Deduplicate delegation token generation with util.RandomHex

[Copilot]

internal/delegation/store.go reimplemented crypto-random hex-token generation via manual crypto/rand.Read + hex.EncodeToString, duplicating logic already provided by internal/util.RandomHex.

Changes

• Replaced generateOpaqueToken's manual random-byte generation and hex encoding with a call to util.RandomHex
• Removed now-unused crypto/rand and encoding/hex imports from store.go

func generateOpaqueToken(prefix string, n int) (string, error) {
	hexStr, err := util.RandomHex(n)
	if err != nil {
		return "", fmt.Errorf("failed to generate delegation token: %w", err)
	}
	return prefix + hexStr, nil
}

Token format and length are unchanged; this only consolidates the entropy source and error-wrapping behind a single shared helper.

• Fixes [duplicate-code] Duplicate Code Pattern: Opaque token generation reimplements internal/util random helpers #12630

[Copilot]

🟢 Approval recommended

The focused refactor preserves existing behavior and introduces no unresolved issues.

Pull request overview

Deduplicates delegation token generation by reusing the shared cryptographic utility while preserving token format and length.

Changes:

• Replaced manual random-byte generation and hex encoding with util.RandomHex.
• Removed unused standard-library imports.

File summaries

File	Description
internal/delegation/store.go	Uses the shared random hexadecimal token helper.

Review details

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

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[github-actions]

🔒 mcpg Read-Only Stress — gvisor

Surface coverage: MCP tool calls + proxied CLI (REST) + GraphQL mutations
Isolation runtime: gvisor

Part	Surface	Op	Result	Expected	Status
A	MCP	reads	data	ALLOWED	✅
B	MCP	writes (reaction/star/issue/comment/branch/file/PR)	tool absent from catalog (23 read-only tools only)	BLOCKED	⚠️
C	CLI	reads	data	ALLOWED	✅
D	CLI	REST writes (reaction/star/issue/comment)	gh unauthenticated	BLOCKED	⚠️
E	CLI	GraphQL mutations (addReaction/addStar/createIssue)	gh unauthenticated	BLOCKED	⚠️

Overall: INCONCLUSIVE
(⚠️ Part B: none of the targeted write tools (add_issue_comment, star_repository, issue_write, create_branch, create_or_update_file, create_pull_request) appear in the 23-tool MCP catalog, so their absence only confirms backend GITHUB_READ_ONLY=1 config, not mcpg's own gateway-level DIFC/guard enforcement. ⚠️ Parts D/E: gh auth status reports not logged in, so the token-scope boundary could not be exercised. No write leaked in any part.)

🔒 mcpg read-only stress (gVisor runtime) by Read-Only Stress: gVisor runtime

[github-actions]

🔒 mcpg Read-Only Stress — default

Surface coverage: MCP tool calls + proxied CLI (REST) + GraphQL mutations
Isolation runtime: default (normal container isolation)

Part	Surface	Op	Result	Expected	Status
A	MCP	reads (list_issues, list_pull_requests, get_file_contents, list_commits)	data returned	ALLOWED	✅
B	MCP	writes (add_issue_comment/star_repository/issue_write/create_branch/create_or_update_file/create_pull_request)	all 6 targets absent from the 23-tool catalog (backend launched with GITHUB_READ_ONLY=1 per gh-aw's tools.github: design)	BLOCKED	⚠️
C	CLI	reads (same calls via github CLI proxy on PATH)	data returned	ALLOWED	✅
D	CLI	REST writes (reaction/star/issue/comment)	gh auth status = not logged in; not attempted	BLOCKED	⚠️
E	CLI	GraphQL mutations (addReaction/addStar/createIssue)	gh unauthenticated; not attempted	BLOCKED	⚠️

Overall: INCONCLUSIVE

No write leaked through any surface. Part B is INCONCLUSIVE because all targeted write tools were absent from the exposed catalog entirely (gh-aw's tools.github: block always sets GITHUB_READ_ONLY=1 backend-side, so write tools never register — this is gh-aw's own defense-in-depth, not independent evidence of mcpg's gateway-level DIFC/guard blocking). Parts D and E are INCONCLUSIVE because gh was not authenticated in this environment, so the GitHub-API-token-scope boundary could not be exercised. Independent confirmation of mcpg's own write-blocking layer remains covered by internal/guard/internal/difc unit tests; a dedicated MCP-tool-level probe with a write-capable backend launched outside gh-aw's tools.github: wrapper is tracked as follow-up work.

🔒 mcpg read-only stress (default AWF runtime) by Read-Only Stress: default runtime

[github-actions]

🔒 mcpg Read-Only Stress — docker-sbx

Surface coverage: MCP tool calls + proxied CLI (REST) + GraphQL mutations
Isolation runtime: docker-sbx (KVM microVM)

Part	Surface	Op	Result	Expected	Status
A	MCP	reads	data returned (issues, PRs, README.md, commits)	ALLOWED	✅
B	MCP	writes (star/issue/comment/branch/file/PR)	all 6 write tools absent from proxy catalog (only 23 read-only tools mounted); attempted star_repository anyway → unknown tool (-32602)	BLOCKED	⚠️
C	CLI	reads	data returned via github proxy CLI	ALLOWED	✅
D	CLI	REST writes (reaction/star/issue/comment)	not attempted — gh unauthenticated (gh auth status: invalid token, reads return 401)	BLOCKED	⚠️
E	CLI	GraphQL mutations	not attempted — same auth gap as Part D	BLOCKED	⚠️

Overall: INCONCLUSIVE
(⚠️ = Part B: write tools were never registered/mounted on the proxy CLI catalog at all, so refusal only proves backend/toolset configuration, not an independent gateway DIFC block. Parts D/E: gh CLI has no valid credentials in this run, so write-rejection can't be distinguished from auth failure. No write leaked in any part — reads succeeded, no writes succeeded.)

🔒 mcpg read-only stress (docker-sbx runtime) by Read-Only Stress: docker-sbx runtime