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Update architecture diagram to include the /dls filesystem mount #225
Description
Description
The architecture diagram should show the DLS shared filesystem (/dls) as a component, since it's now load-bearing for image serving:
- The agent ingests EPU output from the workstation filesystem (and records
/dls/...paths into the DB). - The backend API (image-serving endpoints) reads atlas/grid-square files back off
/dlsto serve them to the frontend. - In local dev this is a hostPath mount of
testdata/dls-filesystem(devtools PR feat: mount local DLS-filesystem mirror into dev backend for image serving #223); in stage/prod it's the real DLS NFS/PVC (devtools PR docs: DLS filesystem mount placeholder for prod/stage API #224).
Scope
- Add
/dlsfilesystem node + the agent-ingest and API-read edges to the architecture diagram indocs/decision-records/backend-agent-communication-system-design.md. - Keep the webui mirror in sync (
webui/src/docs/decision-records/backend-agent-communication-system-design.mdx).
Notes
Captured during the image-path-resolution work (2026-06-08). Lower priority than the functional changes; deferred deliberately.
Activity
vredchenko commentedon Sep 2, 2026
Closing as superseded by #187, which rescopes documentation from incremental correction to a
complete rewrite of structure and content. Updating a diagram that is going to be redrawn is
duplicated effort, and the second scope item here - keeping the webui mirror in sync - refers to
a rendering layer that has since been deprioritised (#219, #220).
The substance should carry into that rework, and has become more significant since this was
filed.
/dlsis not simply another component: image serving reads file paths directly from thedatabase with no resolution layer between them and the filesystem (see
DiamondLightSource/smartem-decisions#297), so the mount is a hard dependency rather than a
convenience. If it is absent, or the stored paths do not match what is on disk, image serving
fails outright. A diagram that omits it conceals the most fragile edge in the system.
Both referenced PRs are merged: #223 mounts a local DLS-filesystem mirror into the dev backend,
and #224 adds the production/staging placeholder.