dsh-image-governor: DeepSeek Harness Session Image Payload Governance Plugin

Introduction¶

When developing multi-turn conversations with DeepSeek Harness, image attachments in the conversation context often accumulate continuously: screenshots generated by tools, interfaces read by the Agent, files pasted in earlier turns, and so on. These images are re-uploaded in every step request. Measured data shows that a session carrying 13 attachments (about 14.7 MB in base64) at an upload rate of 0.07–0.10 MB/s consumes 100–140 seconds per step for this alone, easily triggering gateway timeouts (around 150 seconds).

The existing routing-level solution is to set a maxRequestImageBytes limit. But this is a byte-based “byte budget” strategy, which usually keeps only the latest images. This leads to an awkward result: the original reference images that are actually depended upon become hidden, while the most recently generated artifacts remain visible.

The dsh-image-governor plugin returns control to developers, allowing you to specify explicitly, for a single session, which images to keep and which to move out of the model’s view.

Plugin Positioning¶

Name: dsh-image-governor
Positioning: Session image payload governor.
Function: Audits the images currently carried by a session, allows manual filtering and removal of redundant images, and only changes the model’s view without deleting the actual attachments.
Maintainer: 2432450223
License: MIT

Core Features¶

Interactive Interface¶

Picker overlay: Provides a full-screen overlay in the bottom-right corner (shell.overlay), listing all sessions that carry images. The same panel is also registered next to the session title.
Operation method: When the panel opens, no images are selected by default. Checkboxes are the operation targets and support preset logic (keep newest, hide from model, select all, clear).
Undo mechanism: After each write change, the panel provides an undo entry.

Command-line Tool¶

View status: /images status. Displays historical image sizes, actual sent payloads, and images hidden by the limit rule.
Remove images: /images clear [keep <seq|name|id> …] [--newest N] [--yes].
- Supports specifying kept items by sequence number, file name, or ID.
- --newest N quickly keeps the N latest images.
- Without --yes, it only previews; without arguments, it clears.
Restore images: /images restore [--yes]. Puts previously removed images back into the view.

Installation and Enablement¶

This plugin is pure JavaScript with no build steps. The installation command is as follows:

dsh plugin --profile web add github:2432450223/dsh-image-governor

Typical Usage¶

Confirm the current image payload:
Enter the following in the session:

    /images status

Check how many images are present and the bandwidth they occupy.

Clean up unneeded images:
If certain images are unneeded, select them and run:

    /images clear

The system displays a preview. After confirming, add `--yes` to force execution:

    /images clear --yes

Restore images removed by mistake:
If you discover an accidental removal, immediately run:

    /images restore --yes

Technical Details and Limitations¶

Implementation principle: The plugin does not modify frozen outbound requests. It uses the surface-replacing protocol allowed by the session format to append position-replacement operations ({ op: 'replace', start, end }), replacing image blocks with text placeholders. The original image events remain in the append-only log, so restore works.
File operations: The plugin does not delete any attachments. The attachment service itself does not provide deletion operations, and this plugin does not write to the attachment service either.
Execution timing: Write operations are only executed when the session is idle. While an Agent is running a turn, write requests are rejected.
Dependencies: Zero dependencies, pure JavaScript. It reads services via ctx.get; missing services only degrade functionality without blocking startup.
Permission note: This plugin runs within the DSH process permission scope. Please check the source code and license (MIT) before installing.

Conclusion¶

dsh-image-governor provides a refined way to manage images in the conversation context, avoiding performance degradation and context loss caused by excessive attachments. For more details and source code, refer to the project homepage.