Allow users to bypass Runtime Config API calls during function deploys (#8944)

* feat: introduce mode where function deploy to never call runtime config API.

* fix few issues

* run formatter

* style nits

* Handle missing credentials gracefully in internaltesting:functions:discover

Default to runtimeConfigApiEnabled=false when API check fails (e.g., no credentials)

* Update src/deploy/functions/prepare.ts

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

* Simplify runtime config loading implementation

- Remove maybeLoadCodebasesWithConfig function and inline logic
- Remove two-pass discovery strategy that had backward compatibility issues
- Simplify to a straightforward on/off switch controlled by experiment flag
- Remove unnecessary unit tests for the removed function
- Update internaltesting:functions:discover to use simplified approach

The experiment now serves as a migration flag:
- Enabled (default): Loads runtime config for backward compatibility
- Disabled: Skips runtime config entirely as part of deprecation path

* reformat

* Remove unused someEndpoint function from build.ts

This function was added during two-pass discovery implementation but is no longer needed

---------

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: taeold

src/commands/internaltesting-functions-discover.ts

@@ -6,6 +6,10 @@ import { normalizeAndValidate } from "../functions/projectConfig";
 import { getProjectAdminSdkConfigOrCached } from "../emulator/adminSdkConfig";
 import { needProjectId } from "../projectUtils";
 import { FirebaseError } from "../error";
+import * as ensureApiEnabled from "../ensureApiEnabled";
+import { runtimeconfigOrigin } from "../api";
+import * as experiments from "../experiments";
+import { getFunctionsConfig } from "../deploy/functions/prepareFunctionsUpload";
 
 export const command = new Command("internaltesting:functions:discover")
   .description("discover function triggers defined in the current project directory")
@@ -18,9 +22,35 @@ export const command = new Command("internaltesting:functions:discover")
         "Admin SDK config unexpectedly undefined - have you run firebase init?",
       );
     }
-    const builds = await loadCodebases(fnConfig, options, firebaseConfig, {
-      firebase: firebaseConfig,
-    });
-    logger.info(JSON.stringify(builds, null, 2));
-    return builds;
+
+    let runtimeConfig: Record<string, unknown> = { firebase: firebaseConfig };
+    const allowFunctionsConfig = experiments.isEnabled("dangerouslyAllowFunctionsConfig");
+
+    if (allowFunctionsConfig) {
+      try {
+        const runtimeConfigApiEnabled = await ensureApiEnabled.check(
+          projectId,
+          runtimeconfigOrigin(),
+          "runtimeconfig",
+          /* silent=*/ true,
+        );
+
+        if (runtimeConfigApiEnabled) {
+          runtimeConfig = { ...runtimeConfig, ...(await getFunctionsConfig(projectId)) };
+        }
+      } catch (err) {
+        logger.debug("Could not check Runtime Config API status, assuming disabled:", err);
+      }
+    }
+
+    const wantBuilds = await loadCodebases(
+      fnConfig,
+      options,
+      firebaseConfig,
+      runtimeConfig,
+      undefined, // no filters
+    );
+
+    logger.info(JSON.stringify(wantBuilds, null, 2));
+    return wantBuilds;
   });

src/deploy/functions/prepare.ts

@@ -10,6 +10,7 @@ import * as runtimes from "./runtimes";
 import * as supported from "./runtimes/supported";
 import * as validate from "./validate";
 import * as ensure from "./ensure";
+import * as experiments from "../../experiments";
 import {
   functionsOrigin,
   artifactRegistryDomain,
@@ -86,17 +87,18 @@ export async function prepare(
   // Get the Firebase Config, and set it on each function in the deployment.
   const firebaseConfig = await functionsConfig.getFirebaseConfig(options);
   context.firebaseConfig = firebaseConfig;
-  let runtimeConfig: Record<string, unknown> = { firebase: firebaseConfig };
-  if (checkAPIsEnabled[1]) {
-    // If runtime config API is enabled, load the runtime config.
-    const config = await getFunctionsConfig(projectId);
-    runtimeConfig = { ...runtimeConfig, ...config };
-    context.hasRuntimeConfig = Object.keys(config).length > 0;
-  }
 
   context.codebaseDeployEvents = {};
 
-  // ===Phase 1. Load codebases from source.
+  // ===Phase 1. Load codebases from source with optional runtime config.
+  let runtimeConfig: Record<string, unknown> = { firebase: firebaseConfig };
+  const allowFunctionsConfig = experiments.isEnabled("dangerouslyAllowFunctionsConfig");
+
+  // Load runtime config if experiment allows it and API is enabled
+  if (allowFunctionsConfig && checkAPIsEnabled[1]) {
+    runtimeConfig = { ...runtimeConfig, ...(await getFunctionsConfig(projectId)) };
+  }
+
   const wantBuilds = await loadCodebases(
     context.config,
     options,