feat: initial release — Honeycomb-style wide events for Rust

Amp-Thread-ID: https://ampcode.com/threads/T-019cbd63-d8c4-74a9-914a-549909f4e122
Co-authored-by: Amp <amp@ampcode.com>

Author: mikn

.githooks/pre-push

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+#!/usr/bin/env bash
+set -euo pipefail
+
+echo "pre-push: running checks..."
+cargo fmt --check
+cargo clippy --all-targets --all-features -- -D warnings
+cargo test --all-features
+RUSTDOCFLAGS="-D warnings" cargo doc --all-features --no-deps
+echo "pre-push: all checks passed."

.github/dependabot.yml

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+version: 2
+updates:
+  - package-ecosystem: cargo
+    directory: /
+    schedule:
+      interval: weekly
+  - package-ecosystem: github-actions
+    directory: /
+    schedule:
+      interval: weekly

.github/workflows/ci.yml

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+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  test:
+    name: Test (${{ matrix.toolchain }}, ${{ matrix.features }})
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        toolchain: [stable, nightly]
+        features:
+          - ""
+          - --features tokio
+          - --features opentelemetry
+          - --all-features
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@master
+        with:
+          toolchain: ${{ matrix.toolchain }}
+      - run: cargo test ${{ matrix.features }}
+
+  clippy:
+    name: Clippy
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: clippy
+      - run: cargo clippy --all-targets --all-features -- -D warnings
+
+  fmt:
+    name: Format
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: rustfmt
+      - run: cargo fmt --check
+
+  doc:
+    name: Documentation
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+      - run: cargo doc --all-features --no-deps
+        env:
+          RUSTDOCFLAGS: -D warnings

.github/workflows/release.yml

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+name: Release
+
+on:
+  push:
+    tags:
+      - "v*"
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  publish:
+    name: Publish to crates.io
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+      - run: cargo publish
+        env:
+          CARGO_REGISTRY_TOKEN: ${{ secrets.CARGO_REGISTRY_TOKEN }}

.gitignore

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+/target
+Cargo.lock

Cargo.toml

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+[package]
+name = "wide-event"
+version = "0.1.0"
+edition = "2021"
+description = "Honeycomb-style wide events — accumulate structured fields throughout a request lifecycle and emit as a single JSON line via tracing"
+license = "MIT"
+repository = "https://github.com/lovablelabs/wide-event"
+keywords = ["tracing", "observability", "wide-event", "structured-logging", "honeycomb"]
+categories = ["development-tools::debugging", "development-tools::profiling"]
+
+[features]
+default = []
+opentelemetry = ["dep:opentelemetry", "dep:tracing-opentelemetry"]
+tokio = ["dep:tokio"]
+
+[dependencies]
+serde = { version = "1.0", features = ["derive"] }
+serde_json = "1.0"
+tracing = "0.1"
+tracing-subscriber = { version = "0.3", default-features = false, features = ["registry", "fmt"] }
+
+opentelemetry = { version = "0.31", default-features = false, features = ["trace"], optional = true }
+tracing-opentelemetry = { version = "0.32", optional = true }
+tokio = { version = "1", features = ["rt"], optional = true }
+
+[dev-dependencies]
+criterion = { version = "0.5", features = ["html_reports"] }
+tracing-subscriber = { version = "0.3", features = ["registry", "fmt", "env-filter"] }
+tokio = { version = "1", features = ["rt", "macros"] }
+
+[[bench]]
+name = "wide_event"
+harness = false

LICENSE-MIT

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+MIT License
+
+Copyright (c) 2025 Lovable
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# wide-event
+
+[![Crates.io](https://img.shields.io/crates/v/wide-event.svg)](https://crates.io/crates/wide-event)
+[![docs.rs](https://docs.rs/wide-event/badge.svg)](https://docs.rs/wide-event)
+[![License: MIT](https://img.shields.io/badge/license-MIT-blue.svg)](LICENSE-MIT)
+
+Honeycomb-style wide events for Rust.
+
+A wide event accumulates key-value pairs throughout a request (or task)
+lifecycle and emits them as a **single structured event** when the request
+completes. This gives you one row per request in your log aggregator with
+every dimension attached — perfect for high-cardinality exploratory analysis.
+
+## Quick start
+
+```rust
+use wide_event::{WideEventGuard, WideEventLayer};
+use tracing_subscriber::prelude::*;
+
+// Once at startup:
+tracing_subscriber::registry()
+    .with(WideEventLayer::stdout().with_system("myapp"))
+    .init();
+
+// Per request — guard auto-emits on drop:
+{
+    let req = WideEventGuard::new("http");
+    req.set_str("method", "GET");
+    req.set_str("path", "/api/users");
+    req.set_u64("status", 200);
+} // ← emitted here as single JSON line
+```
+
+## How it works
+
+1. `WideEvent::new` starts a timer and creates an empty field map.
+2. Throughout processing, call setters (`set_str`, `set_u64`, `incr`, etc.)
+   to accumulate fields — these are cheap local `Mutex` operations that never
+   touch the tracing subscriber.
+3. `WideEvent::emit` (or `WideEventGuard` drop) finalizes the record, pushes
+   it to a thread-local stack, and dispatches a structured `tracing::info!`
+   event. The `WideEventLayer` pulls the record from the stack, formats the
+   timestamp, and serializes in a single pass.
+
+## Features
+
+| Feature | Description |
+|---------|-------------|
+| `opentelemetry` | Attaches `trace_id` and `span_id` from the current OpenTelemetry span context |
+| `tokio` | Provides `context::scope` and `context::current` for async task-local wide event propagation |
+
+```toml
+[dependencies]
+wide-event = { version = "0.1", features = ["tokio"] }
+```
+
+## Formatter options
+
+- **`JsonFormatter`** (default) — one JSON object per line
+- **`LogfmtFormatter`** — `key=value` pairs per line
+
+```rust
+use wide_event::{WideEventLayer, LogfmtFormatter};
+
+let layer = WideEventLayer::new(std::io::stdout(), LogfmtFormatter);
+```
+
+## Performance
+
+- Field keys are `&'static str` — zero allocation on every setter call. Field
+  names are almost always string literals, so this is natural and avoids the
+  `key.to_string()` overhead entirely.
+- Field setters (`set_str`, `set_u64`, `incr`, …) are cheap local `Mutex`
+  operations — they never interact with the tracing subscriber.
+- Timestamp formatting reuses a thread-local buffer — no `String` allocation
+  per emit.
+- Serialization happens once at emit time in a single pass over the accumulated
+  fields.
+- A thread-local emit stack avoids cross-thread synchronization on the hot path.
+
+## Development
+
+```bash
+# Set up pre-push hook (runs fmt, clippy, tests before each push)
+git config core.hooksPath .githooks
+
+# Release a new version (bumps Cargo.toml, commits, tags, pushes)
+# CI publishes to crates.io automatically on tag push.
+cargo release patch  # or: minor, major
+```
+
+Requires [`cargo-release`](https://crates.io/crates/cargo-release):
+`cargo install cargo-release`
+
+## License
+
+MIT — see [LICENSE-MIT](LICENSE-MIT).