feat: add ssh port forwarding for remote previews by jschwxrz · Pull Request #2544 · generalaction/emdash

jschwxrz · 2026-06-16T19:49:26Z

add automatic ssh port forwarding when terminal output detects local preview urls
replace host rewriting with local loopback urls backed by ssh tunnels
add preview server state for direct and forwarded previews with status and lifecycle cleanup
surface preview server controls for open, copy, stop, restart and manual forwarding
remove legacy host preview events and dev server store/pills

arnestrickmann · 2026-06-17T02:11:21Z

Very nice, works great.

One thing I noticed:

When I click a URL for a started dev server in the terminal drawer and open it in the Emdash browser, the URL includes a trailing ) at the end. Because of that, the dev server doesn’t open correctly until I manually remove the ) from the URL.

greptile-apps · 2026-06-17T18:18:16Z

Greptile Summary

This PR replaces the legacy host-rewriting dev-server detection approach with a full SSH port-forwarding pipeline. Terminal output is now scanned for local URLs, which are registered as either direct (localhost / 127.0.0.1) or forwarded (SSH tunnel via node:net → SSH channel) preview servers, surfaced to the renderer through a new PreviewServerStore and per-server pill UI.

Introduces PortForwardService / PortForwardTunnel for managing local TCP listeners that proxy through SSH channels, with preferred-port / port-0 fallback and onConnectionError callbacks.
Adds PreviewServerService to coordinate server lifecycle (auto-detect from terminal output, manual forward, restart, stop) with concurrent-stop guards and SSH connection event handling.
Replaces the old dev-server-watcher and dev-server-store with the new wireTerminalUrlDetector + PreviewServerStore, and surfaces open/copy/stop/restart controls in a dropdown pill component.

Confidence Score: 4/5

Safe to merge for most users; two edge-case resource leaks in the port-forward layer are worth tracking but do not affect normal usage.

The concurrent-restart path in PortForwardService.open can produce an orphaned TCP listener, and the 250ms PTY-exit guard can transiently drop a forwarded preview server after SSH reconnect without guaranteed re-detection — both only matter in narrow race windows and are self-healing through normal user actions. Core correctness of the auto-detect, manual forward, and teardown paths is solid and well-covered by the new test suite.

port-forward-service.ts (concurrent open guard) and preview-server-service.ts (PTY-exit timeout interaction with reconnect/rehydrate).

Important Files Changed

Filename	Overview
apps/emdash-desktop/src/main/core/port-forwards/port-forward-service.ts	New service managing SSH port-forward tunnels; clean abstraction, but `open` has a same-ID concurrency window that can orphan a TCP server if called twice before either resolves.
apps/emdash-desktop/src/main/core/port-forwards/port-forward-tunnel.ts	Implements TCP-to-SSH-channel forwarding using node:net; correctly handles EADDRINUSE fallback to port 0 and cleans up sockets on close.
apps/emdash-desktop/src/main/core/preview-servers/preview-server-service.ts	Core orchestration of preview server lifecycle; `forwardManual` correctly adds the server before async ops to avoid teardown leaks. The SSH PTY-exit→reconnect path has a window where the server is transiently removed and may not re-appear if the remote dev server doesn't re-emit its URL.
apps/emdash-desktop/src/main/core/preview-servers/terminal-url-detector.ts	Parses and deduplicates local URLs from PTY output; correctly strips ANSI, normalizes hosts, and probes local ports with a consecutive-failure threshold.
apps/emdash-desktop/src/renderer/features/tasks/stores/preview-server-store.ts	Renderer-side MobX store with event-driven sync and optimistic local updates for stop/restart/forwardManual; workspace filtering is correct.
apps/emdash-desktop/src/renderer/features/tasks/components/preview-servers/preview-server-pill.tsx	Dropdown pill component for preview servers; correctly gates Open/Copy actions on `canOpen`/`hasUrl` and displays forwarding metadata.
apps/emdash-desktop/src/renderer/features/tasks/components/preview-servers/manual-forward-dialog.tsx	New dialog for manually forwarding a port; validates port range, handles async submission, and surfaces error messages.
apps/emdash-desktop/src/shared/core/preview-servers/types.ts	Shared type definitions for direct and forwarded preview servers; `previewServerUrl` correctly returns null when `localPort` is undefined.
apps/emdash-desktop/src/main/core/terminals/impl/ssh-terminal-provider.ts	Wires `wireTerminalUrlDetector` (replacing old `dev-server-watcher`) with `probeLocalPorts: false` and forwards detected URLs via the singleton `previewServerService`.
apps/emdash-desktop/src/main/core/terminals/impl/local-terminal-provider.ts	Wires URL detector for local terminals with `probeLocalPorts: true`; registers direct preview servers with host/port from detected output.
apps/emdash-desktop/src/shared/terminal-url.ts	Extracted from `external-url.ts` so the same normalization logic is usable in shared/main context; behavior is identical to the removed code.

Sequence Diagram

%%{init: {'theme': 'neutral'}}%%
sequenceDiagram
    participant PTY as PTY (SSH/Local)
    participant URLDet as TerminalUrlDetector
    participant PSS as PreviewServerService
    participant PFS as PortForwardService
    participant Tunnel as PortForwardTunnel (node:net)
    participant SSH as SSH Channel
    participant Store as PreviewServerStore (renderer)

    PTY->>URLDet: onData(chunk)
    URLDet->>URLDet: "match URL pattern, parse & deduplicate"
    URLDet->>PSS: onDetected(server)
    PSS->>PSS: registerSshTarget / registerLocalTarget
    PSS->>Store: emit upsert (status: starting)
    PSS->>PFS: open(tunnelId, remotePort)
    PFS->>Tunnel: bind TCP server on localhost:preferredPort
    Tunnel->>SSH: forwardOut(remotePort)
    Tunnel-->>PFS: localPort
    PFS-->>PSS: PortForwardRecord
    PSS->>Store: emit upsert (status: ready, localPort)

    Note over PTY,Store: Manual forward path
    Store->>PSS: forwardManual(connectionId, remotePort)
    PSS->>Store: emit upsert (status: starting)
    PSS->>PFS: open(tunnelId, remotePort)
    PFS-->>PSS: PortForwardRecord
    PSS->>Store: emit upsert (status: ready, localPort)

    Note over PTY,Store: SSH connection events
    SSH-->>PSS: handleSshConnectionEvent(reconnected/failed)
    PSS->>Store: emit upsert (status: ready/reconnecting/failed)

%%{init: {'theme': 'base', 'themeVariables': {"darkMode": true, "background": "#0d1117", "primaryColor": "#21262d", "primaryTextColor": "#e6edf3", "primaryBorderColor": "#8b949e", "lineColor": "#8b949e", "textColor": "#e6edf3", "edgeLabelBackground": "#161b22", "actorBkg": "#21262d", "actorBorder": "#8b949e", "actorTextColor": "#e6edf3", "actorLineColor": "#8b949e", "signalColor": "#8b949e", "signalTextColor": "#e6edf3", "noteBkgColor": "#373320", "noteBorderColor": "#d4a72c", "noteTextColor": "#f0e6c0", "labelBoxBkgColor": "#21262d", "labelBoxBorderColor": "#8b949e", "labelTextColor": "#e6edf3", "loopTextColor": "#e6edf3", "activationBkgColor": "#30363d", "activationBorderColor": "#8b949e"}}}%%
sequenceDiagram
    participant PTY as PTY (SSH/Local)
    participant URLDet as TerminalUrlDetector
    participant PSS as PreviewServerService
    participant PFS as PortForwardService
    participant Tunnel as PortForwardTunnel (node:net)
    participant SSH as SSH Channel
    participant Store as PreviewServerStore (renderer)

    PTY->>URLDet: onData(chunk)
    URLDet->>URLDet: "match URL pattern, parse & deduplicate"
    URLDet->>PSS: onDetected(server)
    PSS->>PSS: registerSshTarget / registerLocalTarget
    PSS->>Store: emit upsert (status: starting)
    PSS->>PFS: open(tunnelId, remotePort)
    PFS->>Tunnel: bind TCP server on localhost:preferredPort
    Tunnel->>SSH: forwardOut(remotePort)
    Tunnel-->>PFS: localPort
    PFS-->>PSS: PortForwardRecord
    PSS->>Store: emit upsert (status: ready, localPort)

    Note over PTY,Store: Manual forward path
    Store->>PSS: forwardManual(connectionId, remotePort)
    PSS->>Store: emit upsert (status: starting)
    PSS->>PFS: open(tunnelId, remotePort)
    PFS-->>PSS: PortForwardRecord
    PSS->>Store: emit upsert (status: ready, localPort)

    Note over PTY,Store: SSH connection events
    SSH-->>PSS: handleSshConnectionEvent(reconnected/failed)
    PSS->>Store: emit upsert (status: ready/reconnecting/failed)

_{Reviews (2): Last reviewed commit: "fix(preview): avoid focusing disabled pr..." | Re-trigger Greptile}

jschwxrz · 2026-06-17T19:26:36Z

@greptileai

…rwarding feat: add ssh port forwarding for remote previews

jschwxrz added 5 commits June 16, 2026 12:38

feat(preview): add SSH port forwarding backend

8de1f67

feat(preview): surface preview server controls

e26957a

refactor(preview): remove legacy host preview events

c56266b

chore: cleanup unused file

4176005

refactor(preview): require ssh proxy resolver

ee4ec77

jschwxrz mentioned this pull request Jun 16, 2026

[feat]: Add automatic port forwarding for SSH-connected projects #2458

Closed

jschwxrz added 3 commits June 16, 2026 13:42

fix: surface failed ssh preview tunnels

9ea331c

fix: handle stale ssh preview forwards

f56a5a8

Merge remote-tracking branch 'origin/main' into feat-port-forwarding

8267325

fix(preview): trim trailing terminal url punctuation

f9b5135

jschwxrz marked this pull request as ready for review June 17, 2026 18:08

greptile-apps Bot reviewed Jun 17, 2026

View reviewed changes

Comment thread ...mdash-desktop/src/renderer/features/tasks/components/preview-servers/preview-server-pill.tsx

jschwxrz added 2 commits June 17, 2026 11:42

fix(preview): handle manual forward teardown races

0461e9d

fix(preview): avoid focusing disabled preview action

62706c1

jschwxrz merged commit 4c1f31d into main Jun 17, 2026
1 check passed

jschwxrz mentioned this pull request Jun 17, 2026

[feat]: Dev server preview URL should use SSH connection host for remote projects #1979

Closed

fiorelorenzo mentioned this pull request Jun 19, 2026

SSH port forward only targets 127.0.0.1 — misses dev servers bound to localhost/::1 #2589

Closed

luisKisters pushed a commit to luisKisters/emdash that referenced this pull request Jul 29, 2026

Merge pull request generalaction#2544 from generalaction/feat-port-fo…

5bc54f5

…rwarding feat: add ssh port forwarding for remote previews

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feat: add ssh port forwarding for remote previews#2544
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jschwxrz commented Jun 16, 2026

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greptile-apps Bot commented Jun 17, 2026 •

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jschwxrz commented Jun 16, 2026

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Greptile Summary

Confidence Score: 4/5

Important Files Changed

Sequence Diagram

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jschwxrz commented Jun 17, 2026

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