feat: 🎸 Implement message prefetching and link previews by highesttt · Pull Request #22 · beeper/line

highesttt · 2026-01-21T18:18:56Z

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Copilot

Pull request overview

This PR adds message prefetching and link preview functionality to the LINE messenger bridge. The implementation allows the bridge to fetch recent messages from all active chats on startup, and generates link previews for URLs found in incoming messages.

Changes:

Added data structures for message boxes, page info, and link previews
Implemented API methods to fetch message boxes and recent messages
Added message prefetching on connection to populate chat history
Integrated link preview generation for URLs in messages

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 11 comments.

Show a summary per file

File	Description
pkg/line/structs.go	Added new struct definitions for MessageBoxes, PageInfo, and related response wrappers
pkg/line/methods.go	Implemented GetMessageBoxes and GetRecentMessagesV2 RPC methods
pkg/line/client.go	Added GetPageInfo method to fetch link preview metadata from LINE API
pkg/connector/client.go	Implemented prefetchMessages goroutine, link preview extraction, and improved timestamp handling
README.md	Updated feature list to mark prefetch chats and link previews as completed

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Copilot · 2026-01-21T18:24:23Z

+							LinkPreview: event.LinkPreview{
+								Title:        info.Title,
+								Description:  info.Summary,
+								CanonicalURL: info.Domain,


The CanonicalURL field is being set to info.Domain instead of info.URL. According to the MSC2481 spec for link previews, CanonicalURL should contain the canonical URL of the page, not just the domain. This should likely be set to info.URL.

Suggested change

CanonicalURL: info.Domain,

CanonicalURL: info.URL,

Copilot · 2026-01-21T18:24:24Z

+	tsInt, _ := msg.CreatedTime.Int64()
+	ts := time.UnixMilli(tsInt)
+	if ts.IsZero() {
+		ts = time.Now()


The error from msg.CreatedTime.Int64() is silently ignored. If the conversion fails, tsInt will be 0, leading to an incorrect timestamp (Unix epoch). Consider checking the error and logging a warning or handling it appropriately.

Suggested change

tsInt, _ := msg.CreatedTime.Int64()

ts := time.UnixMilli(tsInt)

if ts.IsZero() {

ts = time.Now()

var ts time.Time

if tsInt, err := msg.CreatedTime.Int64(); err != nil {

lc.UserLogin.Bridge.Log.Warn().

Err(err).

Str("msg_id", msg.ID).

Msg("Failed to convert message CreatedTime to int64, using current time")

ts = time.Now()

} else {

ts = time.UnixMilli(tsInt)

if ts.IsZero() {

ts = time.Now()

}

Copilot · 2026-01-21T18:24:24Z

+			existing, err := lc.UserLogin.Bridge.DB.Message.GetPartByID(ctx, lc.UserLogin.ID, networkid.MessageID(msg.ID), "")
+			if err == nil && existing != nil {
+				continue


During prefetch, a database query is executed for every message (up to 5000 messages) to check if it already exists. This could create a performance bottleneck, especially with a large number of messages. Consider batching the existence checks or using a bloom filter to reduce database queries.

Copilot · 2026-01-21T18:24:24Z

+					if !strings.HasPrefix(match, "http") {
+						requestURL = "https://" + match
+					}
+					client := line.NewClient(lc.AccessToken)


A new LINE client is created for every message that contains a URL for fetching link preview information. This creates unnecessary overhead. Consider reusing the client instance that was already created in the queueIncomingMessage function scope (available as lc.AccessToken via line.NewClient).

Suggested change

client := line.NewClient(lc.AccessToken)

Copilot · 2026-01-21T18:24:24Z

+			if strings.Contains(unwrappedText, ".") {
+				urlRegex := regexp.MustCompile(`(https?://)?([a-zA-Z0-9.-]+\.[a-zA-Z]{2,})(/[^\s]*)?`)
+				if match := urlRegex.FindString(unwrappedText); match != "" {
+					match = strings.TrimRight(match, ".,;:!?")
+					requestURL := match
+					if !strings.HasPrefix(match, "http") {
+						requestURL = "https://" + match
+					}
+					client := line.NewClient(lc.AccessToken)
+					if info, err := client.GetPageInfo(requestURL); err == nil {
+						preview := &event.BeeperLinkPreview{
+							MatchedURL: match,
+							LinkPreview: event.LinkPreview{
+								Title:        info.Title,
+								Description:  info.Summary,
+								CanonicalURL: info.Domain,
+							},
+						}
+						if info.Image != "" && info.Obs.CDN != "" {
+							preview.ImageURL = id.ContentURIString(info.Obs.CDN + info.Image)
+						}
+						content.BeeperLinkPreviews = []*event.BeeperLinkPreview{preview}
+					}


The URL check using strings.Contains(unwrappedText, ".") is too broad and will trigger regex matching for any text containing a period, including sentences, decimal numbers, or file extensions. Consider a more specific check or move this logic after a successful regex match to avoid unnecessary processing.

Suggested change

if strings.Contains(unwrappedText, ".") {

urlRegex := regexp.MustCompile(`(https?://)?([a-zA-Z0-9.-]+\.[a-zA-Z]{2,})(/[^\s]*)?`)

if match := urlRegex.FindString(unwrappedText); match != "" {

match = strings.TrimRight(match, ".,;:!?")

requestURL := match

if !strings.HasPrefix(match, "http") {

requestURL = "https://" + match

}

client := line.NewClient(lc.AccessToken)

if info, err := client.GetPageInfo(requestURL); err == nil {

preview := &event.BeeperLinkPreview{

MatchedURL: match,

LinkPreview: event.LinkPreview{

Title: info.Title,

Description: info.Summary,

CanonicalURL: info.Domain,

},

}

if info.Image != "" && info.Obs.CDN != "" {

preview.ImageURL = id.ContentURIString(info.Obs.CDN + info.Image)

}

content.BeeperLinkPreviews = []*event.BeeperLinkPreview{preview}

}

urlRegex := regexp.MustCompile(`(https?://)?([a-zA-Z0-9.-]+\.[a-zA-Z]{2,})(/[^\s]*)?`)

if match := urlRegex.FindString(unwrappedText); match != "" {

match = strings.TrimRight(match, ".,;:!?")

requestURL := match

if !strings.HasPrefix(match, "http") {

requestURL = "https://" + match

}

client := line.NewClient(lc.AccessToken)

if info, err := client.GetPageInfo(requestURL); err == nil {

preview := &event.BeeperLinkPreview{

MatchedURL: match,

LinkPreview: event.LinkPreview{

Title: info.Title,

Description: info.Summary,

CanonicalURL: info.Domain,

},

}

if info.Image != "" && info.Obs.CDN != "" {

preview.ImageURL = id.ContentURIString(info.Obs.CDN + info.Image)

}

content.BeeperLinkPreviews = []*event.BeeperLinkPreview{preview}

Copilot · 2026-01-21T18:24:25Z

+	ts := time.UnixMilli(tsInt)
+	if ts.IsZero() {
+		ts = time.Now()


The timestamp check ts.IsZero() will not work as expected for Unix timestamps. A Unix timestamp of 0 (January 1, 1970) is a valid timestamp and will not be zero according to time.Time.IsZero(). Consider checking if tsInt == 0 before creating the time object, or check if tsInt < 0 to catch invalid values.

Suggested change

ts := time.UnixMilli(tsInt)

if ts.IsZero() {

ts = time.Now()

var ts time.Time

if tsInt <= 0 {

ts = time.Now()

} else {

ts = time.UnixMilli(tsInt)

Copilot · 2026-01-21T18:24:25Z

+			}
+
+			if strings.Contains(unwrappedText, ".") {
+				urlRegex := regexp.MustCompile(`(https?://)?([a-zA-Z0-9.-]+\.[a-zA-Z]{2,})(/[^\s]*)?`)


The URL regex pattern (https?://)?([a-zA-Z0-9.-]+\.[a-zA-Z]{2,})(/[^\s]*)? does not account for URLs with authentication credentials, ports, or certain special characters in paths (like parentheses, which are common in URLs). This could miss valid URLs or incorrectly match URL-like text. Consider using a more comprehensive URL matching pattern or a URL parsing library.

Copilot · 2026-01-21T18:24:25Z

+	}
+
+	q := req.URL.Query()
+	q.Add("url", url)


The URL parameter is passed directly to the LINE API without validation or sanitization. Consider validating that the URL is properly formatted and not empty before making the API call to avoid unnecessary requests with invalid URLs.

Copilot · 2026-01-21T18:24:26Z

+			}
+
+			if strings.Contains(unwrappedText, ".") {
+				urlRegex := regexp.MustCompile(`(https?://)?([a-zA-Z0-9.-]+\.[a-zA-Z]{2,})(/[^\s]*)?`)


The regex pattern is compiled on every message conversion. This regex should be compiled once and stored as a package-level variable to avoid repeated compilation overhead, especially during message prefetching where many messages could be processed.

Copilot · 2026-01-21T18:24:26Z

+					requestURL := match
+					if !strings.HasPrefix(match, "http") {
+						requestURL = "https://" + match
+					}


The GetPageInfo API call is made synchronously during message processing. This could significantly slow down message handling, especially during the prefetch phase where 50 messages per chat are processed. If a URL takes a long time to respond or times out, it will block message processing. Consider adding a timeout to the HTTP client or making link preview fetching asynchronous.

Suggested change

}

}

// Ensure a bounded timeout for any HTTP requests made by GetPageInfo.

if http.DefaultClient != nil {

clientCopy := *http.DefaultClient

clientCopy.Timeout = 5 * time.Second

http.DefaultClient = &clientCopy

}

Only create 1 new client when queuing incoming messages Added replies as fully supported and read receipts as true

feat: 🎸 Implement message prefetching and link previews

1ddc5ee

highesttt requested a review from Copilot January 21, 2026 18:18

highesttt linked an issue Jan 21, 2026 that may be closed by this pull request

feat: ✨ Prefetch Messages #21

Closed

Copilot started reviewing on behalf of highesttt January 21, 2026 18:19 View session

Copilot AI reviewed Jan 21, 2026

View reviewed changes

feat: 🎸 Improve message timestamp handling

7e57ec7

Only create 1 new client when queuing incoming messages Added replies as fully supported and read receipts as true

highesttt merged commit 6547e26 into main Jan 21, 2026
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feat: 🎸 Implement message prefetching and link previews#22

feat: 🎸 Implement message prefetching and link previews#22
highesttt merged 2 commits into
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21-feat-prefetch-messages

highesttt commented Jan 21, 2026

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-	tsInt, _ := msg.CreatedTime.Int64()
-	ts := time.UnixMilli(tsInt)
-	if ts.IsZero() {
-		ts = time.Now()
+	var ts time.Time
+	if tsInt, err := msg.CreatedTime.Int64(); err != nil {
+		lc.UserLogin.Bridge.Log.Warn().
+			Err(err).
+			Str("msg_id", msg.ID).
+			Msg("Failed to convert message CreatedTime to int64, using current time")
+		ts = time.Now()
+	} else {
+		ts = time.UnixMilli(tsInt)
+		if ts.IsZero() {
+			ts = time.Now()
+		}

-					}
+					}
+					// Ensure a bounded timeout for any HTTP requests made by GetPageInfo.
+					if http.DefaultClient != nil {
+						clientCopy := *http.DefaultClient
+						clientCopy.Timeout = 5 * time.Second
+						http.DefaultClient = &clientCopy
+					}

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Pull request overview

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