OpenClaw's Slack channel picked up a delivery reliability fix in PR #103442, which landed late on July 10. The issue is narrow but operationally painful: Slack's external file-upload byte endpoint could accept an upload and then hang indefinitely.
For an always-on agent, an indefinite media upload is more than a slow request. It can retain media in memory, block durable delivery, and leave the queue stuck behind an operation that may never finish.
The Timeout Is Deliberately Limited
The new behavior gives the raw byte POST a 120-second budget. If that upload stage stalls, OpenClaw can fail it before dispatch and classify the result as safe to replay.
The fix does not apply the same timeout to Slack's completion call. That is intentional. files.completeUploadExternal is a commit-capable, one-shot operation, so timing it out would create an ambiguous state: the upload might have completed remotely even if OpenClaw did not receive the response.
PR #103442 keeps that distinction clear:
- The raw upload step is bounded.
- Completion remains untimed and non-retryable.
- Ordinary Slack API traffic still uses the Bolt listener client.
- The completion path uses a cached completion-only web client.
That separation is the key detail. OpenClaw is not just adding a timer; it is preserving the line between work that can be replayed and work that may already have committed externally.
Host Boundaries Got Tighter Too
The PR also hardens which upload endpoints are accepted. Upload capabilities are accepted only from exact canonical Slack or GovSlack upload hosts, or from the exact origin of a configured custom Slack API root.
That matters because file upload flows often involve pre-signed or capability-style URLs. OpenClaw needs to follow Slack's upload path without accidentally broadening the agent's network trust boundary.
The existing RFC2544 benchmark-range allowance remains in place, but the Slack external upload route now has a clearer host policy for real delivery traffic.
Durable Delivery Can Recover
The user impact is straightforward: a stalled Slack file upload can now fail after 120 seconds and be replayed safely instead of holding the queue indefinitely.
The PR's evidence included a controlled upload proof where a normal randomized PNG upload completed in milliseconds, while a staged raw byte upload timed out after roughly 120 seconds with a typed not-dispatched result. The test suite also covered Slack, outbound queue, and plugin SDK paths.
That testing focus is encouraging because delivery bugs are rarely isolated to one function. A file upload touches queue classification, retry behavior, transport clients, and user-visible message state.
Why It Matters
Slack remains one of OpenClaw's most important high-volume channels. Agents send logs, screenshots, generated files, summaries, and operator handoff artifacts through it. When media delivery stalls, users need OpenClaw to recover without double-sending completed uploads or silently losing work.
This fix lands in the right place: before completion, where replay can still be proven safe. It is a good example of OpenClaw's current reliability direction, where the system is becoming more careful about external side effects instead of treating every network failure the same way.