cutover endpoint

[insipx]

create an endpoint for the d14n cutover timestamp. closes #3031

[insipx]

This PR is part of a stack of 4 bookmarks:

1. trunk()
2. push-qqtpmktputny
3. push-rmpzuuomqxrs ← this PR
4. push-zwqsrxnyywwx
5. push-tlyurqorvnrq

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Created with jj-stack

[claude]

Claude finished @insipx's task —— View job

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Code Review - February 4, 2026 21:20 UTC

• Read and analyze changed files
• Review code quality and implementation
• Check for bugs and security issues
• Provide feedback

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Review Findings

Critical Issue: Type mismatch in Endpoint implementation

In fetch_d14n_cutover.rs:11, the Endpoint trait is implemented incorrectly:

impl Endpoint for FetchD14nCutover {
    type Output = FetchD14nCutover;  // ❌ Wrong - should be FetchD14nCutoverResponse

This should be:

    type Output = FetchD14nCutoverResponse;

Why this matters:

• The Output associated type should be the response type, not the request struct itself
• All other endpoints follow this pattern (e.g., GetNodes → GetNodesResponse, HealthCheck → HealthCheckResponse)
• This will likely cause compilation errors when the endpoint is actually used, since FetchD14nCutover doesn't implement Message or the necessary response traits
• The proto definition clearly shows FetchD14nCutoverResponse is the response type with timestamp_ns: u64 field

Proto Cache Enhancement:

The proto_cache.rs changes are well-implemented - adding both input and output type lookups to METHOD_LOOKUP is correct since this endpoint uses pbjson_types::Empty as input (which may be reused across multiple endpoints), making output-type lookup necessary.

Minor: Test Coverage

The ignored test is understandable since the service isn't implemented yet. Consider adding a non-ignored test similar to get_nodes.rs:38-41 that validates the grpc_endpoint() returns the correct path (you already have this at line 28-36, which is good).

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[macroscopeapp]

Add FetchD14nCutover endpoint to issue gRPC call to /xmtp.migration.api.v1.D14nMigrationApi/FetchD14nCutover for cutover

Introduce FetchD14nCutover with an empty pbjson_types::Empty request, export it from the d14n module, add xmtp.migration.api.v1 generated types, and update METHOD_LOOKUP to resolve by input or output type.

📍Where to Start

Start with the endpoint definition in fetch_d14n_cutover.rs.

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📊 Macroscope summarized 26d963d. 4 files reviewed, 1 issue evaluated, 0 issues filtered, 1 comment posted. View details

[codecov]

Codecov Report

❌ Patch coverage is 61.53846% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 74.21%. Comparing base (f014a8d) to head (26d963d).

Files with missing lines	Patch %	Lines
..._api_d14n/src/endpoints/d14n/fetch_d14n_cutover.rs	44.44%	10 Missing ⚠️

Additional details and impacted files

@@                  Coverage Diff                  @@
##           push-qqtpmktputny    #3118      +/-   ##
=====================================================
+ Coverage              74.11%   74.21%   +0.09%     
=====================================================
  Files                    448      449       +1     
  Lines                  55717    55741      +24     
=====================================================
+ Hits                   41297    41367      +70     
+ Misses                 14420    14374      -46     

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[macroscopeapp]

🟡 Medium

d14n/fetch_d14n_cutover.rs:11 Output should be FetchD14nCutoverResponse, not FetchD14nCutover. This will cause deserialization failures when decoding the gRPC response.

Suggested change

	type Output = FetchD14nCutover;
	type Output = FetchD14nCutoverResponse;

🚀 Want me to fix this? Reply ex: "fix it for me".