…#688)

copy_in saves the uploaded tar as a binary blob instead of extracting

## Bug

`PUT /v1/{prefix}/boxes/{id}/files` (the runner handler for SDK
`copy_in`)
silently broke both single-file and directory uploads:

```
copy_in("host.txt", "/root/hello.txt")
  → /root/hello.txt = raw tar bytes (ustar header + payload), not the file
copy_in("host_dir/", "/root/flatdest/")
  → /root/flatdest/boxlite-upload-XXXXXX.tar = the directory as one big tar
```

Root cause: the SDK Rust REST client serialises the source as a tar
archive
in the body. The runner buffered it to `<tmp>/boxlite-upload-*.tar` and
called `Boxlite.CopyInto(tarPath, dest)`, which treats `src` as a
literal
filesystem path — so the tar archive itself was the "file" that landed
in
the guest.

## Fix

Extract the uploaded tar at the runner before calling `CopyInto`:

| Archive shape | Behaviour |
|---|---|
| 1 regular file, no other entries | write at `dest` (single-file
copy_in) |
| Multiple entries / dirs / symlinks / specials | `unpack` into `dest`
(directory copy_in) |
| Any entry with `..` in path | reject (zip-slip guard) |

## Test plan — two-sided verified

Pin: `scripts/test/e2e/cases/test_files_io.py`

Stack: local e2e. Runner binary swapped between main and PR builds.

| Case | Pre-fix (main) | Post-fix (this PR) |
|---|---|---|
| `test_copy_in_text_roundtrips_byte_exact` (host writes `"üñîçødé\n"`,
copy_in, guest cat) | `cat` returned raw tar archive text + ustar header
(`'hello.txt…ustar…<payload>'`) — file at expected path didn't exist |
**byte-exact payload** at `/root/hello.txt` |
| `test_copy_in_directory_include_parent_false` (copy_in dir with nested
files; `find -type f`) | only `/root/flatdest/boxlite-upload-XXXXXX.tar`
(the raw tar landed as one file) | **both `top.txt` and `sub/deep.txt`**
under `/root/flatdest/` |
| `test_copy_in_overwrite_false_rejects_conflict` | empty | empty —
runner-side extract always uses `O_TRUNC`. `overwrite=False` policy not
honoured on REST yet |
| `test_copy_out_binary_roundtrips_sha256` | `IsADirectoryError` on
host_dest | `IsADirectoryError` on host_dest — SDK Rust copy_out has the
mirror bug (raw tar saved as dir) |

This PR closes the two known-broken copy_in paths (single file +
directory). The two residual failures are different bugs:
- `overwrite=False` needs the tar-extract path to respect the option;
minor follow-up (5 lines in extract_tar).
- `copy_out` needs the SAME fix on the SDK side (the SDK currently saves
the runner's tar response without extracting). That's a Rust-SDK PR
(#692), scope of a separate change.


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Improvements**
* Enhanced file upload handling to support efficient transfers of both
individual files and directory structures.

* **Tests**
* Added comprehensive end-to-end tests for file operations, verifying
data integrity, text preservation, binary round-tripping, recursive
directory handling, and overwrite behavior.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

#710)

add 5 e2e cases pinning REST contracts not covered today

## Coverage gaps

Three classes of behaviour run through the SDK → API → Runner → VM
chain but had no e2e pin on the chain itself; bugs in any one of them
would silently regress through `make test:integration:*` (which only
exercises local-FFI):

```
1. CLI detach lifecycle — `boxlite run -d` returns, CLI process exits,
   does a fresh CLI process still see / exec the box?
   FFI side  src/boxlite/tests/detach.rs, recovery.rs  ✓
   E2E side  scripts/test/e2e/cases/                    ✗
2. Execution.attach / reattach contract — bogus exec_id should be a
   typed client error; reattach to a completed exec should return a
   usable handle.
   Runner side  apps/runner/.../boxlite_exec_attach_test.go  ✓
   SDK <-> API  end-to-end                                    ✗
3. host bind mount via REST — the cloud runtime intentionally dropped
   host bind mounts (#639); REST callers passing host paths must
   silently no-op, no /mnt/<x> in the guest.
   FFI surface  src/boxlite/tests/mount_security.rs  ✓
   REST contract                                      ✗
```

## Cases shipped

```
scripts/test/e2e/cases/test_cli_detach_recovery.py   (2 cases)
scripts/test/e2e/cases/test_exec_attach.py           (2 cases)
scripts/test/e2e/cases/test_volume_readonly.py       (1 case)
```

5 cases total. Author also dropped 6 cases from this branch's earlier
incarnation that were already committed alongside their respective
fix PRs (#686 / #688 / #689 / #691 / #692 / #696), so the diff is
strictly net-new coverage.

## Test plan — run against current main

Stack: local e2e, runner unchanged, no source edits.

| Case | Result | Notes |
|---|---|---|
| `test_detached_box_exec_propagates_exit_code_on_fresh_cli` | ✅ PASS |
exit-code passthrough across CLI processes |
| `test_detached_box_survives_cli_exit_and_is_reusable` | ⚠️ XFAIL
(strict) | reaches step 3 (`boxlite exec <id> echo still-alive`) then
hits the stdout-drop race that #563 fixes — marker drops when #563 lands
|
| `test_attach_with_bogus_id_is_typed_error` | ✅ PASS | bogus exec_id →
typed `Exception` (not 5xx, not silent) |
| `test_reattach_after_original_completes` | ⚠️ XFAIL (strict) | same
stdout-drop race (#563) on the original exec's `out=='first-output'`
assertion |
| `test_host_bind_mount_via_rest_is_silently_ignored` | ✅ PASS | the box
created with `volumes=[(host_dir, "/mnt/ro", True)]` reports
`MOUNT_LINE=<none>` from `/proc/mounts` and the host marker file is
untouched — REST silently dropped the host path |

The 2 XFAILs are tied to #563 (`fix(go-sdk): fold stream drain into
Execution.Wait`). Once #563 merges, both xfails flip xpass-strict, the
markers come off, and the suite is 5/5 green. No additional fix work is
needed in this PR.

🤖 Generated with [Claude Code](https://claude.com/claude-code)


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Tests**
* Added end-to-end tests verifying CLI detach survival and box
reusability across fresh CLI processes, including exit code propagation
tests.
* Added end-to-end tests for SDK reattach functionality, validating
session state after execution completion.
* Added end-to-end test confirming proper host bind mount handling
during REST execution.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>