feat(sandbox): workspace snapshot persistence + web app builder tile

[rafavalls]

What

Two features shipped together:

1. Sandbox snapshot persistence

Every running sandbox now auto-saves its full workspace state (a tar of the workdir, including .git and node_modules) to a blob store. On cold start, VM_START restores from the snapshot before cloning — so state survives pod evictions with no npm install penalty.

Store adapters:

• LocalFsStore — for local dev / host runner (writes to <DATA_DIR>/sandbox-snapshots/)
• S3Store — for prod (bucket + IRSA, reads SANDBOX_SNAPSHOTS_BUCKET / region / prefix / endpoint env vars)

Daemon routes (packages/sandbox/daemon/routes/snapshot.ts):

• GET /_decopilot_vm/snapshot/create — streams a tar of the workdir, excluding ./tmp
• POST /_decopilot_vm/snapshot/restore — atomic restore: extracts to a temp dir, then rename-swaps on success so a failed restore never leaves a partial workdir

Idle poller (apps/mesh/src/sandbox/snapshot-saver.ts):

• Polls on setInterval; saves only when activity has occurred since the last save (watermark-based)
• Re-entry guard prevents overlapping ticks
• Sweep on shutdown so the final state is always captured

VM start (apps/mesh/src/tools/vm/start.ts):

• Before the daemon clone, checks the store for a snapshot and streams it to /snapshot/restore
• Restore errors fall through silently so a fresh clone is always the fallback

Helm (deploy/helm/studio/):

• sandboxSnapshots values block wires all env vars into the mesh deployment

2. Web app builder tile

One-click "build a web app" entry point on the home screen (feat(home): Web app tile) — launches a vibecode session from a deco template.

3. Plain cloneUrl support

Agents can now specify a cloneUrl (plain HTTPS, no GitHub OAuth) in addition to githubRepo. Both harnesses (decopilot and claude-code) and VM_START handle both source types.

4. Daemon spawn reliability fixes

• spawnSetupStep now uses child_process.spawn (not node-pty / Bun.spawn) — avoids forkpty failures on macOS and supports uid/gid drops
• PTY fallback to pipe for the dev-server process
• TRANSIENT_ERRORS expanded to catch posix_spawnp failed, posix_spawn failed, Resource temporarily unavailable
• spawnSetupStep always resolves (never rejects) — spawn errors surface as exit code 1 + onChunk message, preserving the promise contract at all call sites

Test plan

• bun test packages/sandbox/daemon/routes/snapshot.test.ts — create/restore round-trip, tmp exclusion, malformed tar, missing body
• bun test apps/mesh/src/sandbox/snapshot-saver.test.ts — idle detection, re-entry guard, watermark timing
• End-to-end: open any agent, edit a file, wait for idle save, kill the pod, restart, confirm edits restored within ~5s (no npm install on cold start) — runnable locally with host runner + LocalFsStore

🤖 Generated with Claude Code

[cubic-dev-ai]

No issues found across 1 file

_{Re-trigger cubic}

[cubic-dev-ai]

1 issue found across 2 files (changes from recent commits).

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="SANDBOX_PERSISTENCE.md">

<violation number="1" location="SANDBOX_PERSISTENCE.md:121">
P2: Create endpoint returns 204 for empty workdir, but snapshot-saver unconditionally pipes the response body to store.put(). A 204 has no body — results in a malformed snapshot entry.</violation>
</file>

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

Re-trigger cubic</sub>

[cubic-dev-ai]

P2: Create endpoint returns 204 for empty workdir, but snapshot-saver unconditionally pipes the response body to store.put(). A 204 has no body — results in a malformed snapshot entry.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At SANDBOX_PERSISTENCE.md, line 121:

<comment>Create endpoint returns 204 for empty workdir, but snapshot-saver unconditionally pipes the response body to store.put(). A 204 has no body — results in a malformed snapshot entry.</comment>

<file context>
@@ -0,0 +1,315 @@
+  - cd <repoDir>
+  - spawn `tar -cf - --exclude=./tmp .`
+  - pipe tar's stdout into the HTTP response body
+  - returns 204 if repoDir is empty (nothing to snapshot yet)
+
+POST /_decopilot_vm/snapshot/restore
</file context>

[github-actions]

Release Options

Suggested: Patch (2.335.1) — based on docs: prefix

React with an emoji to override the release type:

Reaction	Type	Next Version
👍	Prerelease	2.335.1-alpha.1
🎉	Patch	2.335.1
❤️	Minor	2.336.0
🚀	Major	3.0.0

Current version: 2.335.0

Note: If multiple reactions exist, the smallest bump wins. If no reactions, the suggested bump is used (default: patch).

[cubic-dev-ai]

4 issues found across 8 files (changes from recent commits).

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="apps/mesh/src/sandbox/sandbox-store/local-fs-store.ts">

<violation number="1" location="apps/mesh/src/sandbox/sandbox-store/local-fs-store.ts:44">
P2: Temp filename needs stronger uniqueness. Same-ms concurrent puts can collide. Add random suffix.</violation>
</file>

<file name="packages/sandbox/daemon/entry.ts">

<violation number="1" location="packages/sandbox/daemon/entry.ts:301">
P2: Snapshot root wrong. It points at `repoDir`, not full workdir. Files outside `/app/repo` never save/restore, and `--exclude=./tmp` no longer matches intended path. Wire snapshot handlers to workspace root.</violation>
</file>

<file name="packages/sandbox/daemon/routes/snapshot.ts">

<violation number="1" location="packages/sandbox/daemon/routes/snapshot.ts:119">
P1: Restore untars straight into live repoDir. Tar can fail after writing some files, so repoDir can end up half-restored. Extract into a temp dir and swap only on success (or clean repoDir on failure).</violation>

<violation number="2" location="packages/sandbox/daemon/routes/snapshot.ts:148">
P1: Exit-code check alone too weak for tar integrity. Truncated archive can still exit 0 and look successful, but restore misses files. Add integrity verification (for example checksum/size metadata) before returning ok.</violation>
</file>

<sub>Tip: Review your code locally with the cubic CLI to iterate faster.

Re-trigger cubic</sub>

[cubic-dev-ai]

P1: Exit-code check alone too weak for tar integrity. Truncated archive can still exit 0 and look successful, but restore misses files. Add integrity verification (for example checksum/size metadata) before returning ok.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At packages/sandbox/daemon/routes/snapshot.ts, line 148:

<comment>Exit-code check alone too weak for tar integrity. Truncated archive can still exit 0 and look successful, but restore misses files. Add integrity verification (for example checksum/size metadata) before returning ok.</comment>

<file context>
@@ -0,0 +1,159 @@
+      child.on("exit", (code, signal) => resolve({ code, signal }));
+    });
+
+    if (exit.code !== 0) {
+      return jsonResponse(
+        {
</file context>

[cubic-dev-ai]

4 issues found across 15 files (changes from recent commits).

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="apps/mesh/src/sandbox/snapshot-saver.ts">

<violation number="1" location="apps/mesh/src/sandbox/snapshot-saver.ts:112">
P2: Record save watermark at snapshot start, not upload finish. Finish time can hide activity that happened during save.</violation>

<violation number="2" location="apps/mesh/src/sandbox/snapshot-saver.ts:128">
P2: Add re-entry guard around tick. setInterval can overlap async runs. Duplicate saves and lastSavedAt races can happen.</violation>
</file>

<file name="apps/mesh/src/sandbox/sandbox-store/index.ts">

<violation number="1" location="apps/mesh/src/sandbox/sandbox-store/index.ts:36">
P2: Boolean env parse too strict. `"true"` ignored, path-style may stay off. Accept `"true"` and `"1"`.</violation>
</file>

<file name="apps/mesh/src/tools/vm/start.ts">

<violation number="1" location="apps/mesh/src/tools/vm/start.ts:320">
P1: Best-effort restore not actually best-effort. Catch restore errors in onDaemonReady so VM_START can continue to fresh clone.</violation>
</file>

<sub>Tip: Review your code locally with the cubic CLI to iterate faster.

Re-trigger cubic</sub>

[cubic-dev-ai]

1 issue found across 9 files (changes from recent commits).

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="packages/mesh-sdk/src/types/virtual-mcp.ts">

<violation number="1" location="packages/mesh-sdk/src/types/virtual-mcp.ts:172">
P1: Restrict cloneUrl protocol to https. `.url()` alone accepts insecure schemes like `http`, so token-in-URL clones can leak credentials. Add protocol check.</violation>
</file>

<sub>Tip: Review your code locally with the cubic CLI to iterate faster.

Re-trigger cubic</sub>

[cubic-dev-ai]

2 issues found across 2 files (changes from recent commits).

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="SANDBOX_PERSISTENCE.md">

<violation number="1" location="SANDBOX_PERSISTENCE.md:121">
P2: Create endpoint returns 204 for empty workdir, but snapshot-saver unconditionally pipes the response body to store.put(). A 204 has no body — results in a malformed snapshot entry.</violation>
</file>

<file name="packages/sandbox/daemon/routes/snapshot.ts">

<violation number="1" location="packages/sandbox/daemon/routes/snapshot.ts:148">
P1: Exit-code check alone too weak for tar integrity. Truncated archive can still exit 0 and look successful, but restore misses files. Add integrity verification (for example checksum/size metadata) before returning ok.</violation>
</file>

<sub>Tip: Review your code locally with the cubic CLI to iterate faster.

Re-trigger cubic</sub>