make linkedin version API configurable

4 files changed, 43 insertions, 15 deletions

diff --git a/README.md b/README.md
index ef9051a..82dbe16 100644
--- a/README.md
+++ b/README.md
@@ -62,7 +62,8 @@ Example Configuration File (`~/.config/gos/gos.json`):
   "MastodonAccessToken": "your-mastodon-access-token",
   "LinkedInClientID": "your-linkedin-client-id",
   "LinkedInSecret": "your-linkedin-client-secret",
-  "LinkedInRedirectURL": "http://localhost:8080/callback"
+  "LinkedInRedirectURL": "http://localhost:8080/callback",
+  "LinkedInVersion": ""  
 }
 ```
 
@@ -86,11 +87,20 @@ Example with pause period configured:
 * `LinkedInClientID`: The client ID for your LinkedIn app, which is needed for OAuth2 authentication.
 * `LinkedInSecret`: The client secret for your LinkedIn app.
 * `LinkedInRedirectURL`: The redirect URL configured for handling OAuth2 responses.
+* `LinkedInVersion`: (Optional) LinkedIn API version header value (e.g., `202502`). Set this if you receive 426 Upgrade Required with `NONEXISTENT_VERSION`. Leave empty to omit the header and use LinkedIn's default.
 * `LinkedInAccessToken`: Gos will automatically update this after successful OAuth2 authentication with LinkedIn.
 * `LinkedInPersonID`: Gos will automatically update this after successful OAuth2 authentication with LinkedIn.
 * `PauseStart`: (Optional) Start date for pausing all posts in YYYY-MM-DD format.
 * `PauseEnd`: (Optional) End date for pausing all posts in YYYY-MM-DD format.
 
+### LinkedIn API versioning
+
+LinkedIn requires an active API version via the `LinkedIn-Version` header for some endpoints. If you see an error like:
+
+`Status: 426 Upgrade Required {"code":"NONEXISTENT_VERSION","message":"Requested version <date> is not active"}`
+
+set an active version string (e.g., `202502`) in the `LinkedInVersion` field of your config. You can also clear the field to omit the header and fall back to LinkedIn's default version.
+
 ### Automatically managed fields
 
 Once you finish the OAuth2 setup (after the initial run of `gos`), some fields—like `LinkedInAccessToken` and `LinkedInPersonID` will get filled in automatically. To check if everything's working without actually posting anything, you can run the app in dry run mode with the `--dry` option. After OAuth2 is successful, the file will be updated with `LinkedInClientID` and `LinkedInAccessToken`. If the access token expires, it will go through the OAuth2 process again.
diff --git a/examples/gos.json b/examples/gos.json
index 2b033c6..d8e9082 100644
--- a/examples/gos.json
+++ b/examples/gos.json
@@ -4,6 +4,7 @@
   "LinkedInClientID": "CENSORED",
   "LinkedInSecret": "CENSORED",
   "LinkedInRedirectURL": "http://localhost:8080/callback",
+  "LinkedInVersion": "",
   "LinkedInAccessToken": "CENSORED",
   "LinkedInPersonID": "CENSORED"
 }
diff --git a/internal/config/config.go b/internal/config/config.go
index 1504b95..8b101be 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -19,6 +19,10 @@ type Config struct {
 	LinkedInClientID    string
 	LinkedInSecret      string
 	LinkedInRedirectURL string
+	// Optional LinkedIn API version header value (e.g., "202502").
+	// When set, requests include `LinkedIn-Version: <value>`.
+	// Leave empty to omit the header and use LinkedIn's default.
+	LinkedInVersion string `json:"LinkedInVersion,omitempty"`
 	// Will be updated by gos automatically, after successful oauth2
 	LinkedInAccessToken string `json:"LinkedInAccessToken,omitempty"`
 	// Will be updated by gos automatically, after successful oauth2
diff --git a/internal/platforms/linkedin/linkedin.go b/internal/platforms/linkedin/linkedin.go
index 4c63f9a..11291fb 100644
--- a/internal/platforms/linkedin/linkedin.go
+++ b/internal/platforms/linkedin/linkedin.go
@@ -22,6 +22,16 @@ var errUnauthorized = errors.New("unauthorized access, refresh or create token?"
 
 const linkedInTimeout = 10 * time.Second
 
+// addCommonHeaders applies required headers and optional LinkedIn versioning.
+func addCommonHeaders(req *http.Request, accessToken, liVersion string) {
+	req.Header.Set("Authorization", "Bearer "+accessToken)
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("X-RestLi-Protocol-Version", "2.0.0")
+	if liVersion != "" {
+		req.Header.Set("LinkedIn-Version", liVersion)
+	}
+}
+
 func Post(ctx context.Context, args config.Args, sizeLimit int, en entry.Entry) error {
 	err := post(ctx, args, sizeLimit, en)
 	if errors.Is(err, errUnauthorized) {
@@ -68,11 +78,11 @@ func post(ctx context.Context, args config.Args, sizeLimit int, en entry.Entry)
 
 	newCtx, cancel = context.WithTimeout(ctx, linkedInTimeout)
 	defer cancel()
-	return postMessageToLinkedInAPI(newCtx, personID, accessToken, content, prev)
+	return postMessageToLinkedInAPI(newCtx, personID, accessToken, content, prev, args.Config.LinkedInVersion)
 }
 
 // https://learn.microsoft.com/en-us/linkedin/marketing/community-management/shares/posts-api
-func postMessageToLinkedInAPI(ctx context.Context, personID, accessToken, content string, prev preview) error {
+func postMessageToLinkedInAPI(ctx context.Context, personID, accessToken, content string, prev preview, liVersion string) error {
 	const linkedInPostsURL = "https://api.linkedin.com/rest/posts"
 
 	personURN := fmt.Sprintf("urn:li:person:%s", personID)
@@ -91,7 +101,7 @@ func postMessageToLinkedInAPI(ctx context.Context, personID, accessToken, conten
 
 	article := map[string]interface{}{}
 	if thumbnailPath, ok := prev.Thumbnail(); ok {
-		thumbnailURN, err := postImageToLinkedInAPI(ctx, personURN, accessToken, thumbnailPath)
+		thumbnailURN, err := postImageToLinkedInAPI(ctx, personURN, accessToken, thumbnailPath, liVersion)
 		if err != nil {
 			return err
 		}
@@ -112,10 +122,11 @@ func postMessageToLinkedInAPI(ctx context.Context, personID, accessToken, conten
 		return fmt.Errorf("Error creating request: %w", err)
 	}
 
-	req.Header.Add("Authorization", "Bearer "+accessToken)
-	req.Header.Set("Content-Type", "application/json")
-	req.Header.Add("X-RestLi-Protocol-Version", "2.0.0")
-	req.Header.Add("LinkedIn-Version", "202409")
+	// Use configured LinkedIn version if available
+	addCommonHeaders(req, accessToken, liVersion)
+	if liVersion != "" {
+		colour.Infoln("Using LinkedIn-Version", liVersion)
+	}
 
 	client := &http.Client{}
 	resp, err := client.Do(req)
@@ -133,21 +144,25 @@ func postMessageToLinkedInAPI(ctx context.Context, personID, accessToken, conten
 			resp.Status, string(body))
 		if resp.StatusCode == http.StatusUnauthorized {
 			err = errors.Join(err, errUnauthorized)
+		} else if resp.StatusCode == http.StatusUpgradeRequired {
+			// 426 often indicates a non-active LinkedIn-Version header.
+			// Provide a clear hint to configure a valid version.
+			err = fmt.Errorf("%w; LinkedIn API version likely inactive. Set an active 'LinkedInVersion' in config (e.g. 202502) or remove to use default. Response: %s", err, string(body))
 		}
 	}
 	return err
 }
 
 // https://learn.microsoft.com/en-us/linkedin/marketing/community-management/shares/images-api
-func postImageToLinkedInAPI(ctx context.Context, personURN, accessToken, imagePath string) (string, error) {
-	uploadURL, imageURN, err := initializeImageUpload(ctx, personURN, accessToken)
+func postImageToLinkedInAPI(ctx context.Context, personURN, accessToken, imagePath string, liVersion string) (string, error) {
+	uploadURL, imageURN, err := initializeImageUpload(ctx, personURN, accessToken, liVersion)
 	if err != nil {
 		return imageURN, err
 	}
 	return imageURN, performImageUpload(ctx, imagePath, uploadURL, accessToken)
 }
 
-func initializeImageUpload(ctx context.Context, personURN, accessToken string) (string, string, error) {
+func initializeImageUpload(ctx context.Context, personURN, accessToken string, liVersion string) (string, string, error) {
 	const linkedInAPIURL = "https://api.linkedin.com/rest/images?action=initializeUpload"
 
 	type InitializeUploadRequest struct {
@@ -156,7 +171,6 @@ func initializeImageUpload(ctx context.Context, personURN, accessToken string) (
 	requestBody, err := json.Marshal(map[string]interface{}{
 		"initializeUploadRequest": InitializeUploadRequest{Owner: personURN},
 	})
-
 	if err != nil {
 		return "", "", fmt.Errorf("error creating request body: %w", err)
 	}
@@ -167,9 +181,8 @@ func initializeImageUpload(ctx context.Context, personURN, accessToken string) (
 		return "", "", fmt.Errorf("error creating request: %w", err)
 	}
 
-	req.Header.Set("Authorization", "Bearer "+accessToken)
-	req.Header.Set("Content-Type", "application/json")
-	req.Header.Add("LinkedIn-Version", "202409")
+	// Version header is optional and configurable
+	addCommonHeaders(req, accessToken, liVersion)
 
 	client := &http.Client{}
 	resp, err := client.Do(req)