diff --git a/applicationset/generators/pull_request.go b/applicationset/generators/pull_request.go
index 0eb74e4f85..019c0903d8 100644
--- a/applicationset/generators/pull_request.go
+++ b/applicationset/generators/pull_request.go
@@ -243,9 +243,9 @@ func (g *PullRequestGenerator) github(ctx context.Context, cfg *argoprojiov1alph
 		}
 
 		if g.enableGitHubAPIMetrics {
-			return pullrequest.NewGithubAppService(*auth, cfg.API, cfg.Owner, cfg.Repo, cfg.Labels, httpClient)
+			return pullrequest.NewGithubAppService(ctx, *auth, cfg.API, cfg.Owner, cfg.Repo, cfg.Labels, httpClient)
 		}
-		return pullrequest.NewGithubAppService(*auth, cfg.API, cfg.Owner, cfg.Repo, cfg.Labels)
+		return pullrequest.NewGithubAppService(ctx, *auth, cfg.API, cfg.Owner, cfg.Repo, cfg.Labels)
 	}
 
 	// always default to token, even if not set (public access)
diff --git a/applicationset/generators/scm_provider.go b/applicationset/generators/scm_provider.go
index b2f3e20cd3..9e7158ef8e 100644
--- a/applicationset/generators/scm_provider.go
+++ b/applicationset/generators/scm_provider.go
@@ -296,9 +296,9 @@ func (g *SCMProviderGenerator) githubProvider(ctx context.Context, github *argop
 		}
 
 		if g.enableGitHubAPIMetrics {
-			return scm_provider.NewGithubAppProviderFor(*auth, github.Organization, github.API, github.AllBranches, httpClient)
+			return scm_provider.NewGithubAppProviderFor(ctx, *auth, github.Organization, github.API, github.AllBranches, httpClient)
 		}
-		return scm_provider.NewGithubAppProviderFor(*auth, github.Organization, github.API, github.AllBranches)
+		return scm_provider.NewGithubAppProviderFor(ctx, *auth, github.Organization, github.API, github.AllBranches)
 	}
 
 	token, err := utils.GetSecretRef(ctx, g.client, github.TokenRef, applicationSetInfo.Namespace, g.tokenRefStrictMode)
diff --git a/applicationset/services/internal/github_app/client.go b/applicationset/services/internal/github_app/client.go
index 5ae5cf969b..98f621157e 100644
--- a/applicationset/services/internal/github_app/client.go
+++ b/applicationset/services/internal/github_app/client.go
@@ -1,6 +1,8 @@
 package github_app
 
 import (
+	"context"
+	"errors"
 	"fmt"
 	"net/http"
 
@@ -8,40 +10,65 @@ import (
 	"github.com/google/go-github/v69/github"
 
 	"github.com/argoproj/argo-cd/v3/applicationset/services/github_app_auth"
-	appsetutils "github.com/argoproj/argo-cd/v3/applicationset/utils"
+	"github.com/argoproj/argo-cd/v3/util/git"
 )
 
-func getOptionalHTTPClientAndTransport(optionalHTTPClient ...*http.Client) (*http.Client, http.RoundTripper) {
-	httpClient := appsetutils.GetOptionalHTTPClient(optionalHTTPClient...)
-	if len(optionalHTTPClient) > 0 && optionalHTTPClient[0] != nil && optionalHTTPClient[0].Transport != nil {
-		// will either use the provided custom httpClient and it's transport
-		return httpClient, optionalHTTPClient[0].Transport
+// getInstallationClient creates a new GitHub client with the specified installation ID.
+// It also returns a ghinstallation.Transport, which can be used for git requests.
+func getInstallationClient(g github_app_auth.Authentication, url string, httpClient ...*http.Client) (*github.Client, error) {
+	if g.InstallationId <= 0 {
+		return nil, errors.New("installation ID is required for github")
 	}
-	// or the default httpClient and transport
-	return httpClient, http.DefaultTransport
-}
 
-// Client builds a github client for the given app authentication.
-func Client(g github_app_auth.Authentication, url string, optionalHTTPClient ...*http.Client) (*github.Client, error) {
-	httpClient, transport := getOptionalHTTPClientAndTransport(optionalHTTPClient...)
+	// Use provided HTTP client's transport or default
+	var transport http.RoundTripper
+	if len(httpClient) > 0 && httpClient[0] != nil && httpClient[0].Transport != nil {
+		transport = httpClient[0].Transport
+	} else {
+		transport = http.DefaultTransport
+	}
 
-	rt, err := ghinstallation.New(transport, g.Id, g.InstallationId, []byte(g.PrivateKey))
+	itr, err := ghinstallation.New(transport, g.Id, g.InstallationId, []byte(g.PrivateKey))
 	if err != nil {
-		return nil, fmt.Errorf("failed to create github app install: %w", err)
+		return nil, fmt.Errorf("failed to create GitHub installation transport: %w", err)
 	}
+
 	if url == "" {
 		url = g.EnterpriseBaseURL
 	}
+
 	var client *github.Client
-	httpClient.Transport = rt
 	if url == "" {
-		client = github.NewClient(httpClient)
-	} else {
-		rt.BaseURL = url
-		client, err = github.NewClient(httpClient).WithEnterpriseURLs(url, url)
-		if err != nil {
-			return nil, fmt.Errorf("failed to create github enterprise client: %w", err)
-		}
+		client = github.NewClient(&http.Client{Transport: itr})
+		return client, nil
+	}
+
+	itr.BaseURL = url
+	client, err = github.NewClient(&http.Client{Transport: itr}).WithEnterpriseURLs(url, url)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create GitHub enterprise client: %w", err)
 	}
 	return client, nil
 }
+
+// Client builds a github client for the given app authentication.
+func Client(ctx context.Context, g github_app_auth.Authentication, url, org string, optionalHTTPClient ...*http.Client) (*github.Client, error) {
+	if url == "" {
+		url = g.EnterpriseBaseURL
+	}
+
+	// If an installation ID is already provided, use it directly.
+	if g.InstallationId != 0 {
+		return getInstallationClient(g, url, optionalHTTPClient...)
+	}
+
+	// Auto-discover installation ID using shared utility
+	// Pass optional HTTP client for metrics tracking
+	installationId, err := git.DiscoverGitHubAppInstallationID(ctx, g.Id, g.PrivateKey, url, org, optionalHTTPClient...)
+	if err != nil {
+		return nil, err
+	}
+
+	g.InstallationId = installationId
+	return getInstallationClient(g, url, optionalHTTPClient...)
+}
diff --git a/applicationset/services/pull_request/github_app.go b/applicationset/services/pull_request/github_app.go
index 2cc7858d92..2819e7cb33 100644
--- a/applicationset/services/pull_request/github_app.go
+++ b/applicationset/services/pull_request/github_app.go
@@ -1,6 +1,7 @@
 package pull_request
 
 import (
+	"context"
 	"net/http"
 
 	"github.com/argoproj/argo-cd/v3/applicationset/services/github_app_auth"
@@ -8,9 +9,9 @@ import (
 	appsetutils "github.com/argoproj/argo-cd/v3/applicationset/utils"
 )
 
-func NewGithubAppService(g github_app_auth.Authentication, url, owner, repo string, labels []string, optionalHTTPClient ...*http.Client) (PullRequestService, error) {
+func NewGithubAppService(ctx context.Context, g github_app_auth.Authentication, url, owner, repo string, labels []string, optionalHTTPClient ...*http.Client) (PullRequestService, error) {
 	httpClient := appsetutils.GetOptionalHTTPClient(optionalHTTPClient...)
-	client, err := github_app.Client(g, url, httpClient)
+	client, err := github_app.Client(ctx, g, url, owner, httpClient)
 	if err != nil {
 		return nil, err
 	}
diff --git a/applicationset/services/scm_provider/github_app.go b/applicationset/services/scm_provider/github_app.go
index f11fcb0783..3863480e9d 100644
--- a/applicationset/services/scm_provider/github_app.go
+++ b/applicationset/services/scm_provider/github_app.go
@@ -1,6 +1,7 @@
 package scm_provider
 
 import (
+	"context"
 	"net/http"
 
 	"github.com/argoproj/argo-cd/v3/applicationset/services/github_app_auth"
@@ -8,9 +9,9 @@ import (
 	appsetutils "github.com/argoproj/argo-cd/v3/applicationset/utils"
 )
 
-func NewGithubAppProviderFor(g github_app_auth.Authentication, organization string, url string, allBranches bool, optionalHTTPClient ...*http.Client) (*GithubProvider, error) {
+func NewGithubAppProviderFor(ctx context.Context, g github_app_auth.Authentication, organization string, url string, allBranches bool, optionalHTTPClient ...*http.Client) (*GithubProvider, error) {
 	httpClient := appsetutils.GetOptionalHTTPClient(optionalHTTPClient...)
-	client, err := github_app.Client(g, url, httpClient)
+	client, err := github_app.Client(ctx, g, url, organization, httpClient)
 	if err != nil {
 		return nil, err
 	}
diff --git a/cmd/argocd/commands/admin/repo.go b/cmd/argocd/commands/admin/repo.go
index e02ae6fcd2..0f6d6dbb49 100644
--- a/cmd/argocd/commands/admin/repo.go
+++ b/cmd/argocd/commands/admin/repo.go
@@ -77,6 +77,15 @@ func NewGenRepoSpecCommand() *cobra.Command {
   
   # Add a private HTTP OCI repository named 'stable'
   argocd admin repo generate-spec oci://helm-oci-registry.cn-zhangjiakou.cr.aliyuncs.com --type oci --name stable --username test --password test --insecure-oci-force-http
+
+  # Add a private Git repository on GitHub.com via GitHub App. github-app-installation-id is optional, if not provided, the installation id will be fetched from the GitHub API.
+  argocd admin repo generate-spec https://git.example.com/repos/repo --github-app-id 1 --github-app-installation-id 2 --github-app-private-key-path test.private-key.pem
+
+  # Add a private Git repository on GitHub Enterprise via GitHub App. github-app-installation-id is optional, if not provided, the installation id will be fetched from the GitHub API.
+  argocd admin repo generate-spec https://ghe.example.com/repos/repo --github-app-id 1 --github-app-installation-id 2 --github-app-private-key-path test.private-key.pem --github-app-enterprise-base-url https://ghe.example.com/api/v3
+
+  # Add a private Git repository on Google Cloud Sources via GCP service account credentials
+  argocd admin repo generate-spec https://source.developers.google.com/p/my-google-cloud-project/r/my-repo --gcp-service-account-key-path service-account-key.json
 `
 
 	command := &cobra.Command{
diff --git a/cmd/argocd/commands/repo.go b/cmd/argocd/commands/repo.go
index e3786cbb8e..8f4bcc1388 100644
--- a/cmd/argocd/commands/repo.go
+++ b/cmd/argocd/commands/repo.go
@@ -94,10 +94,10 @@ func NewRepoAddCommand(clientOpts *argocdclient.ClientOptions) *cobra.Command {
   # Add a private HTTP OCI repository named 'stable'
   argocd repo add oci://helm-oci-registry.cn-zhangjiakou.cr.aliyuncs.com --type oci --name stable --username test --password test --insecure-oci-force-http
 
-  # Add a private Git repository on GitHub.com via GitHub App
+  # Add a private Git repository on GitHub.com via GitHub App. github-app-installation-id is optional, if not provided, the installation id will be fetched from the GitHub API.
   argocd repo add https://git.example.com/repos/repo --github-app-id 1 --github-app-installation-id 2 --github-app-private-key-path test.private-key.pem
 
-  # Add a private Git repository on GitHub Enterprise via GitHub App
+  # Add a private Git repository on GitHub Enterprise via GitHub App. github-app-installation-id is optional, if not provided, the installation id will be fetched from the GitHub API.
   argocd repo add https://ghe.example.com/repos/repo --github-app-id 1 --github-app-installation-id 2 --github-app-private-key-path test.private-key.pem --github-app-enterprise-base-url https://ghe.example.com/api/v3
 
   # Add a private Git repository on Google Cloud Sources via GCP service account credentials
diff --git a/cmd/argocd/commands/repocreds.go b/cmd/argocd/commands/repocreds.go
index 778b5be008..ed6892f857 100644
--- a/cmd/argocd/commands/repocreds.go
+++ b/cmd/argocd/commands/repocreds.go
@@ -72,10 +72,10 @@ func NewRepoCredsAddCommand(clientOpts *argocdclient.ClientOptions) *cobra.Comma
   # Add credentials with SSH private key authentication to use for all repositories under ssh://git@git.example.com/repos
   argocd repocreds add ssh://git@git.example.com/repos/ --ssh-private-key-path ~/.ssh/id_rsa
 
-  # Add credentials with GitHub App authentication to use for all repositories under https://github.com/repos
+  # Add credentials with GitHub App authentication to use for all repositories under https://github.com/repos. github-app-installation-id is optional, if not provided, the installation id will be fetched from the GitHub API.
   argocd repocreds add https://github.com/repos/ --github-app-id 1 --github-app-installation-id 2 --github-app-private-key-path test.private-key.pem
 
-  # Add credentials with GitHub App authentication to use for all repositories under https://ghe.example.com/repos
+  # Add credentials with GitHub App authentication to use for all repositories under https://ghe.example.com/repos. github-app-installation-id is optional, if not provided, the installation id will be fetched from the GitHub API.
   argocd repocreds add https://ghe.example.com/repos/ --github-app-id 1 --github-app-installation-id 2 --github-app-private-key-path test.private-key.pem --github-app-enterprise-base-url https://ghe.example.com/api/v3
 
   # Add credentials with helm oci registry so that these oci registry urls do not need to be added as repos individually.
@@ -191,7 +191,7 @@ func NewRepoCredsAddCommand(clientOpts *argocdclient.ClientOptions) *cobra.Comma
 	command.Flags().StringVar(&tlsClientCertPath, "tls-client-cert-path", "", "path to the TLS client cert (must be PEM format)")
 	command.Flags().StringVar(&tlsClientCertKeyPath, "tls-client-cert-key-path", "", "path to the TLS client cert's key (must be PEM format)")
 	command.Flags().Int64Var(&repo.GithubAppId, "github-app-id", 0, "id of the GitHub Application")
-	command.Flags().Int64Var(&repo.GithubAppInstallationId, "github-app-installation-id", 0, "installation id of the GitHub Application")
+	command.Flags().Int64Var(&repo.GithubAppInstallationId, "github-app-installation-id", 0, "installation id of the GitHub Application (optional, will be auto-discovered if not provided)")
 	command.Flags().StringVar(&githubAppPrivateKeyPath, "github-app-private-key-path", "", "private key of the GitHub Application")
 	command.Flags().StringVar(&repo.GitHubAppEnterpriseBaseURL, "github-app-enterprise-base-url", "", "base url to use when using GitHub Enterprise (e.g. https://ghe.example.com/api/v3")
 	command.Flags().BoolVar(&upsert, "upsert", false, "Override an existing repository with the same name even if the spec differs")
diff --git a/cmd/util/repo.go b/cmd/util/repo.go
index fdf87d91e3..ee105758f4 100644
--- a/cmd/util/repo.go
+++ b/cmd/util/repo.go
@@ -45,7 +45,7 @@ func AddRepoFlags(command *cobra.Command, opts *RepoOptions) {
 	command.Flags().BoolVar(&opts.EnableLfs, "enable-lfs", false, "enable git-lfs (Large File Support) on this repository")
 	command.Flags().BoolVar(&opts.EnableOci, "enable-oci", false, "enable helm-oci (Helm OCI-Based Repository) (only valid for helm type repositories)")
 	command.Flags().Int64Var(&opts.GithubAppId, "github-app-id", 0, "id of the GitHub Application")
-	command.Flags().Int64Var(&opts.GithubAppInstallationId, "github-app-installation-id", 0, "installation id of the GitHub Application")
+	command.Flags().Int64Var(&opts.GithubAppInstallationId, "github-app-installation-id", 0, "installation id of the GitHub Application (optional, will be auto-discovered if not provided)")
 	command.Flags().StringVar(&opts.GithubAppPrivateKeyPath, "github-app-private-key-path", "", "private key of the GitHub Application")
 	command.Flags().StringVar(&opts.GitHubAppEnterpriseBaseURL, "github-app-enterprise-base-url", "", "base url to use when using GitHub Enterprise (e.g. https://ghe.example.com/api/v3")
 	command.Flags().StringVar(&opts.Proxy, "proxy", "", "use proxy to access repository")
diff --git a/commitserver/commit/credentialtypehelper.go b/commitserver/commit/credentialtypehelper.go
index 2eea0a885b..ad2bea7e0c 100644
--- a/commitserver/commit/credentialtypehelper.go
+++ b/commitserver/commit/credentialtypehelper.go
@@ -13,7 +13,7 @@ func getCredentialType(repo *v1alpha1.Repository) string {
 	if repo.SSHPrivateKey != "" {
 		return "ssh"
 	}
-	if repo.GithubAppPrivateKey != "" && repo.GithubAppId != 0 && repo.GithubAppInstallationId != 0 {
+	if repo.GithubAppPrivateKey != "" && repo.GithubAppId != 0 { // Promoter MVP: remove github-app-installation-id check since it is no longer a required field
 		return "github-app"
 	}
 	if repo.GCPServiceAccountKey != "" {
diff --git a/docs/user-guide/commands/argocd_admin_repo_generate-spec.md b/docs/user-guide/commands/argocd_admin_repo_generate-spec.md
index 925ba22621..53e0722d41 100644
--- a/docs/user-guide/commands/argocd_admin_repo_generate-spec.md
+++ b/docs/user-guide/commands/argocd_admin_repo_generate-spec.md
@@ -45,6 +45,15 @@ argocd admin repo generate-spec REPOURL [flags]
   # Add a private HTTP OCI repository named 'stable'
   argocd admin repo generate-spec oci://helm-oci-registry.cn-zhangjiakou.cr.aliyuncs.com --type oci --name stable --username test --password test --insecure-oci-force-http
 
+  # Add a private Git repository on GitHub.com via GitHub App. github-app-installation-id is optional, if not provided, the installation id will be fetched from the GitHub API.
+  argocd admin repo generate-spec https://git.example.com/repos/repo --github-app-id 1 --github-app-installation-id 2 --github-app-private-key-path test.private-key.pem
+
+  # Add a private Git repository on GitHub Enterprise via GitHub App. github-app-installation-id is optional, if not provided, the installation id will be fetched from the GitHub API.
+  argocd admin repo generate-spec https://ghe.example.com/repos/repo --github-app-id 1 --github-app-installation-id 2 --github-app-private-key-path test.private-key.pem --github-app-enterprise-base-url https://ghe.example.com/api/v3
+
+  # Add a private Git repository on Google Cloud Sources via GCP service account credentials
+  argocd admin repo generate-spec https://source.developers.google.com/p/my-google-cloud-project/r/my-repo --gcp-service-account-key-path service-account-key.json
+
 ```
 
 ### Options
@@ -58,7 +67,7 @@ argocd admin repo generate-spec REPOURL [flags]
       --gcp-service-account-key-path string     service account key for the Google Cloud Platform
       --github-app-enterprise-base-url string   base url to use when using GitHub Enterprise (e.g. https://ghe.example.com/api/v3
       --github-app-id int                       id of the GitHub Application
-      --github-app-installation-id int          installation id of the GitHub Application
+      --github-app-installation-id int          installation id of the GitHub Application (optional, will be auto-discovered if not provided)
       --github-app-private-key-path string      private key of the GitHub Application
   -h, --help                                    help for generate-spec
       --insecure-ignore-host-key                disables SSH strict host key checking (deprecated, use --insecure-skip-server-verification instead)
diff --git a/docs/user-guide/commands/argocd_repo_add.md b/docs/user-guide/commands/argocd_repo_add.md
index 87a51c81f3..3061a3105c 100644
--- a/docs/user-guide/commands/argocd_repo_add.md
+++ b/docs/user-guide/commands/argocd_repo_add.md
@@ -47,10 +47,10 @@ argocd repo add REPOURL [flags]
   # Add a private HTTP OCI repository named 'stable'
   argocd repo add oci://helm-oci-registry.cn-zhangjiakou.cr.aliyuncs.com --type oci --name stable --username test --password test --insecure-oci-force-http
 
-  # Add a private Git repository on GitHub.com via GitHub App
+  # Add a private Git repository on GitHub.com via GitHub App. github-app-installation-id is optional, if not provided, the installation id will be fetched from the GitHub API.
   argocd repo add https://git.example.com/repos/repo --github-app-id 1 --github-app-installation-id 2 --github-app-private-key-path test.private-key.pem
 
-  # Add a private Git repository on GitHub Enterprise via GitHub App
+  # Add a private Git repository on GitHub Enterprise via GitHub App. github-app-installation-id is optional, if not provided, the installation id will be fetched from the GitHub API.
   argocd repo add https://ghe.example.com/repos/repo --github-app-id 1 --github-app-installation-id 2 --github-app-private-key-path test.private-key.pem --github-app-enterprise-base-url https://ghe.example.com/api/v3
 
   # Add a private Git repository on Google Cloud Sources via GCP service account credentials
@@ -69,7 +69,7 @@ argocd repo add REPOURL [flags]
       --gcp-service-account-key-path string     service account key for the Google Cloud Platform
       --github-app-enterprise-base-url string   base url to use when using GitHub Enterprise (e.g. https://ghe.example.com/api/v3
       --github-app-id int                       id of the GitHub Application
-      --github-app-installation-id int          installation id of the GitHub Application
+      --github-app-installation-id int          installation id of the GitHub Application (optional, will be auto-discovered if not provided)
       --github-app-private-key-path string      private key of the GitHub Application
   -h, --help                                    help for add
       --insecure-ignore-host-key                disables SSH strict host key checking (deprecated, use --insecure-skip-server-verification instead)
diff --git a/docs/user-guide/commands/argocd_repocreds_add.md b/docs/user-guide/commands/argocd_repocreds_add.md
index 5fcc0fa614..0b67135d99 100644
--- a/docs/user-guide/commands/argocd_repocreds_add.md
+++ b/docs/user-guide/commands/argocd_repocreds_add.md
@@ -20,10 +20,10 @@ argocd repocreds add REPOURL [flags]
   # Add credentials with SSH private key authentication to use for all repositories under ssh://git@git.example.com/repos
   argocd repocreds add ssh://git@git.example.com/repos/ --ssh-private-key-path ~/.ssh/id_rsa
 
-  # Add credentials with GitHub App authentication to use for all repositories under https://github.com/repos
+  # Add credentials with GitHub App authentication to use for all repositories under https://github.com/repos. github-app-installation-id is optional, if not provided, the installation id will be fetched from the GitHub API.
   argocd repocreds add https://github.com/repos/ --github-app-id 1 --github-app-installation-id 2 --github-app-private-key-path test.private-key.pem
 
-  # Add credentials with GitHub App authentication to use for all repositories under https://ghe.example.com/repos
+  # Add credentials with GitHub App authentication to use for all repositories under https://ghe.example.com/repos. github-app-installation-id is optional, if not provided, the installation id will be fetched from the GitHub API.
   argocd repocreds add https://ghe.example.com/repos/ --github-app-id 1 --github-app-installation-id 2 --github-app-private-key-path test.private-key.pem --github-app-enterprise-base-url https://ghe.example.com/api/v3
 
   # Add credentials with helm oci registry so that these oci registry urls do not need to be added as repos individually.
@@ -43,7 +43,7 @@ argocd repocreds add REPOURL [flags]
       --gcp-service-account-key-path string     service account key for the Google Cloud Platform
       --github-app-enterprise-base-url string   base url to use when using GitHub Enterprise (e.g. https://ghe.example.com/api/v3
       --github-app-id int                       id of the GitHub Application
-      --github-app-installation-id int          installation id of the GitHub Application
+      --github-app-installation-id int          installation id of the GitHub Application (optional, will be auto-discovered if not provided)
       --github-app-private-key-path string      private key of the GitHub Application
   -h, --help                                    help for add
       --password string                         password to the repository
diff --git a/docs/user-guide/private-repositories.md b/docs/user-guide/private-repositories.md
index cc11b7a977..483d8a15b5 100644
--- a/docs/user-guide/private-repositories.md
+++ b/docs/user-guide/private-repositories.md
@@ -122,13 +122,16 @@ argocd repo add https://github.com/argoproj/argocd-example-apps.git --github-app
 > [!NOTE]
 > To add a private Git repository on GitHub Enterprise using the CLI add `--github-app-enterprise-base-url https://ghe.example.com/api/v3` flag.
 
+> [!NOTE]
+> The `--github-app-installation-id` flag is optional. If omitted, Argo CD will automatically discover the installation ID based on the repository's organization.
+
 Using the UI:
 
 1. Navigate to `Settings/Repositories`
 
     ![connect repo overview](../assets/repo-add-overview.png)
 
-2. Click `Connect Repo using GitHub App` button, choose type: `GitHub` or `GitHub Enterprise`, enter the URL, App Id, Installation Id, and the app's private key.
+2. Click `Connect Repo using GitHub App` button, choose type: `GitHub` or `GitHub Enterprise`, enter the URL, App Id, Installation Id (optional), and the app's private key.
 
 > [!NOTE]
 > Enter the GitHub Enterprise Base URL for type `GitHub Enterprise`.
diff --git a/docs/user-guide/source-hydrator.md b/docs/user-guide/source-hydrator.md
index 670ec68112..a6f8a78092 100644
--- a/docs/user-guide/source-hydrator.md
+++ b/docs/user-guide/source-hydrator.md
@@ -62,7 +62,8 @@ stringData:
   url: "https://github.com/<your org or user>/<your repo>"
   type: "git"
   githubAppID: "<your app ID here>"
-  githubAppInstallationID: "<your installation ID here>"
+  # githubAppInstallationID is optional and will be auto-discovered if omitted
+  githubAppInstallationID: "<your installation ID here>" # Optional
   githubAppPrivateKey: |
     <your private key here>
 ---
@@ -78,7 +79,8 @@ stringData:
   url: "https://github.com/<your org or user>/<your repo>"
   type: "git"
   githubAppID: "<your app ID here>"
-  githubAppInstallationID: "<your installation ID here>"
+  # githubAppInstallationID is optional and will be auto-discovered if omitted
+  githubAppInstallationID: "<your installation ID here>"  # Optional
   githubAppPrivateKey: |
     <your private key here>
 ```
diff --git a/pkg/apis/application/v1alpha1/repository_types.go b/pkg/apis/application/v1alpha1/repository_types.go
index 71a311f7ff..8366064a18 100644
--- a/pkg/apis/application/v1alpha1/repository_types.go
+++ b/pkg/apis/application/v1alpha1/repository_types.go
@@ -1,9 +1,11 @@
 package v1alpha1
 
 import (
+	"context"
 	"fmt"
 	"net/url"
 	"strings"
+	"time"
 
 	"github.com/argoproj/argo-cd/v3/util/oci"
 
@@ -239,8 +241,33 @@ func (repo *Repository) GetGitCreds(store git.CredsStore) git.Creds {
 	if repo.SSHPrivateKey != "" {
 		return git.NewSSHCreds(repo.SSHPrivateKey, getCAPath(repo.Repo), repo.IsInsecure(), repo.Proxy)
 	}
-	if repo.GithubAppPrivateKey != "" && repo.GithubAppId != 0 && repo.GithubAppInstallationId != 0 {
-		return git.NewGitHubAppCreds(repo.GithubAppId, repo.GithubAppInstallationId, repo.GithubAppPrivateKey, repo.GitHubAppEnterpriseBaseURL, repo.TLSClientCertData, repo.TLSClientCertKey, repo.IsInsecure(), repo.Proxy, repo.NoProxy, store)
+	if repo.GithubAppPrivateKey != "" && repo.GithubAppId != 0 { // Promoter MVP: remove github-app-installation-id check since it is no longer a required field
+		installationId := repo.GithubAppInstallationId
+
+		// Auto-discover installation ID if not provided
+		if installationId == 0 {
+			org, err := git.ExtractOrgFromRepoURL(repo.Repo)
+			if err != nil {
+				log.Warnf("Failed to extract organization from repository URL %s for GitHub App auto-discovery: %v", repo.Repo, err)
+				return git.NopCreds{}
+			}
+			if org != "" {
+				ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
+				defer cancel()
+
+				discoveredId, err := git.DiscoverGitHubAppInstallationID(ctx, repo.GithubAppId, repo.GithubAppPrivateKey, repo.GitHubAppEnterpriseBaseURL, org)
+				if err != nil {
+					log.Warnf("Failed to auto-discover GitHub App installation ID for org %s: %v. Proceeding with installation ID 0.", org, err)
+				} else {
+					log.Infof("Auto-discovered GitHub App installation ID %d for org %s", discoveredId, org)
+					installationId = discoveredId
+				}
+			} else {
+				log.Warnf("Could not extract organization from repository URL %s for GitHub App auto-discovery", repo.Repo)
+			}
+		}
+
+		return git.NewGitHubAppCreds(repo.GithubAppId, installationId, repo.GithubAppPrivateKey, repo.GitHubAppEnterpriseBaseURL, repo.TLSClientCertData, repo.TLSClientCertKey, repo.IsInsecure(), repo.Proxy, repo.NoProxy, store)
 	}
 	if repo.GCPServiceAccountKey != "" {
 		return git.NewGoogleCloudCreds(repo.GCPServiceAccountKey, store)
diff --git a/ui/src/app/settings/components/repos-list/repos-list.tsx b/ui/src/app/settings/components/repos-list/repos-list.tsx
index 5a2834a493..478838e618 100644
--- a/ui/src/app/settings/components/repos-list/repos-list.tsx
+++ b/ui/src/app/settings/components/repos-list/repos-list.tsx
@@ -217,7 +217,6 @@ export const ReposList = ({match, location}: RouteComponentProps) => {
                 return {
                     url: (!githubAppValues.url && 'Repository URL is required') || (credsTemplate && !isHTTPOrHTTPSUrl(githubAppValues.url) && 'Not a valid HTTP/HTTPS URL'),
                     githubAppId: !githubAppValues.githubAppId && 'GitHub App ID is required',
-                    githubAppInstallationId: !githubAppValues.githubAppInstallationId && 'GitHub App installation ID is required',
                     githubAppPrivateKey: !githubAppValues.githubAppPrivateKey && 'GitHub App private Key is required'
                 };
             case ConnectionMethod.GOOGLECLOUD:
diff --git a/util/git/creds.go b/util/git/creds.go
index 0a7640b060..130f6df7d2 100644
--- a/util/git/creds.go
+++ b/util/git/creds.go
@@ -9,13 +9,16 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"net"
 	"net/http"
 	"net/url"
 	"os"
 	"strconv"
 	"strings"
+	"sync"
 	"time"
 
+	giturls "github.com/chainguard-dev/git-urls"
 	"github.com/google/go-github/v69/github"
 
 	"golang.org/x/oauth2"
@@ -43,6 +46,10 @@ var (
 
 	// In memory cache for storing Azure tokens
 	azureTokenCache *gocache.Cache
+
+	// installationIdCache caches installation IDs for organizations to avoid redundant API calls.
+	githubInstallationIdCache      *gocache.Cache
+	githubInstallationIdCacheMutex sync.RWMutex // For bulk API call coordination
 )
 
 const (
@@ -66,6 +73,7 @@ func init() {
 	// oauth2.TokenSource handles fetching new Tokens once they are expired. The oauth2.TokenSource itself does not expire.
 	googleCloudTokenSource = gocache.New(gocache.NoExpiration, 0)
 	azureTokenCache = gocache.New(gocache.NoExpiration, 0)
+	githubInstallationIdCache = gocache.New(60*time.Minute, 60*time.Minute)
 }
 
 type NoopCredsStore struct{}
@@ -576,6 +584,199 @@ func (g GitHubAppCreds) GetClientCertKey() string {
 	return g.clientCertKey
 }
 
+// GitHub App installation discovery cache and helper
+
+// DiscoverGitHubAppInstallationID discovers the GitHub App installation ID for a given organization.
+// It queries the GitHub API to list all installations for the app and returns the installation ID
+// for the matching organization. Results are cached to avoid redundant API calls.
+// An optional HTTP client can be provided for custom transport (e.g., for metrics tracking).
+func DiscoverGitHubAppInstallationID(ctx context.Context, appId int64, privateKey, enterpriseBaseURL, org string, httpClient ...*http.Client) (int64, error) {
+	domain, err := domainFromBaseURL(enterpriseBaseURL)
+	if err != nil {
+		return 0, fmt.Errorf("failed to get domain from base URL: %w", err)
+	}
+	org = strings.ToLower(org)
+	// Check cache first
+	cacheKey := fmt.Sprintf("%s:%s:%d", strings.ToLower(org), domain, appId)
+	if id, found := githubInstallationIdCache.Get(cacheKey); found {
+		return id.(int64), nil
+	}
+
+	// Use provided HTTP client or default
+	var transport http.RoundTripper
+	if len(httpClient) > 0 && httpClient[0] != nil && httpClient[0].Transport != nil {
+		transport = httpClient[0].Transport
+	} else {
+		transport = http.DefaultTransport
+	}
+
+	// Create GitHub App transport
+	rt, err := ghinstallation.NewAppsTransport(transport, appId, []byte(privateKey))
+	if err != nil {
+		return 0, fmt.Errorf("failed to create GitHub app transport: %w", err)
+	}
+
+	if enterpriseBaseURL != "" {
+		rt.BaseURL = enterpriseBaseURL
+	}
+
+	// Create GitHub client
+	var client *github.Client
+	clientTransport := &http.Client{Transport: rt}
+	if enterpriseBaseURL == "" {
+		client = github.NewClient(clientTransport)
+	} else {
+		client, err = github.NewClient(clientTransport).WithEnterpriseURLs(enterpriseBaseURL, enterpriseBaseURL)
+		if err != nil {
+			return 0, fmt.Errorf("failed to create GitHub enterprise client: %w", err)
+		}
+	}
+
+	// List all installations and cache them
+	var allInstallations []*github.Installation
+	opts := &github.ListOptions{PerPage: 100}
+
+	// Lock for the entire loop to avoid multiple concurrent API calls on startup
+	githubInstallationIdCacheMutex.Lock()
+	defer githubInstallationIdCacheMutex.Unlock()
+
+	// Check cache again inside the write lock in case another goroutine already fetched it
+	if id, found := githubInstallationIdCache.Get(cacheKey); found {
+		return id.(int64), nil
+	}
+
+	for {
+		installations, resp, err := client.Apps.ListInstallations(ctx, opts)
+		if err != nil {
+			return 0, fmt.Errorf("failed to list installations: %w", err)
+		}
+
+		allInstallations = append(allInstallations, installations...)
+
+		if resp.NextPage == 0 {
+			break
+		}
+		opts.Page = resp.NextPage
+	}
+
+	// Cache all installation IDs
+	for _, installation := range allInstallations {
+		if installation.Account != nil && installation.Account.Login != nil && installation.ID != nil {
+			githubInstallationIdCache.Set(cacheKey, *installation.ID, gocache.DefaultExpiration)
+		}
+	}
+
+	// Return the installation ID for the requested org
+	if id, found := githubInstallationIdCache.Get(cacheKey); found {
+		return id.(int64), nil
+	}
+	return 0, fmt.Errorf("installation not found for org: %s", org)
+}
+
+// domainFromBaseURL extracts the host (domain) from the given GitHub base URL.
+// Supports HTTP(S), SSH URLs, and git@host:org/repo forms.
+// Returns an error if a domain cannot be extracted.
+func domainFromBaseURL(baseURL string) (string, error) {
+	if baseURL == "" {
+		return "github.com", nil
+	}
+
+	// --- 1. SSH-style Git URL: git@github.com:org/repo.git ---
+	if strings.Contains(baseURL, "@") && strings.Contains(baseURL, ":") && !strings.Contains(baseURL, "://") {
+		parts := strings.SplitN(baseURL, "@", 2)
+		right := parts[len(parts)-1]             // github.com:org/repo
+		host := strings.SplitN(right, ":", 2)[0] // github.com
+		if host != "" {
+			return host, nil
+		}
+		return "", fmt.Errorf("failed to extract host from SSH-style URL: %q", baseURL)
+	}
+
+	// --- 2. Ensure scheme so url.Parse works ---
+	if !strings.HasPrefix(baseURL, "http://") &&
+		!strings.HasPrefix(baseURL, "https://") &&
+		!strings.HasPrefix(baseURL, "ssh://") {
+		baseURL = "https://" + baseURL
+	}
+
+	// --- 3. Standard URL parse ---
+	parsed, err := url.Parse(baseURL)
+	if err != nil {
+		return "", fmt.Errorf("failed to parse URL %q: %w", baseURL, err)
+	}
+	if parsed.Host == "" {
+		return "", fmt.Errorf("URL %q parsed but host is empty", baseURL)
+	}
+
+	host := parsed.Host
+	if h, _, err := net.SplitHostPort(host); err == nil {
+		host = h
+	}
+	return host, nil
+}
+
+// ExtractOrgFromRepoURL extracts the organization/owner name from a GitHub repository URL.
+// Supports formats:
+//   - HTTPS: https://github.com/org/repo.git
+//   - SSH: git@github.com:org/repo.git
+//   - SSH with port: git@github.com:22/org/repo.git or ssh://git@github.com:22/org/repo.git
+func ExtractOrgFromRepoURL(repoURL string) (string, error) {
+	if repoURL == "" {
+		return "", errors.New("repo URL is empty")
+	}
+
+	// Handle edge case: ssh://git@host:org/repo (malformed but used in practice)
+	// This format mixes ssh:// prefix with colon notation instead of using a slash.
+	// Convert it to git@host:org/repo which git-urls can parse correctly.
+	// We distinguish this from the valid ssh://git@host:22/org/repo (with port number).
+	if strings.HasPrefix(repoURL, "ssh://git@") {
+		remainder := strings.TrimPrefix(repoURL, "ssh://")
+		if colonIdx := strings.Index(remainder, ":"); colonIdx != -1 {
+			afterColon := remainder[colonIdx+1:]
+			slashIdx := strings.Index(afterColon, "/")
+
+			// Check if what follows the colon is a port number
+			isPort := false
+			if slashIdx > 0 {
+				if _, err := strconv.Atoi(afterColon[:slashIdx]); err == nil {
+					isPort = true
+				}
+			}
+
+			// If not a port, it's the malformed format - strip ssh:// prefix
+			if !isPort && slashIdx != 0 {
+				repoURL = remainder
+			}
+		}
+	}
+
+	// Use git-urls library to parse all Git URL formats
+	parsed, err := giturls.Parse(repoURL)
+	if err != nil {
+		return "", fmt.Errorf("failed to parse repository URL %q: %w", repoURL, err)
+	}
+
+	// Clean the path: remove leading/trailing slashes and .git suffix
+	path := strings.Trim(parsed.Path, "/")
+	path = strings.TrimSuffix(path, ".git")
+
+	if path == "" {
+		return "", fmt.Errorf("repository URL %q does not contain a path", repoURL)
+	}
+
+	// Extract the first path component (organization/owner)
+	// Path format is typically "org/repo" or "org/repo/subpath"
+	if idx := strings.Index(path, "/"); idx > 0 {
+		org := path[:idx]
+		// Normalize to lowercase for case-insensitive comparison
+		return strings.ToLower(org), nil
+	}
+
+	// If there's no slash, the entire path might be just the org (unusual but handle it)
+	// This would fail validation later, but let's return it
+	return "", fmt.Errorf("could not extract organization from repository URL %q: path %q does not contain org/repo format", repoURL, path)
+}
+
 var _ Creds = GoogleCloudCreds{}
 
 // GoogleCloudCreds to authenticate to Google Cloud Source repositories
diff --git a/util/git/creds_test.go b/util/git/creds_test.go
index b34927e4ad..f8b0b1cd30 100644
--- a/util/git/creds_test.go
+++ b/util/git/creds_test.go
@@ -1,8 +1,12 @@
 package git
 
 import (
+	"context"
 	"encoding/base64"
+	"encoding/json"
 	"fmt"
+	"net/http"
+	"net/http/httptest"
 	"os"
 	"path"
 	"regexp"
@@ -515,3 +519,132 @@ func TestAzureWorkloadIdentityCreds_ReuseTokenIfExistingIsNotExpired(t *testing.
 func resetAzureTokenCache() {
 	azureTokenCache = gocache.New(gocache.NoExpiration, 0)
 }
+
+const fakeGitHubAppPrivateKey = `-----BEGIN RSA PRIVATE KEY-----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+-----END RSA PRIVATE KEY-----`
+
+func TestDiscoverGitHubAppInstallationID(t *testing.T) {
+	t.Run("returns cached installation ID", func(t *testing.T) {
+		// Setup: prepopulate cache
+		org := "test-org"
+		appId := int64(12345)
+		domain := "github.com"
+		expectedId := int64(98765)
+
+		// Clean up at both start and end to ensure test isolation
+		cacheKey := fmt.Sprintf("%s:%s:%d", strings.ToLower(org), domain, appId)
+
+		githubInstallationIdCache.Set(cacheKey, expectedId, gocache.NoExpiration)
+
+		// Ensure cleanup even if test fails
+		t.Cleanup(func() {
+			githubInstallationIdCache.Delete(cacheKey)
+		})
+
+		// Execute
+		ctx := context.Background()
+		actualId, err := DiscoverGitHubAppInstallationID(ctx, appId, "fake-key", "", org)
+
+		// Assert
+		require.NoError(t, err)
+		assert.Equal(t, expectedId, actualId)
+	})
+
+	t.Run("discovers installation ID from GitHub API", func(t *testing.T) {
+		// Setup: mock GitHub API server
+		server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			// GitHub Enterprise expects paths like /api/v3/app/installations
+			// go-github's WithEnterpriseURLs adds this prefix automatically
+			if strings.HasSuffix(r.URL.Path, "/app/installations") {
+				w.WriteHeader(http.StatusOK)
+				//nolint:errcheck
+				json.NewEncoder(w).Encode([]map[string]any{
+					{"id": 98765, "account": map[string]any{"login": "test-org"}},
+				})
+				return
+			}
+			// Return 404 for any other path
+			w.WriteHeader(http.StatusNotFound)
+		}))
+		defer server.Close()
+
+		// Clean up cache entry for this test on completion
+		t.Cleanup(func() {
+			// Extract domain from server URL for proper cache key
+			domain, _ := domainFromBaseURL(server.URL)
+			cacheKey := fmt.Sprintf("%s:%s:%d", strings.ToLower("test-org"), domain, 12345)
+			githubInstallationIdCache.Delete(cacheKey)
+		})
+
+		// Execute & Assert
+		ctx := context.Background()
+		// Pass the mock server URL as the enterpriseBaseURL so the GitHub client uses it
+		// Note: The mock server will have a different domain (e.g., 127.0.0.1) than the first test (github.com),
+		// so there's no cache collision between the two subtests.
+		actualId, err := DiscoverGitHubAppInstallationID(ctx, 12345, fakeGitHubAppPrivateKey, server.URL, "test-org")
+		require.NoError(t, err)
+		assert.Equal(t, int64(98765), actualId)
+	})
+}
+
+func TestExtractOrgFromRepoURL(t *testing.T) {
+	tests := []struct {
+		name        string
+		repoURL     string
+		expected    string
+		expectError bool
+	}{
+		{"HTTPS URL", "https://github.com/argoproj/argo-cd", "argoproj", false},
+		{"HTTPS URL with .git", "https://github.com/argoproj/argo-cd.git", "argoproj", false},
+		{"HTTPS URL with port", "https://github.com:443/argoproj/argo-cd.git", "argoproj", false},
+		{"SSH URL", "git@github.com:argoproj/argo-cd.git", "argoproj", false},
+		{"SSH URL without .git", "git@github.com:argoproj/argo-cd", "argoproj", false},
+		{"SSH URL with ssh:// prefix", "ssh://git@github.com:argoproj/argo-cd.git", "argoproj", false},
+		{"SSH URL with port", "ssh://git@github.com:22/argoproj/argo-cd.git", "argoproj", false},
+		{"GitHub Enterprise HTTPS", "https://github.example.com/myorg/myrepo.git", "myorg", false},
+		{"GitHub Enterprise SSH", "git@github.example.com:myorg/myrepo.git", "myorg", false},
+		{"Case insensitive", "https://github.com/ArgoPROJ/argo-cd", "argoproj", false}, // Test case sensitivity
+		{"Invalid URL", "not-a-url", "", true},
+		{"Empty string", "", "", true},
+		{"URL without org/repo", "https://github.com", "", true},
+		{"URL with only org", "https://github.com/argoproj", "", true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			actual, err := ExtractOrgFromRepoURL(tt.repoURL)
+			if tt.expectError {
+				require.Error(t, err)
+				assert.Empty(t, actual)
+			} else {
+				require.NoError(t, err)
+				assert.Equal(t, tt.expected, actual)
+			}
+		})
+	}
+}
diff --git a/util/git/git_test.go b/util/git/git_test.go
index 555695d44a..6a844b326f 100644
--- a/util/git/git_test.go
+++ b/util/git/git_test.go
@@ -10,12 +10,21 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
+	"github.com/argoproj/argo-cd/v3/util/proxy"
+
 	"github.com/argoproj/argo-cd/v3/common"
 	"github.com/argoproj/argo-cd/v3/test/fixture/log"
 	"github.com/argoproj/argo-cd/v3/test/fixture/path"
 	"github.com/argoproj/argo-cd/v3/test/fixture/test"
 )
 
+func TestMain(m *testing.M) {
+	// Ensure tests use non-cached proxy callback
+	proxy.UseTestingProxyCallback()
+
+	os.Exit(m.Run())
+}
+
 func TestIsCommitSHA(t *testing.T) {
 	assert.True(t, IsCommitSHA("9d921f65f3c5373b682e2eb4b37afba6592e8f8b"))
 	assert.True(t, IsCommitSHA("9D921F65F3C5373B682E2EB4B37AFBA6592E8F8B"))
diff --git a/util/proxy/proxy.go b/util/proxy/proxy.go
index c4349e8ad4..cd7b7eba18 100644
--- a/util/proxy/proxy.go
+++ b/util/proxy/proxy.go
@@ -9,6 +9,19 @@ import (
 	"golang.org/x/net/http/httpproxy"
 )
 
+// DefaultProxyCallback is the default proxy callback function that reads from environment variables. http.ProxyFromEnvironment
+// is cached on first call, so we can't use it for tests. When writing a test that uses t.Setenv for some proxy env var,
+// call UseTestingProxyCallback.
+var DefaultProxyCallback = http.ProxyFromEnvironment
+
+// UseTestingProxyCallback sets the DefaultProxyCallback to use httpproxy.FromEnvironment. This is useful for tests that
+// use t.Setenv to set proxy env variables.
+func UseTestingProxyCallback() {
+	DefaultProxyCallback = func(r *http.Request) (*url.URL, error) {
+		return httpproxy.FromEnvironment().ProxyFunc()(r.URL)
+	}
+}
+
 // UpsertEnv removes the existing proxy env variables and adds the custom proxy variables
 func UpsertEnv(cmd *exec.Cmd, proxy string, noProxy string) []string {
 	envs := []string{}
@@ -42,7 +55,7 @@ func GetCallback(proxy string, noProxy string) func(*http.Request) (*url.URL, er
 		}
 	}
 	// read proxy from env variable if custom proxy is missing
-	return http.ProxyFromEnvironment
+	return DefaultProxyCallback
 }
 
 func httpProxy(url string) string {
diff --git a/util/proxy/proxy_test.go b/util/proxy/proxy_test.go
index 39a50fdf0c..c1617d6ed8 100644
--- a/util/proxy/proxy_test.go
+++ b/util/proxy/proxy_test.go
@@ -4,6 +4,7 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"net/url"
+	"os"
 	"os/exec"
 	"testing"
 
@@ -11,6 +12,13 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+func TestMain(m *testing.M) {
+	// Ensure tests use non-cached proxy callback
+	UseTestingProxyCallback()
+
+	os.Exit(m.Run())
+}
+
 func TestAddProxyEnvIfAbsent(t *testing.T) {
 	t.Run("Existing proxy env variables", func(t *testing.T) {
 		proxy := "https://proxy:5000"