Fix the Go samples module build

[rinceyuan]

go/samples is a separate module that consumes the SDK through a replace github.com/github/copilot-sdk/go => ../ directive, so it needs go.sum entries for the SDK's own dependencies. Two are missing, and go build ./... in that directory fails.

Reproducing on main

$ cd go/samples && go build ./...
../copilot_request_handler.go:18:2: missing go.sum entry for module providing package
github.com/coder/websocket (imported by github.com/github/copilot-sdk/go); to add:
        go get github.com/github/copilot-sdk/go@v0.0.0

go vet ./... fails identically. The SDK requires the package, but the samples module never learned about it:

	coder/websocket
go/go.mod	required, v1.8.15
go/go.sum	2 entries
go/samples/go.sum	0 entries
go/samples/go.mod	not listed

How it drifted

Date	Change
2026-05-12	go/samples go.mod/go.sum last updated (#1252)
2026-06-23	#1689 added coder/websocket to the SDK — samples not updated

No workflow builds go/samples, so nothing caught it. The only CI reference to a samples directory is the step that refreshes the nodejs samples lockfile in update-copilot-dependency.yml.

The change

go mod tidy in go/samples, which adds the two indirect dependencies the SDK pulls in, with their hashes:

+ github.com/coder/websocket v1.8.15 // indirect
+ github.com/ebitengine/purego v0.10.1 // indirect

Both are already direct requirements of go/go.mod at exactly these versions.

Verification

$ cd go/samples && go build ./... && go vet ./...      # both exit 0

The main module is untouched and still builds:

$ git diff --stat -- go/go.mod go/go.sum
                      # (no output)
$ cd go && go build ./...                              # exit 0

Scope

Six added lines across the samples module's go.mod and go.sum; no deletions, no source changes, and no change to the main module. This only restores the build — I have not tried to add CI coverage for the samples, since where that belongs felt like your call.

[Copilot]

🟢 Approval recommended

The dependency versions and checksums match the main Go module and correctly restore sample-module resolution.

Pull request overview

Restores the standalone Go samples module’s build by declaring and checksumming SDK transitive dependencies.

Changes:

• Adds indirect requirements for websocket and purego.
• Adds their module checksums.

File summaries

File	Description
go/samples/go.mod	Declares the missing indirect dependencies.
go/samples/go.sum	Records matching dependency checksums.

Review details

• Files reviewed: 1/2 changed files
• Comments generated: 0
• Review effort level: Balanced

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