build: enhance Cargo profiles (release-with-debug + neuromod alignment) + service registry unit tests

[rmems]

Summary

Enhance the existing Cargo profiles for better consistency with other Limen-Neural crates (especially neuromod) and lock down unit-test coverage for the service registry’s enable/disable and empty-registry paths on the stub backend.

Cargo profiles

The four built-in profiles are already present in Cargo.toml and documented in the README, but they are intentionally conservative. This issue formalizes a small, deliberate enhancement:

Current state

• [profile.dev] – opt-level 0, full debug, overflow checks
• [profile.release] – opt-level 3, thin LTO, strip debuginfo
• [profile.test] – matches dev (debuggable + safe)
• [profile.bench] – matches release

Proposed changes

1. Add custom profile (matches neuromod pattern and is useful for a 1 kHz tick-loop daemon):

   [profile.release-with-debug]
   inherits = "release"
   debug = true

   Use with cargo build --profile release-with-debug when you need symbols for perf / flamegraphs / tracing without falling back to a full debug build.

2. Optional tightenings (discuss / apply only if compile-time cost is acceptable):

   • [profile.release]: lto = true (or keep "thin") + codegen-units = 1
   • [profile.dev]: opt-level = 1 + incremental = true (faster local runs of the daemon)
   • [profile.bench]: inherits = "release"

3. Update the README “Cargo profiles” table and the comment block in Cargo.toml so the intent stays explicit.

Keep the conservative philosophy: no extreme knobs that over-promise for a headless inference daemon.

Service registry unit tests

(Original intent preserved)

Registry is config-driven ([[services]] in daemon.toml). Coverage stays on the stub backend path.

1. Locate registry construction / enable flags in src/registry.rs (or equivalent).
2. Unit tests for:
   • empty services list
   • enabled service present
   • disabled service not active
3. Keep tests free of network / ZMQ.

Acceptance criteria

• [profile.release-with-debug] added and documented
• README + Cargo.toml comments updated to reflect final profile choices
• cargo build, cargo build --release, cargo test, and cargo build --profile release-with-debug all succeed
• New unit tests cover enable/disable + empty-registry paths
• cargo test green without optional features
• No new dependencies without justification
• Assignee: @rmems

Relationships

• Milestone: v0.2 — Stub quality
• Sibling: REVIEW.md quality gate
• Related Linear: build: enhance Cargo profiles (release-with-debug + neuromod alignment) + service registry unit tests #30

Out of scope

• Real service adapter implementations
• Cross-repo IPC integration
• Aggressive “max-opt / inferno” profiles or FPGA-specific profiles (future issues)

[linear-code]

LIM-1010

[rmems]

Issue rewritten by Grok (team lead) + collaborators (Chaos Goblin / Cosmic Trickster / Mad Scientist / Harper / Benjamin / Lucas).

Original title mixed a pure testing task with an incomplete “alongside new cargo profiles” note. The four built-in profiles already existed and were documented; this update properly scopes the issue to:

1. Add the useful custom [profile.release-with-debug] (aligned with neuromod) for profiling the high-rate tick loop.
2. Optionally tighten the existing profiles while respecting the conservative philosophy.
3. Keep the original service-registry unit-test work.

Updated both this GitHub issue and the linked Linear issue LIM-1010 for consistency.

Ready for implementation when you are.