feat(tracing): add performance profiling via tracing crate

Wire up the existing --profile flag with tracing-subscriber to emit
span timings on stderr. Supports MOZART_LOG env var override and
verbose-level-aware filtering. No subscriber is installed when
--profile is off, keeping tracing macros zero-cost.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

1 files changed, 95 insertions, 0 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 5e7b497..9051a53 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -933,6 +933,12 @@ dependencies = [
 ]
 
 [[package]]
+name = "lazy_static"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
+
+[[package]]
 name = "libc"
 version = "0.2.181"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -984,6 +990,15 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "112b39cec0b298b6c1999fee3e31427f74f676e4cb9879ed1a121b43661a4154"
 
 [[package]]
+name = "matchers"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d1525a2a28c7f4fa0fc98bb91ae755d1e2d1505079e05539e35bc876b5d65ae9"
+dependencies = [
+ "regex-automata",
+]
+
+[[package]]
 name = "md5"
 version = "0.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1044,6 +1059,8 @@ dependencies = [
  "serde_json",
  "sha1",
  "tempfile",
+ "tracing",
+ "tracing-subscriber",
 ]
 
 [[package]]
@@ -1072,6 +1089,7 @@ dependencies = [
  "serde",
  "serde_json",
  "tempfile",
+ "tracing",
 ]
 
 [[package]]
@@ -1089,6 +1107,7 @@ dependencies = [
  "serde",
  "serde_json",
  "tempfile",
+ "tracing",
 ]
 
 [[package]]
@@ -1110,6 +1129,7 @@ dependencies = [
  "tar",
  "tempfile",
  "tokio",
+ "tracing",
  "zip",
 ]
 
@@ -1120,6 +1140,15 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "61807f77802ff30975e01f4f071c8ba10c022052f98b3294119f3e615d13e5be"
 
 [[package]]
+name = "nu-ansi-term"
+version = "0.50.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7957b9740744892f114936ab4a57b3f487491bbeafaf8083688b16841a4240e5"
+dependencies = [
+ "windows-sys 0.61.2",
+]
+
+[[package]]
 name = "num-traits"
 version = "0.2.19"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1691,6 +1720,15 @@ dependencies = [
 ]
 
 [[package]]
+name = "sharded-slab"
+version = "0.1.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f40ca3c46823713e0d4209592e8d6e826aa57e928f09752619fc696c499637f6"
+dependencies = [
+ "lazy_static",
+]
+
+[[package]]
 name = "shell-words"
 version = "1.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1880,6 +1918,15 @@ dependencies = [
 ]
 
 [[package]]
+name = "thread_local"
+version = "1.1.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f60246a4944f24f6e018aa17cdeffb7818b76356965d03b07d6a9886e8962185"
+dependencies = [
+ "cfg-if",
+]
+
+[[package]]
 name = "tinystr"
 version = "0.8.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -2007,16 +2054,58 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "63e71662fa4b2a2c3a26f570f037eb95bb1f85397f3cd8076caed2f026a6d100"
 dependencies = [
  "pin-project-lite",
+ "tracing-attributes",
  "tracing-core",
 ]
 
 [[package]]
+name = "tracing-attributes"
+version = "0.1.31"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7490cfa5ec963746568740651ac6781f701c9c5ea257c58e057f3ba8cf69e8da"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
 name = "tracing-core"
 version = "0.1.36"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "db97caf9d906fbde555dd62fa95ddba9eecfd14cb388e4f491a66d74cd5fb79a"
 dependencies = [
  "once_cell",
+ "valuable",
+]
+
+[[package]]
+name = "tracing-log"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ee855f1f400bd0e5c02d150ae5de3840039a3f54b025156404e34c23c03f47c3"
+dependencies = [
+ "log",
+ "once_cell",
+ "tracing-core",
+]
+
+[[package]]
+name = "tracing-subscriber"
+version = "0.3.22"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2f30143827ddab0d256fd843b7a66d164e9f271cfa0dde49142c5ca0ca291f1e"
+dependencies = [
+ "matchers",
+ "nu-ansi-term",
+ "once_cell",
+ "regex-automata",
+ "sharded-slab",
+ "smallvec",
+ "thread_local",
+ "tracing",
+ "tracing-core",
+ "tracing-log",
 ]
 
 [[package]]
@@ -2074,6 +2163,12 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "06abde3611657adf66d383f00b093d7faecc7fa57071cce2578660c9f1010821"
 
 [[package]]
+name = "valuable"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ba73ea9cf16a25df0c8caa16c51acb937d5712a8429db78a3ee29d5dcacd3a65"
+
+[[package]]
 name = "version-ranges"
 version = "0.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"