fix: apply log_level directive to env filter for tracing subscriber

[gaius-qi]

The tracing subscriber previously used EnvFilter::from_default_env() together with with_max_level(log_level). When RUST_LOG was unset, EnvFilter defaulted to ERROR and overrode the configured log_level, making it ineffective.

Summary by CodeRabbit

• Chores
  • Updated internal logging configuration setup for improved consistency and maintainability.

[coderabbitai]

Walkthrough

The tracing subscriber configuration in the main entry point was refactored to use a single EnvFilter directive for log-level limiting, consolidating the previous approach that relied on both with_env_filter() and with_max_level() methods.

Changes

Cohort / File(s)	Summary
Tracing Configuration modelexpress_server/src/main.rs	Refactored EnvFilter construction to combine default environment filter with log-level directive via add_directive(), replacing separate with_max_level() call.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Poem

🐰 A hop through logs, now filtered clean,
Where directives reign supreme,
No more conflicting calls to sort,
Just one EnvFilter to report! ✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and specifically describes the main change: applying a log_level directive to the env filter for the tracing subscriber configuration.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
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.

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@modelexpress_server/src/main.rs`:
- Around line 51-53: The current logging setup unconditionally adds a directive
via EnvFilter::from_default_env().add_directive(log_level.into()) which
overrides RUST_LOG; change to use EnvFilter::from_env_lossy() combined with
setting the fallback via with_default_directive(log_level.into()) so the
configured log_level is only applied when RUST_LOG is unset/invalid. Locate the
EnvFilter usage (EnvFilter::from_default_env and add_directive) and replace the
construction with EnvFilter::from_env_lossy(...) / or use
EnvFilter::from_env_lossy() and pass it into
FmtSubscriber::builder().with_env_filter(...), or use the builder helper
with_default_directive(log_level.into()) before calling from_env_lossy to ensure
the configured level is a default rather than an override.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: c682f952-3cc0-4479-85e0-36262b2aa136

📥 Commits

Reviewing files that changed from the base of the PR and between 94b8e75 and 0a5586f.

📒 Files selected for processing (1)

• modelexpress_server/src/main.rs

[gaius-qi]

@nicolasnoble @AndyDai-nv @nv-hwoo @KavinKrishnan @zhengluo-nv PTAL