fix(orchestrator): tolerate missing header for legacy templates

[levb]

V1-era templates (UUIDv1 timestamps from early 2025) have a data file at the basic uncompressed path but no header file in storage. After #3015, createDiff reaches them via two paths and both fail:

1. Peer-served current header: !hasEntry for the ancestor, default branch refreshes the ancestor's header, ErrObjectNotExist propagates.
2. Storage-loaded current header: LoadHeader's backfill inserts a zero BuildData{} marker for V3-or-older ancestors, hasEntry is true, but bd.FrameData is per-mapping trimmed so initialFT stays nil and the first read triggers reloadProactive → same ErrObjectNotExist.

Catch both at construction in createDiff:

• !hasEntry refresh returns ErrObjectNotExist → latch the basic upstream as UncompressedFullFrameTable.
• hasEntry with zero bd (the backfill marker) → latch the basic upstream as UncompressedFullFrameTable up front, never refresh.

reloadSourceLocked stays strict: any runtime refresh failure is a race or genuine miss, never a legacy ancestor. Treating it as uncompressed would feed compressed bytes through a raw reader on modern builds.

[codecov]

❌ 2 Tests Failed:

Tests completed	Failed	Passed	Skipped
2981	2	2979	8

View the top 3 failed test(s) by shortest run time

github.com/e2b-dev/infra/tests/integration/internal/tests/api/sandboxes::TestSnapshotTemplateCreateSandbox

Stack Traces | 0s run time

=== RUN   TestSnapshotTemplateCreateSandbox
=== PAUSE TestSnapshotTemplateCreateSandbox
=== CONT  TestSnapshotTemplateCreateSandbox
--- FAIL: TestSnapshotTemplateCreateSandbox (0.00s)

github.com/e2b-dev/infra/packages/shared/pkg/cache::TestRedisCache_Lock_PreventsParallelCallbacks

Stack Traces | 0.48s run time

=== RUN   TestRedisCache_Lock_PreventsParallelCallbacks
=== PAUSE TestRedisCache_Lock_PreventsParallelCallbacks
=== CONT  TestRedisCache_Lock_PreventsParallelCallbacks
    redis_test.go:454: 
        	Error Trace:	.../pkg/redis/tests.go:27
        	            				.../pkg/cache/redis_test.go:454
        	Error:      	Received unexpected error:
        	            	create container: Error response from daemon: Head "https://registry-1.docker..../redis/manifests/8-alpine": received unexpected HTTP status: 502 Bad Gateway
        	Test:       	TestRedisCache_Lock_PreventsParallelCallbacks
--- FAIL: TestRedisCache_Lock_PreventsParallelCallbacks (0.48s)
redis: 2026/06/17 14:31:01 pool.go:426: redis: connection pool: failed to dial after 2 attempts: dial tcp [::1]:1: i/o timeout
redis: 2026/06/17 14:31:01 pool.go:426: redis: connection pool: failed to dial after 2 attempts: dial tcp [::1]:1: i/o timeout

github.com/e2b-dev/infra/tests/integration/internal/tests/proxies::TestMaskRequestHostAPIParameter

Stack Traces | 5.04s run time

=== RUN   TestMaskRequestHostAPIParameter
=== PAUSE TestMaskRequestHostAPIParameter
=== CONT  TestMaskRequestHostAPIParameter
    mask_request_host_test.go:44: Command [python3] output: event:{start:{pid:1119}}
Executing command ls in sandbox ii390s7zecbjwooskg1as
    mask_request_host_test.go:68: Command [cat] output: event:{start:{pid:1120}}
    mask_request_host_test.go:68: Command [cat] output: event:{end:{exited:true  status:"exit status 0"}}
    mask_request_host_test.go:68: Command [cat] completed successfully in sandbox irqc2r1b6y6gc4sz8mm9l
    mask_request_host_test.go:72: Data: 
    mask_request_host_test.go:73: 
        	Error Trace:	.../tests/proxies/mask_request_host_test.go:73
        	Error:      	"" does not contain "Host: localhost:8080"
        	Test:       	TestMaskRequestHostAPIParameter
--- FAIL: TestMaskRequestHostAPIParameter (5.04s)

github.com/e2b-dev/infra/tests/integration/internal/tests/api/sandboxes::TestSnapshotTemplateCreateSandbox/overwritten_snapshot_build_is_served_immediately_on_sandbox_create

Stack Traces | 15.9s run time

=== RUN   TestSnapshotTemplateCreateSandbox/overwritten_snapshot_build_is_served_immediately_on_sandbox_create
=== PAUSE TestSnapshotTemplateCreateSandbox/overwritten_snapshot_build_is_served_immediately_on_sandbox_create
=== CONT  TestSnapshotTemplateCreateSandbox/overwritten_snapshot_build_is_served_immediately_on_sandbox_create
    snapshot_template_test.go:283: 
        	Error Trace:	.../api/sandboxes/snapshot_template_test.go:37
        	            				.../api/sandboxes/snapshot_template_test.go:283
        	Error:      	Not equal: 
        	            	expected: 201
        	            	actual  : 500
        	Test:       	TestSnapshotTemplateCreateSandbox/overwritten_snapshot_build_is_served_immediately_on_sandbox_create
--- FAIL: TestSnapshotTemplateCreateSandbox/overwritten_snapshot_build_is_served_immediately_on_sandbox_create (15.87s)

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[Copilot]

Pull request overview

This PR updates the orchestrator’s diff-construction logic to gracefully handle legacy (V1-era) templates whose ancestor data exists in storage at the basic uncompressed path but whose header file was never uploaded, avoiding restore failures introduced by more aggressive refresh behavior.

Changes:

• In createDiff, treat ErrObjectNotExist from proactive header refresh (when hasEntry=false) as a legacy condition and latch UncompressedFullFrameTable instead of failing.
• In createDiff, detect the zero header.BuildData{} backfill marker (for V3-or-older ancestors) and latch UncompressedFullFrameTable at construction to prevent runtime refresh attempts.
• Extend and adjust tests to cover both legacy-missing-header and backfill-marker scenarios; simplify test helpers to always read testBlockSize.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
packages/orchestrator/pkg/sandbox/build/storage_diff.go	Adds legacy-aware latching behavior in createDiff and clarifies strictness expectations for runtime refresh.
packages/orchestrator/pkg/sandbox/build/storage_diff_test.go	Adds regression tests for missing ancestor headers and backfill markers; refactors read helpers to fixed block size.

---

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[gemini-code-assist]

Code Review

Calling bd.FrameData.CompressionType() directly will cause a nil pointer dereference panic if bd.FrameData is nil, which occurs for uncompressed builds and the zero-valued backfill marker. This call should be safe-guarded by checking if bd.FrameData is non-nil and defaulting to storage.CompressionNone otherwise.

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