refactor(featurebundle): simplify merge surface via MergeBundles/Append helpers

[matdev83]

Reduces duplication in the feature-bundle merge surface so every new FeatureBundle field requires exactly one append line instead of three (length budget + Grow + append + struct field assignment).

What changed

• internal/featurebundle/merge_surface.go:
  • Add MergedFeatureSurface.Append(b) — the single merge point for all slice fields.
  • Add MergeBundles(bundles...) helper that folds bundles in order.
  • Extract buildEnabledFeatureBundles (registry walk) from MergeFeatureSurface; MergeFeatureSurface now delegates to MergeBundles.
  • Drop the manual slices.Grow length-budgeting (premature optimization; append growth is sufficient and far less duplicated).
• internal/featurebundle/merge_surface_test.go (new): cover empty merge, all-field concatenation, and bundle-order preservation across slices.
• docs/feature-bridge-retirement-checklist.md: note the MergeBundles/Append simplification (plus an accuracy fix for the already-merged standardbundle façade deletion).

Verification (PR scoped, in isolation)

• go test ./internal/featurebundle/... — passes (3 new tests: TestMergeBundles_empty, TestMergedFeatureSurfaceAppend_concatenatesAllFields, TestMergeBundles_preservesBundleOrderAcrossSlices).
• go vet ./internal/featurebundle/... — clean.
• go build ./... — passes; consumers (runtimebundle, standardplugins) build and test cleanly.

No behavior change; merge order and field contents are preserved.

Fourth of the PRs splitting the post-review cleanup changes on the local working tree.

[coderabbitai]

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Run ID: 7d4522af-5244-46e8-9274-aeff64830343

📥 Commits

Reviewing files that changed from the base of the PR and between 69941c1 and 2a78ea2.

📒 Files selected for processing (3)

• docs/feature-bridge-retirement-checklist.md
• internal/featurebundle/merge_surface.go
• internal/featurebundle/merge_surface_test.go

📜 Recent review details

⏰ Context from checks skipped due to timeout. (1)

• GitHub Check: qa

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📓 Path-based instructions (4)

**/*

📄 CodeRabbit inference engine (Custom checks)

Do not introduce hardcoded credentials, API keys, tokens, private keys, passwords, production secrets, or sensitive internal URLs.

Files:

• docs/feature-bridge-retirement-checklist.md
• internal/featurebundle/merge_surface_test.go
• internal/featurebundle/merge_surface.go

**/*.go

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**/*.go: For server, CLI, worker, or network Go code, ensure context.Context is propagated correctly, cancellation is respected, and new goroutines cannot leak indefinitely.
Do not make accidental public API breaks in Go code: under pkg/** or anywhere exported Go identifiers are changed, warn if the PR changes exported types, function signatures, error behavior, JSON fields, CLI flags, config keys, or documented behavior without clearly explaining the compatibility impact.

Files:

• internal/featurebundle/merge_surface_test.go
• internal/featurebundle/merge_surface.go

---

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**/*.go: Review as production Go code. Prioritize correctness, race conditions, goroutine leaks, context cancellation, timeout handling, error wrapping, nil-pointer risks, resource cleanup, defer placement, API compatibility, interface design, dependency boundaries, and testability. Avoid generic style comments when gofmt/golangci-lint already covers the issue.

Files:

• internal/featurebundle/merge_surface_test.go
• internal/featurebundle/merge_surface.go

internal/**

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Files:

• internal/featurebundle/merge_surface_test.go
• internal/featurebundle/merge_surface.go

**/*_test.go

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**/*_test.go: Review tests for meaningful assertions, table-driven coverage, race-prone tests, t.Parallel misuse, nondeterminism, leaked goroutines, real network or filesystem dependencies, fragile sleeps, and missing edge cases. Prefer testing observable behavior over implementation details.

Files:

• internal/featurebundle/merge_surface_test.go

🧠 Learnings (1)

📚 Learning: 2026-07-01T22:57:42.953Z

Learnt from: matdev83
Repo: matdev83/go-llm-interactive-proxy PR: 101
File: pkg/lipsdk/scope/context.go:0-0
Timestamp: 2026-07-01T22:57:42.953Z
Learning: In this repository, when defining unexported Go `context` key constants of type `ctxKey int` (e.g., `const ( kFoo ctxKey = iota + N )`), preserve the `iota + <offset>` pattern and keep the existing `<offset>` values rather than simplifying to plain `iota`. These per-package offsets are part of the repo-wide convention to avoid key collisions across packages, and each such constant set should include a short explanatory comment (for example: “offset avoids collision with other packages' context keys”).

Applied to files:

• internal/featurebundle/merge_surface_test.go
• internal/featurebundle/merge_surface.go

🔇 Additional comments (3)

docs/feature-bridge-retirement-checklist.md (1)

32-32: LGTM!

internal/featurebundle/merge_surface.go (1)

44-106: LGTM!

internal/featurebundle/merge_surface_test.go (1)

1-257: LGTM!

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📝 Walkthrough

Summary by CodeRabbit

• New Features

  • Added support for combining multiple feature bundles into one merged surface.
  • Improved bundle handling so feature hooks and observers are appended in order.

• Bug Fixes

  • Updated startup flow to use the current standard plugin installation path.
  • Removed an outdated bridge component from the retirement checklist.

• Tests

  • Added coverage for empty merges, bundle concatenation, and order preservation.

Walkthrough

Refactors internal/featurebundle/merge_surface.go to introduce MergedFeatureSurface.Append and MergeBundles for incremental bundle merging, delegating MergeFeatureSurface to a new buildEnabledFeatureBundles helper. Adds unit tests for the new merge API and updates the bridge retirement checklist documentation accordingly.

Changes

Feature bundle merge refactor

Layer / File(s)	Summary
Append and MergeBundles implementation internal/featurebundle/merge_surface.go	Adds Append method and MergeBundles function for incremental slice-field concatenation; refactors MergeFeatureSurface to use new buildEnabledFeatureBundles helper, removing prior slices.Grow-based preallocation logic.
Unit tests for merge behavior internal/featurebundle/merge_surface_test.go	Adds no-op test doubles and three tests validating empty merges, field concatenation across bundles, and preserved bundle order.
Retirement checklist documentation update docs/feature-bridge-retirement-checklist.md	Updates the “Bridge status” line to reflect the merge surface simplification, façade package deletion, and direct standardplugins.InstallStandardBundleOn call.

Estimated code review effort: 2 (Simple) | ~15 minutes

Possibly related PRs

• matdev83/go-llm-interactive-proxy#114: Both PRs modify the merge implementation and APIs in internal/featurebundle/merge_surface.go.

🚥 Pre-merge checks | ✅ 8

✅ Passed checks (8 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the featurebundle merge-surface refactor and the new MergeBundles/Append helpers.
Description check	✅ Passed	The description clearly matches the refactor, tests, and docs updates in the changeset.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
No Secrets	✅ Passed	Modified files contain only merge/refactor code and docs text; no hardcoded secrets, tokens, passwords, private keys, or sensitive URLs found.
Context Propagation	✅ Passed	The PR only refactors synchronous slice concatenation; no new goroutines, and existing bootstrap ctx still flows into tracing/shutdown paths.
No Accidental Public Api Break	✅ Passed	Only new helpers were added in an internal package; no existing exported signatures or pkg/** fields changed, and the PR states behavior is preserved.

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