Support scoped relayfile mount paths

[khaliqgant]

Summary

• Teach relayfile-mount to accept repeated --remote-path values and --paths-file for JSON or newline-delimited path lists.
• Run scoped poll mounts under matching local subdirectories so provider prefixes are preserved and large workspaces avoid full /fs/export pulls.
• Cancel sibling scoped mounts when one subtree returns an error.
• Document repeated --remote-path and --paths-file usage.

Rollout note

This daemon change is backward-compatible for existing no-flag and single-root invocations. It should land and be baked into the snapshot before relying on cloud's single multi-path daemon mode. The paired cloud PR also has a fail-closed capability gate: old/ambiguous daemon probes fall back to one daemon per path with a single --remote-path each.

Tests

• go test ./cmd/relayfile-mount ./internal/mountsync

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 94997262-38da-4251-959d-ce658cfeed5e

📥 Commits

Reviewing files that changed from the base of the PR and between a6b2ad5 and f0b7a91.

📒 Files selected for processing (3)

• README.md
• cmd/relayfile-mount/main.go
• cmd/relayfile-mount/main_test.go

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch codex/relayfile-mount-path-filter

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[github-actions]

Relayfile Eval Review

Run: .relayfile/evals/runs/2026-05-23T19-19-40-647Z-HEAD-provider
Mode: provider
Git SHA: 411e9fc

Passed: 4 | Needs human: 0 | Reviewable: 0 | Missing output: 0 | Failed: 0 | Skipped: 0

Human Review Cases

No reviewable human-review cases captured Relayfile output.

[cubic-dev-ai]

1 issue found across 3 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="cmd/relayfile-mount/main.go">

<violation number="1" location="cmd/relayfile-mount/main.go:449">
P1: Per-scope state-file naming is collision-prone, so different remote paths can clobber the same state file.</violation>
</file>

<sub>Reply with feedback, questions, or to request a fix.

Re-trigger cubic</sub>

[cubic-dev-ai]

P1: Per-scope state-file naming is collision-prone, so different remote paths can clobber the same state file.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At cmd/relayfile-mount/main.go, line 449:

<comment>Per-scope state-file naming is collision-prone, so different remote paths can clobber the same state file.</comment>

<file context>
@@ -262,6 +365,94 @@ func runPollingMount(rootCtx context.Context, cfg mountConfig) error {
+	}
+	ext := filepath.Ext(stateFile)
+	base := strings.TrimSuffix(stateFile, ext)
+	suffix := strings.NewReplacer("/", "-", "\\", "-", ":", "-").Replace(strings.Trim(remotePath, "/"))
+	if suffix == "" {
+		suffix = "root"
</file context>

Suggested change

	suffix := strings.NewReplacer("/", "-", "\\", "-", ":", "-").Replace(strings.Trim(remotePath, "/"))
	suffix := base64.RawURLEncoding.EncodeToString([]byte(strings.Trim(remotePath, "/")))

[khaliqgant]

Shadow review (claude-2) — Fix 6 daemon (multi-path scoped sync)

Verified against PR head.

Sibling cancellation ✅ (this was my flag on the earlier draft): runScopedPollingMounts now derives ctx, cancel := context.WithCancel(rootCtx), runs each mount as runSinglePollingMount(ctx, …), and on the first error calls cancel() (propagates to siblings) then drains errCh to completion via the wg.Wait()+close goroutine — so siblings are awaited, not leaked. defer cancel() covers the happy path. Correct hand-rolled errgroup.

Backward-compat ✅: no --remote-path / single / → original single-mount; the cloud side (mount-script --paths-file probe) only emits scoped/multi-path to a daemon that advertises the new capability, else one daemon per path with a single --remote-path each (old-compatible). So the forward-only sequencing risk is gated fail-closed.

--paths-file ✅: readRemotePathsFile is robust (JSON-array or newline + # comments, errors propagate to log.Fatalf). Tested (TestReadRemotePathsFileSupportsJSONAndLines), plus TestNormalizeRemotePathsDedupesRepeatedFlagValues and TestScopedLocalDirKeepsProviderPrefixUnderMountRoot.

One should-add test (non-blocking): the sibling-cancellation teardown itself isn't directly unit-tested — inject one mount that returns an error and assert the others observe ctx cancellation and the func returns firstErr without hanging. It's the riskiest concurrency path and a teardown regression would be silent. (codex-2 is adding this.)

Residual (acknowledged in the issue): per-subtree /fs/export still 413s if any single mounted subtree alone exceeds 128MB — option (a) reduces but doesn't eliminate that; fine for the per-fire persona scopes.