diff --git a/Cargo.lock b/Cargo.lock
index 771f74b..51a9d5e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -13,9 +13,9 @@ dependencies = [
 
 [[package]]
 name = "allocator-api2"
-version = "0.2.20"
+version = "0.2.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "45862d1c77f2228b9e10bc609d5bc203d86ebc9b87ad8d5d5167a6c9abf739d9"
+checksum = "683d7910e743518b0e34f1186f92494becacb047c7b6bf616c96772180fef923"
 
 [[package]]
 name = "anes"
@@ -29,12 +29,24 @@ version = "1.0.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "55cc3b69f167a1ef2e161439aa98aed94e6028e5f9a59be9a6ffb47aef1651f9"
 
+[[package]]
+name = "anyhow"
+version = "1.0.95"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34ac096ce696dc2fcabef30516bb13c0a68a11d30131d3df6f04711467681b04"
+
 [[package]]
 name = "autocfg"
 version = "1.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ace50bade8e6234aa140d9a2f552bbee1db4d353f69b8217bc503490fc1a9f26"
 
+[[package]]
+name = "base16ct"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4c7f02d4ea65f2c1853089ffd8d2787bdbc63de2f0d29dedbcf8ccdfa0ccd4cf"
+
 [[package]]
 name = "basic-toml"
 version = "0.1.9"
@@ -97,18 +109,18 @@ dependencies = [
 
 [[package]]
 name = "clap"
-version = "4.5.21"
+version = "4.5.23"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fb3b4b9e5a7c7514dfa52869339ee98b3156b0bfb4e8a77c4ff4babb64b1604f"
+checksum = "3135e7ec2ef7b10c6ed8950f0f792ed96ee093fa088608f1c76e569722700c84"
 dependencies = [
  "clap_builder",
 ]
 
 [[package]]
 name = "clap_builder"
-version = "4.5.21"
+version = "4.5.23"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b17a95aa67cc7b5ebd32aa5370189aa0d79069ef1c64ce893bd30fb24bff20ec"
+checksum = "30582fc632330df2bd26877bde0c1f4470d57c582bbc070376afcd04d8cb4838"
 dependencies = [
  "anstyle",
  "clap_lex",
@@ -116,9 +128,9 @@ dependencies = [
 
 [[package]]
 name = "clap_lex"
-version = "0.7.3"
+version = "0.7.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "afb84c814227b90d6895e01398aee0d8033c00e7466aca416fb6a8e0eb19d8a7"
+checksum = "f46ad14479a25103f283c0f10005961cf086d8dc42205bb44c46ac563475dca6"
 
 [[package]]
 name = "codspeed"
@@ -144,12 +156,12 @@ dependencies = [
 
 [[package]]
 name = "colored"
-version = "2.1.0"
+version = "2.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cbf2150cce219b664a8a70df7a1f933836724b503f8a413af9365b4dcc4d90b8"
+checksum = "117725a109d387c937a1533ce01b450cbde6b88abceea8473c4d7a85853cda3c"
 dependencies = [
  "lazy_static",
- "windows-sys 0.48.0",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]
@@ -190,9 +202,9 @@ dependencies = [
 
 [[package]]
 name = "crossbeam-deque"
-version = "0.8.5"
+version = "0.8.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "613f8cc01fe9cf1a3eb3d7f488fd2fa8388403e97039e2f73692932e291a770d"
+checksum = "9dd111b7b7f7d55b72c0a6ae361660ee5853c9af73f70c3c2ef6858b950e2e51"
 dependencies = [
  "crossbeam-epoch",
  "crossbeam-utils",
@@ -209,9 +221,9 @@ dependencies = [
 
 [[package]]
 name = "crossbeam-utils"
-version = "0.8.20"
+version = "0.8.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "22ec99545bb0ed0ea7bb9b8e1e9122ea386ff8a48c0922e43f36d45ab09e0e80"
+checksum = "d0a5c400df2834b80a4c3327b3aad3a4c4cd4de0629063962b03235697506a28"
 
 [[package]]
 name = "crunchy"
@@ -233,9 +245,9 @@ checksum = "5443807d6dff69373d433ab9ef5378ad8df50ca6298caf15de6e52e24aaf54d5"
 
 [[package]]
 name = "foldhash"
-version = "0.1.3"
+version = "0.1.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f81ec6369c545a7d40e4589b5597581fa1c441fe1cce96dd1de43159910a36a2"
+checksum = "a0d2fde1f7b3d48b8395d5f2de76c18a528bd6a9cdde438df747bfcba3e05d6f"
 
 [[package]]
 name = "getrandom"
@@ -334,10 +346,11 @@ checksum = "d75a2a4b1b190afb6f5425f10f6a8f959d2ea0b9c2b1d79553551850539e4674"
 
 [[package]]
 name = "js-sys"
-version = "0.3.72"
+version = "0.3.76"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6a88f1bda2bd75b0452a14784937d796722fdebfe50df998aeb3f0b7603019a9"
+checksum = "6717b6b5b077764fb5966237269cb3c64edddde4b14ce42647430a78ced9e7b7"
 dependencies = [
+ "once_cell",
  "wasm-bindgen",
 ]
 
@@ -503,6 +516,7 @@ version = "0.23.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e484fd2c8b4cb67ab05a318f1fd6fa8f199fcc30819f08f07d200809dba26c15"
 dependencies = [
+ "anyhow",
  "cfg-if",
  "indoc",
  "libc",
@@ -753,9 +767,9 @@ dependencies = [
 
 [[package]]
 name = "smallvec"
-version = "2.0.0-alpha.7"
+version = "2.0.0-alpha.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e6a96cb564e12be8458b004bd829787ebe887de197d94516d2ba5a2a32235a0c"
+checksum = "5e22442b16a0c1bfae679ffed8ec5e160ae2aa8495cea891f0d2ff7b84fe5c4c"
 
 [[package]]
 name = "syn"
@@ -778,6 +792,8 @@ checksum = "61c41af27dd6d1e27b1b16b489db798443478cef1f06a660c96db617ba5de3b1"
 name = "test_results_parser"
 version = "0.5.1"
 dependencies = [
+ "anyhow",
+ "base16ct",
  "codspeed-criterion-compat",
  "indexmap",
  "pyo3",
@@ -794,18 +810,18 @@ dependencies = [
 
 [[package]]
 name = "thiserror"
-version = "2.0.3"
+version = "2.0.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c006c85c7651b3cf2ada4584faa36773bd07bac24acfb39f3c431b36d7e667aa"
+checksum = "f072643fd0190df67a8bab670c20ef5d8737177d6ac6b2e9a236cb096206b2cc"
 dependencies = [
  "thiserror-impl",
 ]
 
 [[package]]
 name = "thiserror-impl"
-version = "2.0.3"
+version = "2.0.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f077553d607adc1caf65430528a576c757a71ed73944b66ebb58ef2bbd243568"
+checksum = "7b50fa271071aae2e6ee85f842e2e28ba8cd2c5fb67f11fcb1fd70b276f9e7d4"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -858,9 +874,9 @@ checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
 
 [[package]]
 name = "wasm-bindgen"
-version = "0.2.95"
+version = "0.2.99"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "128d1e363af62632b8eb57219c8fd7877144af57558fb2ef0368d0087bddeb2e"
+checksum = "a474f6281d1d70c17ae7aa6a613c87fce69a127e2624002df63dcb39d6cf6396"
 dependencies = [
  "cfg-if",
  "once_cell",
@@ -869,13 +885,12 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen-backend"
-version = "0.2.95"
+version = "0.2.99"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cb6dd4d3ca0ddffd1dd1c9c04f94b868c37ff5fac97c30b97cff2d74fce3a358"
+checksum = "5f89bb38646b4f81674e8f5c3fb81b562be1fd936d84320f3264486418519c79"
 dependencies = [
  "bumpalo",
  "log",
- "once_cell",
  "proc-macro2",
  "quote",
  "syn",
@@ -884,9 +899,9 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen-macro"
-version = "0.2.95"
+version = "0.2.99"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e79384be7f8f5a9dd5d7167216f022090cf1f9ec128e6e6a482a2cb5c5422c56"
+checksum = "2cc6181fd9a7492eef6fef1f33961e3695e4579b9872a6f7c83aee556666d4fe"
 dependencies = [
  "quote",
  "wasm-bindgen-macro-support",
@@ -894,9 +909,9 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen-macro-support"
-version = "0.2.95"
+version = "0.2.99"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "26c6ab57572f7a24a4985830b120de1594465e5d500f24afe89e16b4e833ef68"
+checksum = "30d7a95b763d3c45903ed6c81f156801839e5ee968bb07e534c44df0fcd330c2"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -907,14 +922,14 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen-shared"
-version = "0.2.95"
+version = "0.2.99"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "65fc09f10666a9f147042251e0dda9c18f166ff7de300607007e96bdebc1068d"
+checksum = "943aab3fdaaa029a6e0271b35ea10b72b943135afe9bffca82384098ad0e06a6"
 
 [[package]]
 name = "watto"
 version = "0.2.0"
-source = "git+https://github.com/getsentry/watto#00977067f95c95ea317474d7fbfcd144deeb22a1"
+source = "git+https://github.com/getsentry/watto#5ce326705ce5452449651b5b3e2070aedd30850a"
 dependencies = [
  "hashbrown",
  "leb128",
@@ -923,9 +938,9 @@ dependencies = [
 
 [[package]]
 name = "web-sys"
-version = "0.3.72"
+version = "0.3.76"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f6488b90108c040df0fe62fa815cbdee25124641df01814dd7282749234c6112"
+checksum = "04dd7223427d52553d3702c004d3b2fe07c148165faa56313cb00211e31c12bc"
 dependencies = [
  "js-sys",
  "wasm-bindgen",
@@ -940,22 +955,13 @@ dependencies = [
  "windows-sys 0.59.0",
 ]
 
-[[package]]
-name = "windows-sys"
-version = "0.48.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "677d2418bec65e3338edb076e806bc1ec15693c5d0104683f2efe857f61056a9"
-dependencies = [
- "windows-targets 0.48.5",
-]
-
 [[package]]
 name = "windows-sys"
 version = "0.52.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "282be5f36a8ce781fad8c8ae18fa3f9beff57ec1b52cb3de0789201425d9a33d"
 dependencies = [
- "windows-targets 0.52.6",
+ "windows-targets",
 ]
 
 [[package]]
@@ -964,22 +970,7 @@ version = "0.59.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1e38bc4d79ed67fd075bcc251a1c39b32a1776bbe92e5bef1f0bf1f8c531853b"
 dependencies = [
- "windows-targets 0.52.6",
-]
-
-[[package]]
-name = "windows-targets"
-version = "0.48.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9a2fa6e2155d7247be68c096456083145c183cbbbc2764150dda45a87197940c"
-dependencies = [
- "windows_aarch64_gnullvm 0.48.5",
- "windows_aarch64_msvc 0.48.5",
- "windows_i686_gnu 0.48.5",
- "windows_i686_msvc 0.48.5",
- "windows_x86_64_gnu 0.48.5",
- "windows_x86_64_gnullvm 0.48.5",
- "windows_x86_64_msvc 0.48.5",
+ "windows-targets",
 ]
 
 [[package]]
@@ -988,46 +979,28 @@ version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9b724f72796e036ab90c1021d4780d4d3d648aca59e491e6b98e725b84e99973"
 dependencies = [
- "windows_aarch64_gnullvm 0.52.6",
- "windows_aarch64_msvc 0.52.6",
- "windows_i686_gnu 0.52.6",
+ "windows_aarch64_gnullvm",
+ "windows_aarch64_msvc",
+ "windows_i686_gnu",
  "windows_i686_gnullvm",
- "windows_i686_msvc 0.52.6",
- "windows_x86_64_gnu 0.52.6",
- "windows_x86_64_gnullvm 0.52.6",
- "windows_x86_64_msvc 0.52.6",
+ "windows_i686_msvc",
+ "windows_x86_64_gnu",
+ "windows_x86_64_gnullvm",
+ "windows_x86_64_msvc",
 ]
 
-[[package]]
-name = "windows_aarch64_gnullvm"
-version = "0.48.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2b38e32f0abccf9987a4e3079dfb67dcd799fb61361e53e2882c3cbaf0d905d8"
-
 [[package]]
 name = "windows_aarch64_gnullvm"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "32a4622180e7a0ec044bb555404c800bc9fd9ec262ec147edd5989ccd0c02cd3"
 
-[[package]]
-name = "windows_aarch64_msvc"
-version = "0.48.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dc35310971f3b2dbbf3f0690a219f40e2d9afcf64f9ab7cc1be722937c26b4bc"
-
 [[package]]
 name = "windows_aarch64_msvc"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "09ec2a7bb152e2252b53fa7803150007879548bc709c039df7627cabbd05d469"
 
-[[package]]
-name = "windows_i686_gnu"
-version = "0.48.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a75915e7def60c94dcef72200b9a8e58e5091744960da64ec734a6c6e9b3743e"
-
 [[package]]
 name = "windows_i686_gnu"
 version = "0.52.6"
@@ -1040,48 +1013,24 @@ version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0eee52d38c090b3caa76c563b86c3a4bd71ef1a819287c19d586d7334ae8ed66"
 
-[[package]]
-name = "windows_i686_msvc"
-version = "0.48.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8f55c233f70c4b27f66c523580f78f1004e8b5a8b659e05a4eb49d4166cca406"
-
 [[package]]
 name = "windows_i686_msvc"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "240948bc05c5e7c6dabba28bf89d89ffce3e303022809e73deaefe4f6ec56c66"
 
-[[package]]
-name = "windows_x86_64_gnu"
-version = "0.48.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "53d40abd2583d23e4718fddf1ebec84dbff8381c07cae67ff7768bbf19c6718e"
-
 [[package]]
 name = "windows_x86_64_gnu"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "147a5c80aabfbf0c7d901cb5895d1de30ef2907eb21fbbab29ca94c5b08b1a78"
 
-[[package]]
-name = "windows_x86_64_gnullvm"
-version = "0.48.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0b7b52767868a23d5bab768e390dc5f5c55825b6d30b86c844ff2dc7414044cc"
-
 [[package]]
 name = "windows_x86_64_gnullvm"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "24d5b23dc417412679681396f2b49f3de8c1473deb516bd34410872eff51ed0d"
 
-[[package]]
-name = "windows_x86_64_msvc"
-version = "0.48.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ed94fce61571a4006852b7389a063ab983c02eb1bb37b47f8272ce92d06d9538"
-
 [[package]]
 name = "windows_x86_64_msvc"
 version = "0.52.6"
diff --git a/Cargo.toml b/Cargo.toml
index ffead2f..b83f359 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -8,8 +8,10 @@ name = "test_results_parser"
 crate-type = ["cdylib", "rlib"]
 
 [dependencies]
-pyo3 = { version = "0.23.3", features = ["abi3-py312"] }
+anyhow = "1.0.94"
+base16ct = { version = "0.2.0", features = ["std"] }
 indexmap = "2.6.0"
+pyo3 = { version = "0.23.3", features = ["abi3-py312", "anyhow"] }
 quick-xml = "0.37.1"
 regex = "1.11.1"
 rinja = "0.3.5"
diff --git a/src/binary/bindings.rs b/src/binary/bindings.rs
new file mode 100644
index 0000000..4dca908
--- /dev/null
+++ b/src/binary/bindings.rs
@@ -0,0 +1,84 @@
+use std::mem::transmute;
+
+use anyhow::Context;
+use pyo3::prelude::*;
+
+use crate::Testrun;
+
+use super::{TestAnalytics, TestAnalyticsWriter};
+
+#[pyclass]
+pub struct BinaryFormatWriter {
+    writer: TestAnalyticsWriter,
+}
+
+impl BinaryFormatWriter {
+    pub fn new() -> Self {
+        Self {
+            writer: TestAnalyticsWriter::new(60),
+        }
+    }
+    pub fn add_testruns(
+        &mut self,
+        timestamp: u32,
+        commit_hash: &str,
+        flags: &[&str],
+        testruns: &[Testrun],
+    ) -> anyhow::Result<()> {
+        let commit_hash_base16 = if commit_hash.len() > 40 {
+            commit_hash
+                .get(..40)
+                .context("expected a hex-encoded commit hash")?
+        } else {
+            commit_hash
+        };
+        let mut commit_hash = super::CommitHash::default();
+        base16ct::mixed::decode(commit_hash_base16, &mut commit_hash.0)?;
+
+        let mut session = self.writer.start_session(timestamp, commit_hash, flags);
+        for test in testruns {
+            session.insert(test);
+        }
+        Ok(())
+    }
+
+    pub fn serialize(self) -> anyhow::Result<Vec<u8>> {
+        let mut buffer = vec![];
+        self.writer.serialize(&mut buffer)?;
+        Ok(buffer)
+    }
+}
+
+#[pyclass]
+pub struct AggregationReader {
+    buffer: Vec<u8>,
+    format: TestAnalytics<'static>,
+}
+
+#[pyclass]
+pub struct TestAggregate {
+    // TODO
+}
+
+#[pymethods]
+impl AggregationReader {
+    #[new]
+    pub fn new(buffer: Vec<u8>, timestamp: u32) -> anyhow::Result<Self> {
+        let format = TestAnalytics::parse(&buffer, timestamp)?;
+        // SAFETY: the lifetime of `TestAnalytics` depends on `buffer`,
+        // which we do not mutate, and which outlives the parsed format.
+        let format = unsafe { transmute(format) };
+
+        Ok(Self { buffer, format })
+    }
+
+    #[pyo3(signature = (interval_start, interval_end, flag=None))]
+    pub fn get_test_aggregates(
+        &self,
+        interval_start: usize,
+        interval_end: usize,
+        flag: Option<&str>,
+    ) -> Vec<TestAggregate> {
+        vec![]
+    }
+}
diff --git a/src/binary/mod.rs b/src/binary/mod.rs
index bacb7d8..01ccb95 100644
--- a/src/binary/mod.rs
+++ b/src/binary/mod.rs
@@ -1,3 +1,4 @@
+mod bindings;
 mod commithashes_set;
 mod error;
 mod flags_set;
@@ -6,6 +7,7 @@ mod raw;
 mod timestamps;
 mod writer;
 
+pub use bindings::{AggregationReader, BinaryFormatWriter};
 pub use error::{TestAnalyticsError, TestAnalyticsErrorKind};
 pub use format::{Test, TestAnalytics};
 pub use raw::CommitHash;
diff --git a/src/testrun.rs b/src/testrun.rs
index be45698..a9a8f36 100644
--- a/src/testrun.rs
+++ b/src/testrun.rs
@@ -1,7 +1,7 @@
 use std::fmt::Display;
 
 use pyo3::class::basic::CompareOp;
-use pyo3::{prelude::*, pyclass};
+use pyo3::prelude::*;
 
 #[derive(Clone, Copy, Debug, PartialEq)]
 #[pyclass(eq, eq_int)]
@@ -75,12 +75,6 @@ pub fn check_testsuites_name(testsuites_name: &str) -> Option<Framework> {
         .next()
 }
 
-// testrun is unique on:
-// - testsuite
-// - classname
-// - name
-// the UI shows `computed_name`
-
 #[derive(Clone, Debug, PartialEq)]
 #[pyclass]
 pub struct Testrun {