConfigOptions): Promise<TestEnv> {
+async function prepareForBuild(
+  optionsFunc: (corePkgDir: string) => ConfigOptions,
+  plugins: Plugin[] = []
+): Promise<TestEnv> {
   const baseTmpDir = await temp.mkdir('sde-plugin-config')
   const projDir = joinPath(baseTmpDir, 'proj')
   await mkdir(projDir)
@@ -32,7 +35,8 @@ async function prepareForBuild(optionsFunc: (corePkgDir: string) => ConfigOption
   const config: UserConfig = {
     rootDir: projDir,
     modelFiles: [],
-    modelSpec: configProcessor(optionsFunc(corePkgDir))
+    modelSpec: configProcessor(optionsFunc(corePkgDir)),
+    plugins
   }
 
   const buildOptions: BuildOptions = {
@@ -216,16 +220,53 @@ describe('configProcessor', () => {
   })
 
   it('should write to default directory structure if single out dir is provided', async () => {
+    let capturedModelSpec: ModelSpec
+    const plugin: Plugin = {
+      async preGenerate(_, modelSpec) {
+        capturedModelSpec = modelSpec
+      }
+    }
+
     const configDir = joinPath(__dirname, '__tests__', 'config1')
-    const testEnv = await prepareForBuild(corePkgDir => ({
-      config: configDir,
-      out: corePkgDir
-    }))
+    const testEnv = await prepareForBuild(
+      corePkgDir => ({
+        config: configDir,
+        out: corePkgDir
+      }),
+      [plugin]
+    )
     const result = await build('production', testEnv.buildOptions)
     if (result.isErr()) {
       throw new Error('Expected ok result but got: ' + result.error.message)
     }
 
+    expect(capturedModelSpec).toBeDefined()
+    expect(capturedModelSpec.inputs).toEqual([
+      {
+        inputId: '1',
+        varName: 'Input A',
+        defaultValue: 0,
+        minValue: -50,
+        maxValue: 50
+      },
+      {
+        inputId: '2',
+        varName: 'Input B',
+        defaultValue: 0,
+        minValue: -50,
+        maxValue: 50
+      },
+      {
+        inputId: '3',
+        varName: 'Input C',
+        defaultValue: 0,
+        minValue: 0,
+        maxValue: 1
+      }
+    ])
+    expect(capturedModelSpec.outputs).toEqual([{ varName: 'Var 1' }])
+    expect(capturedModelSpec.datFiles).toEqual(['../Data1.dat', '../Data2.dat'])
+
     const specJsonFile = joinPath(testEnv.projDir, 'sde-prep', 'spec.json')
     expect(await readFile(specJsonFile, 'utf8')).toEqual(specJson1)