fix: un-deprecate coder_agent dir

[aqandrew]

Summary

Un-deprecates coder_agent.dir by reverting #507.

#507 (DEVEX-227) added the Deprecated: field, the ~> Warning description block, and the WarnDirNotHome plan-time validator together, solely because a non-$HOME dir broke Coder Desktop file sync. That is fixed in coder/mutagen#10, now released and bundled into the macOS and Windows Desktop clients. @matifali, @code-asher, and @zenithwolf1000 confirmed in this PR that file sync was the only reason for the deprecation.

Tracked in DESK-2.

Changes

• provider/agent.go: remove Deprecated: and ValidateFunc from dir. The description now notes that SFTP and scp resolve relative and ~/-prefixed paths against dir, so file transfers should use absolute paths. The rest of the file matches its state before chore: warn when coder_agent dir breaks Desktop file sync #507.
• provider/helpers/validation.go, validation_test.go: delete WarnDirNotHome and TestWarnDirNotHome.
• docs/resources/agent.md: regenerated with make gen. dir is listed as a plain (String) again.

Why keep a note about scp

Modern OpenSSH scp strips ~/ on the client (prepare_remote_path()), so scp host:~/foo lands in dir. The server can't tell ~/foo from foo, and devcontainer workspaceFolder behaves the same way regardless of dir, so this is documented instead of warned about.

Testing

• go test ./provider/..., go build ./..., go vet ./provider/..., and gofmt pass.
• make gen diff is limited to the dir entry.

Follow-up

After this ships in a provider release, a small coder/coder PR will append an update to the dir row in the 2.29–2.34 ESR upgrade notes (keeping the original text) saying dir was un-deprecated in that release.

Decision log

• First version of this PR only removed the "breaks Coder Desktop file sync" sentence and kept the deprecation.
• @matifali asked whether dir should be un-deprecated instead. Git history showed dir was not deprecated before chore: warn when coder_agent dir breaks Desktop file sync #507, and chore: warn when coder_agent dir breaks Desktop file sync #507's only stated reason was file sync (DEVEX-227). No separate tracking issue exists.
• @matifali: "IIRC yes" (file sync was the only reason). @code-asher: file sync was the only reported issue; plain scp still resolves ~/ against dir. @zenithwolf1000 (chore: warn when coder_agent dir breaks Desktop file sync #507 author): "let's clean up the deprecation warning altogether".
• The scp behavior is an OpenSSH client assumption that the server cannot detect, and devcontainers hit it independently of dir, so removing dir would not remove it. Decision: un-deprecate and document absolute paths.
• No min-version gate: with the deprecation gone there is no plan-time warning to time. Users on pre-fix Desktop clients get file sync working by updating Desktop.
• ESR 2.29–2.34 upgrade note: keep the original row as history and append an update line in a follow-up coder/coder PR once the provider version is known.

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🤖 Opened by Coder Agents on behalf of @aqandrew.

[linear-code]

DESK-2

[aqandrew]

Good catch — you're right that as written this only changes the wording and the provider still emits a deprecation warning.

I dug into the history: dir wasn't deprecated before #507. That PR added the Deprecated: field, the description warning, and the WarnDirNotHome validator together, and its stated reason was Coder Desktop file-sync compatibility (Refs DEVEX-227). I couldn't find any other rationale or a separate tracking issue for the deprecation.

Since the file-sync problem is now fixed (coder/mutagen#10, released and bundled into both Desktop clients), the original justification for the deprecation is gone. So the cleaner change is to fully un-deprecate dir rather than just reword: revert #507 entirely — drop the Deprecated: field, the description warning, and the ValidateFunc, delete WarnDirNotHome and its test, and regenerate the docs.

Before I expand this PR to do that: was file sync the only reason we deprecated dir, or is there a separate intent to keep steering people to $HOME (e.g. Desktop/SFTP consistency)? If file sync was the sole reason, I'll turn this into a full revert of #507. If we want to keep it deprecated for another reason, I'll leave the deprecation and put that reason in the message instead.

🤖 Posted by Coder Agents on behalf of @aqandrew.

[matifali]

Before I expand this PR to do that: was file sync the only reason we deprecated dir, or is there a separate intent to keep steering people to $HOME (e.g. Desktop/SFTP consistency)

IIRC yes. But lets confirm from @zenithwolf1000 and @ash

[code-asher]

File sync was the only reported issue (as far as I know), but it would be a problem with plain scp still and any other tool that uses scp.

Whether any users will actually try that and run into the issue though...I have no idea. One would think though that someone somewhere will probably use scp at some point. 😆

[aqandrew]

@code-asher Agreed, that matches what we traced: modern OpenSSH scp strips ~/ client-side (prepare_remote_path() assumes cwd is the home dir), so scp host:~/foo lands in dir. coder/mutagen#10 only fixes Mutagen.

I think it's a small problem, though, and not a reason to keep dir deprecated:

• Only ~/ paths are affected. Relative paths landing in dir is intended ("SFTP and SCP now respect the workspace agent dir setting" in the 2.29–2.34 ESR notes). Absolute paths and scp -O work correctly.
• The server can't fix it. It receives foo for both ~/foo and foo, so the only full fix would be starting SFTP in $HOME again, undoing that intended change.
• Deprecating dir wouldn't remove it. Devcontainer workspaceFolder causes the same behavior independently of coder_agent.dir.

Proposal: un-deprecate dir (revert #507) and replace the warning with a short note in its description to use absolute paths for scp/SFTP. I'll wait for @zenithwolf1000 to confirm before updating the PR.

🤖 Posted by Coder Agents on behalf of @aqandrew.

[zenithwolf1000]

@aqandrew @matifali reminder to update any external docs and update customer material to match before the next release, since this was quite an unpopular deprecation plan.

[matifali]

@aqandrew lets also plan a release for the provider.

[aqandrew]

@aqandrew @matifali reminder to update any external docs and update customer material to match before the next release, since this was quite an unpopular deprecation plan.

@aqandrew lets also plan a release for the provider.

Will do x2!

[matifali]

@linear create an issue for both and set deadline of October 22.
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