CLI crashes in Spectre.Console.LiveRenderable over Remote SSH without a TTY

[ivnmood]

Bug description

aspire run crashes while rendering resource state when it is launched through VS Code Remote SSH without a real TTY. The AppHost and dashboard start successfully, but the CLI exits while updating the live resource list.

Environment

• Aspire CLI: 13.4.6
• .NET SDK: 10.0.302
• OS: Linux (kernel 6.8)
• Launch context: VS Code Remote SSH
• SSH_CONNECTION is set
• VSCODE_IPC_HOOK_CLI is set
• TERM=dumb
• stdout/stderr are not TTYs and the terminal height is reported as zero

Reproduction

Run an AppHost with a larger resource graph from a Remote SSH/non-TTY session:

pnpm start
# equivalent to:
aspire run --project <AppHost-project>.csproj

The AppHost builds, the dashboard begins listening, and resource state processing starts. Then the CLI exits with code 2:

System.ArgumentException: Offset and length were out of bounds for the array or count is greater than the number of elements from index to the end of the source collection.
   at System.Collections.Generic.List`1.RemoveRange(Int32, Int32)
   at Spectre.Console.LiveRenderable.<Render>d__25.MoveNext()
   at Spectre.Console.Rendering.RenderableExtensions.GetSegments(...)
   at Spectre.Console.LegacyConsoleBackend.Write(IRenderable)
   at Spectre.Console.LiveDisplayContext.Refresh()
   at Spectre.Console.LiveDisplayContext.UpdateTarget(IRenderable)
   at Aspire.Cli.Commands.RunCommand.ProcessResourceState(...)

Expected behavior

The CLI should avoid live rendering when stdout is not a usable TTY, or otherwise render resource state without throwing. The AppHost should remain running after the dashboard becomes available.

Workarounds verified

• Running the same command in a real PTY works.
• env -u VSCODE_IPC_HOOK_CLI pnpm start works as a one-command workaround.
• The direct .NET AppHost fallback works.
• Setting CI=1 or only setting COLUMNS/LINES does not fix it because those do not create a real TTY.

This appears related to non-interactive Spectre rendering issues discussed in #17410, #15203, #13875, #18010, and #12134, but I could not find an exact duplicate for this exception and Remote SSH environment.

[joperezr]

🤖 Aspire triage pass — 2026-08-12 15:30 UTC

Area: area-cli (stack trace is Aspire.Cli.Commands.RunCommand; issue currently also carries area-dashboard)
Kind: bug
Repro: yes-minimal — see the "Reproduction" section (lines 14–33 of the issue body)
Affected version(s): 13.4.6 (latest 13.4.x line; 13.5 wrapping up)
Severity: S3 — CLI crash in non-TTY Remote SSH, but multiple verified workarounds exist (real PTY, env -u VSCODE_IPC_HOOK_CLI, direct .NET AppHost)

Urgency: ⚪ backlog — no milestone
Reason: S3 bug with several verified workarounds and no evidence of regression from a prior 13.x; default to Backlog while 13.5 stabilizes

Suggested owner(s): James Newton-King (@JamesNK) (score 11), backup Mitch Denny (@mitchdenny) (score 6)
Evidence:

• JamesNK merged Preserve CLI status messages without interactive spinners #19272, Resolve dotnet paths in doctor checks #19232, Suppress CLI progress when console logging is enabled #19214, Show status while preparing dashboard bundle #18985 in area-cli (last 30d; 54 area-cli PRs in last 90d)
• mitchdenny merged Gate polyglot integration filtering behind an off-by-default feature flag #19222 in area-cli (last 30d; 6 area-cli PRs in last 90d)
• CODEOWNERS has no CLI-specific entry

Confidence: high
Needs human?: no

[adamint]

This is still reachable in the current non-Windows code path.

CliHostEnvironment rejects interactive output for explicit non-interactive mode and CI, but its console-handle validation only runs on Windows. A non-Windows process with redirected output can therefore still be classified as interactive. RunCommand then calls DisplayLiveAsync, which unconditionally creates a Spectre live display.

This was a focused source-path verification rather than a VS Code run, but the reported redirected-output path is still present.

[adamint]

Reproduced this on macOS against branch adamint-fix-remote-tty-crash at 1d7327cc (based on main 88c0bb39) with the repo-built CLI:

TERM=dumb LINES=0 COLUMNS=80 \
VSCODE_IPC_HOOK_CLI=<socket> \
SSH_CONNECTION='<client> <port> <server> <port>' \
artifacts/bin/Aspire.Cli/Debug/net10.0/aspire run \
  --project playground/DotnetProject/DotnetProject.AppHost/DotnetProject.AppHost.csproj \
  > <scratch>/stdout 2> <scratch>/stderr

The AppHost and dashboard started, then the CLI exited with code 2 when resource endpoints updated. I expected it to stay running and use plain output. The sanitized stack is:

System.ArgumentException: Offset and length were out of bounds...
   at System.Collections.Generic.List`1.RemoveRange(...)
   at Spectre.Console.LiveRenderable.Render(...)
   at Spectre.Console.LiveDisplayContext.UpdateTarget(...)
   at Aspire.Cli.Interaction.ConsoleInteractionService.DisplayLiveAsync(...)
   at Aspire.Cli.Commands.RunCommand.ProcessResourceState(...)

I have a focused fix in progress.