<!DOCTYPE html><html lang="en"><head><meta http-equiv="Content-Type" content="text/html charset=UTF-8"><meta charset="UTF-8"><meta name="viewport" content="width=device-width"><meta name="x-apple-disable-message-reformatting"><title>TLDR Dev</title><meta name="color-scheme" content="light dark"><meta name="supported-color-schemes" content="light dark"><style type="text/css">
:root {
color-scheme: light dark; supported-color-schemes: light dark;
}
*,
*:after,
*:before {
-webkit-box-sizing: border-box; -moz-box-sizing: border-box; box-sizing: border-box;
}
* {
-ms-text-size-adjust: 100%; -webkit-text-size-adjust: 100%;
}
html,
body,
.document {
width: 100% !important; height: 100% !important; margin: 0; padding: 0;
}
body {
-webkit-font-smoothing: antialiased; -moz-osx-font-smoothing: grayscale; text-rendering: optimizeLegibility;
}
div[style*="margin: 16px 0"] {
margin: 0 !important;
}
table,
td {
mso-table-lspace: 0pt; mso-table-rspace: 0pt;
}
table {
border-spacing: 0; border-collapse: collapse; table-layout: fixed; margin: 0 auto;
}
img {
-ms-interpolation-mode: bicubic; max-width: 100%; border: 0;
}
*[x-apple-data-detectors] {
color: inherit !important; text-decoration: none !important;
}
.x-gmail-data-detectors,
.x-gmail-data-detectors *,
.aBn {
border-bottom: 0 !important; cursor: default !important;
}
.btn {
-webkit-transition: all 200ms ease; transition: all 200ms ease;
}
.btn:hover {
background-color: #f67575; border-color: #f67575;
}
* {
font-family: Arial, Helvetica, sans-serif; font-size: 18px;
}
@media screen and (max-width: 600px) {
.container {
width: 100%; margin: auto;
}
.stack {
display: block!important; width: 100%!important; max-width: 100%!important;
}
.btn {
display: block; width: 100%; text-align: center;
}
}
body,
p,
td,
tr,
.body,
table,
h1,
h2,
h3,
h4,
h5,
h6,
div,
span {
background-color: #FEFEFE !important; color: #010101 !important;
}
@media (prefers-color-scheme: dark) {
body,
p,
td,
tr,
.body,
table,
h1,
h2,
h3,
h4,
h5,
h6,
div,
span {
background-color: #27292D !important; color: #FEFEFE !important;
}
}
a {
color: inherit !important; text-decoration: underline !important;
}
</style><!--[if mso | ie]>
<style type="text/css">
a {
background-color: #FEFEFE !important; color: #010101 !important;
}
@media (prefers-color-scheme: dark) {
a {
background-color: #27292D !important; color: #FEFEFE !important;
}
}
</style>
<![endif]--></head><body class="">
<div style="display: none; max-height: 0px; overflow: hidden;">Hermes coordinated 1,393 subagents over about 19 active hours to refactor a million-line Python repository, cutting non-test source by 34.4% β β β β β β β β β β β β β β β β β β β β β β β β β β β β β β β β β β β β β β β β β β β β β β β β β β β β </div>
<div style="display: none; max-height: 0px; overflow: hidden;">
<br>
</div>
<table align="center" class="document"><tbody><tr><td valign="top">
<table align="center" border="0" cellpadding="0" cellspacing="0" class="container" width="600"><tbody><tr class="inner-body"><td>
<table align="center" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr class="header"><td bgcolor="" class="container">
<table width="100%"><tbody><tr><td class="container">
<table align="center" bgcolor="" border="0" cellpadding="0" cellspacing="0" style="margin-top: 0px;" width="100%"><tbody><tr><td style="padding: 0px;">
<table align="center" bgcolor="" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td class="container" style="padding: 15px 15px;">
<div style="text-align: center;">
<span style="margin-right: 0px;"><a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Ftldr.tech%2Fdev%3Futm_source=tldrdev/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/COVPyuRm-IpOZXRDiKL8H5IgiEHtGWrvMktm_zkV-qg=452" rel="noopener noreferrer" target="_blank"><span>Sign Up</span></a>
|<span style="margin-right: 2px; margin-left: 2px;"><a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fadvertise.tldr.tech%2F%3Futm_source=tldrdev%26utm_medium=newsletter%26utm_campaign=advertisetopnav/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/KHfGAsgBlLCCjHYJVLFrvFh1L5cucEkd8-tc57K1uoo=452" rel="noopener noreferrer" target="_blank"><span>Advertise</span></a></span>|<span style="margin-left: 2px;"><a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fa.tldrnewsletter.com%2Fweb-version%3Fep=1%26lc=156b9020-84b7-11f0-a976-55fc1d40139c%26p=ba727210-b273-11f1-abe7-313a83b4597c%26pt=campaign%26t=1789643641%26s=11cfda5d8025fdd1540b804abf30ff0a1e106f3dda66cf67765e98d77b515993/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/WgjLmKO6jaFpd6-jH3c62DJatqa3clZ8OdIrfjzZyT8=452"><span>View Online</span></a></span>
<br>
</span></div>
</td></tr></tbody></table>
<table align="center" bgcolor="" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td class="container" style="text-align: center;"><span data-darkreader-inline-color="" style="--darkreader-inline-color:#3db3ff; color: rgb(51, 175, 255) !important; font-size: 30px;">T</span><span style="font-size: 30px;"><span data-darkreader-inline-color="" style="color: rgb(232, 192, 96) !important; --darkreader-inline-color:#e8c163; font-size:30px;">L</span><span data-darkreader-inline-color="" style="color: rgb(101, 195, 173) !important; --darkreader-inline-color:#6ec7b2; font-size:30px;">D</span></span><span data-darkreader-inline-color="" style="--darkreader-inline-color:#dd6e6e; color: rgb(220, 107, 107) !important; font-size: 30px;">R</span>
<br>
</td></tr></tbody></table>
<br>
<table align="center" bgcolor="" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr id="together-with"><td align="center" height="20" style="vertical-align:middle !important;" valign="middle" width="100%"><strong style="vertical-align:middle !important; height: 100%;">Together With </strong>
<a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fworkos.com%2Finit%3Futm_source=tldrfounders%26utm_medium=newsletter%26utm_campaign=q32026/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/0-jWkI0gwcYQaWfexL7SLRbMKuIFoQd0L0SGmrRwj6g=452"><img src="https://images.tldr.tech/workos50.png" valign="middle" style="vertical-align: middle !important; height: 100%;" alt="WorkOS"></a></td></tr></tbody></table>
<table style="table-layout: fixed; width:100%;" width="100%"><tbody><tr><td style="padding:0;border-collapse:collapse;border-spacing:0;margin:0;">
<div style="text-align: center;">
<h1><strong> TLDR Dev <span id="date">2026-09-17</span></strong></h1>
</div>
</td></tr></tbody></table>
<table style="table-layout: fixed; width:100%;" width="100%"><tbody><tr id="sponsy-copy"><td class="container" style="padding: 15px 15px;">
<div class="text-block">
<span>
<a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fworkos.com%2Finit%3Futm_source=tldrfounders%26utm_medium=newsletter%26utm_campaign=q32026/2/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/UH36cSWF-NMv6uTlDwu7uaB-sLAiWl854gPi9JKjY5A=452">
<span>
<strong>If you're building with AI, clear your schedule for October 7 (Sponsor)</strong>
</span>
</a>
<br>
<br>
<span style="font-family: "Helvetica Neue", Helvetica, Arial, Verdana, sans-serif;">
<a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fworkos.com%2F%3Futm_source=tldrfounders%26utm_medium=newsletter%26utm_campaign=q32026/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/7ngrmAYiTP4_QL5OmUhPKI7yH-Ecmn-VLHym78J_1GU=452" rel="noopener noreferrer" target="_blank"><span>WorkOS</span></a> is hosting <a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fworkos.com%2Finit%3Futm_source=tldrfounders%26utm_medium=newsletter%26utm_campaign=q32026/3/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/BjfftN5tCYq2jkVUdti7O1SiqPrOZjMn3ogPx5IsUEw=452" rel="noopener noreferrer" target="_blank"><span>init()</span></a>, a one-day conference for people building with AI. October 7 at SFJAZZ Center in San Francisco, during SF Tech Week.
<br>
<br>Aaron Levie (Box), Howie Liu (Hyperagent), swyx, Rita Kozlov (Cloudflare), Claire Vo, Evan Conrad (SF Compute), and more on the decisions, tradeoffs, and lessons behind the AI products they're shipping today.
<br>
<br>Join the people building what's next.
<br>
<br><a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fluma.com%2Finit-conf%3Fcoupon=TLDR-DEV/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/tnmVLL6LJQ4rZQ7Pyg1FvZzvvVhh94WNmswNMwfs3D4=452" rel="noopener noreferrer" target="_blank"><span><strong>Register for init() β</strong></span></a>
</span>
</span>
</div>
</td></tr></tbody></table>
</td></tr></tbody></table>
</td></tr></tbody></table>
</td></tr>
<tr bgcolor=""><td class="container">
<table align="center" bgcolor="" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td style="padding: 0px;">
<table align="center" bgcolor="" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td class="container" style="padding-top: 0px; padding-bottom: 0px;">
<div class="text-block">
<div style="text-align: center;"><span style="font-size: 36px;">π§βπ»</span></div>
</div>
</td></tr></tbody></table>
<table align="center" bgcolor="" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td class="container" style="padding-top: 0px; padding-bottom: 0px;">
<div class="text-block">
<div style="text-align: center;">
<h1><strong>Articles & Tutorials</strong></h1>
</div>
</div>
</td></tr></tbody></table>
<table style="table-layout: fixed; width: 100%;" width="100%"><tbody><tr><td style="padding:0;border-collapse:collapse;border-spacing:0;margin:0;" valign="top">
<table align="center" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td class="container" style="padding: 15px 15px;">
<div class="text-block">
<span>
<a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fnousresearch.com%2Frefactoring-hermes-with-1393-agents%3Futm_source=tldrdev/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/SqNpIu47uLllSK6VZ8TMrN3AMBYyh4AR6mTVOFFIATg=452">
<span>
<strong>Refactoring Hermes with 1,393 agents (10 minute read)</strong>
</span>
</a>
<br>
<br>
<span style="font-family: "Helvetica Neue", Helvetica, Arial, Verdana, sans-serif;">
Hermes coordinated 1,393 subagents over about 19 active hours to refactor a million-line Python repository, cutting non-test source by 34.4% for roughly $19,300 in model costs. Worktrees and frozen baselines supported parallel integration, but community review still caught removed public APIs and changed exception handling that the tests missed.
</span>
</span>
</div>
</td></tr></tbody></table>
<table align="center" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td class="container" style="padding: 15px 15px;">
<div class="text-block">
<span>
<a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fsurgehq.ai%2Flearn%2Fevaluations%3Futm_source=tldrdev/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/9d6N-vdYzR5lAP0XaZ_5aw5bPjNLQzKq84tG26xGwro=452">
<span>
<strong>Designing Evaluations That Actually Tell You Something (25 minute read)</strong>
</span>
</a>
<br>
<br>
<span style="font-family: "Helvetica Neue", Helvetica, Arial, Verdana, sans-serif;">
Useful evaluations begin with a decision and a representative set of real workflows, including rare high-risk, edge, and adversarial cases. This guide covers dataset structure, evaluator calibration, inter-rater agreement, failure severity, production-derived tests, and hidden holdouts that reduce overfitting to a fixed score.
</span>
</span>
</div>
</td></tr></tbody></table>
</td></tr></tbody></table>
<table align="center" bgcolor="" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td class="container" style="padding-top: 0px; padding-bottom: 0px;">
<div class="text-block">
<div style="text-align: center;"><span style="font-size: 36px;">π§ </span></div>
</div>
</td></tr></tbody></table>
<table align="center" bgcolor="" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td class="container" style="padding-top: 0px; padding-bottom: 0px;">
<div class="text-block">
<div style="text-align: center;">
<h1><strong>Opinions & Advice</strong></h1>
</div>
</div>
</td></tr></tbody></table>
<table style="table-layout: fixed; width: 100%;" width="100%"><tbody><tr><td style="padding:0;border-collapse:collapse;border-spacing:0;margin:0;" valign="top">
<table align="center" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td class="container" style="padding: 15px 15px;">
<div class="text-block">
<span>
<a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fposthog.com%2Fblog%2Fself-driving-loops%3Futm_source=tldrdev/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/8TNRZkynsPuGyKJkBGz1JucK77vJbQ1gNlo7sQj3og4=452">
<span>
<strong>6-7 loops we use everyday to make PostHog self-driving (14 minute read)</strong>
</span>
</a>
<br>
<br>
<span style="font-family: "Helvetica Neue", Helvetica, Arial, Verdana, sans-serif;">
PostHog describes agent loops that turn MCP feedback, Slack reports, issue specs, anomaly alerts, session replays, and runtime logs into investigations and pull requests. The key is persistent validation: scouts deduplicate evidence, keep humans at review and merge gates, then return after deployment to confirm the fix actually held.
</span>
</span>
</div>
</td></tr></tbody></table>
<table align="center" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td class="container" style="padding: 15px 15px;">
<div class="text-block">
<span>
<a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fbharatsharma.pro%2Farticles%2Factivity-based-engineering-metrics-are-obsolete%3Futm_source=tldrdev/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/0SPVZCFKtce-H94xlZqUWxTDVaVVvvS56TADqa7QTZw=452">
<span>
<strong>AI Is Making Activity-Based Engineering Metrics Obsolete (8 minute read)</strong>
</span>
</a>
<br>
<br>
<span style="font-family: "Helvetica Neue", Helvetica, Arial, Verdana, sans-serif;">
AI-generated code makes lines of code, commit counts, and raw pull request volume even weaker proxies for engineering value. The proposed replacement keeps delivery outcomes and adds team-level diagnostics such as review queue time, 14-day rework, validation failures, remediation deployments, and rework per unit of AI spend, while keeping them out of individual performance reviews.
</span>
</span>
</div>
</td></tr></tbody></table>
</td></tr></tbody></table>
<table align="center" bgcolor="" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td class="container" style="padding-top: 0px; padding-bottom: 0px;">
<div class="text-block">
<div style="text-align: center;"><span style="font-size: 36px;">π</span></div></div>
</td></tr></tbody></table>
<table align="center" bgcolor="" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td class="container" style="padding-top: 0px; padding-bottom: 0px;">
<div class="text-block">
<div style="text-align: center;">
<h1><strong>Launches & Tools</strong></h1>
</div>
</div>
</td></tr></tbody></table>
<table style="table-layout: fixed; width: 100%;" width="100%"><tbody><tr><td style="padding:0;border-collapse:collapse;border-spacing:0;margin:0;" valign="top">
<table align="center" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td class="container" style="padding: 15px 15px;">
<div class="text-block">
<span>
<a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fclickhouse.com%2Fcloud%2Fpostgres%3Futm_source=tldr%26utm_medium=paid-newsletter%26utm_id=tldr2%26sp=sdbGjj1ov52sWVR46SE0WaP9/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/_mQw1LzNCdEVVMbmw5CvjpaQB1OvBE5gHjypEwvud7k=452">
<span>
<strong>Postgres for your app. ClickHouse for its analytics. (Sponsor)</strong>
</span>
</a>
<br>
<br>
<span style="font-family: "Helvetica Neue", Helvetica, Arial, Verdana, sans-serif;">
Run your app on ClickHouse Managed Postgres, with fast local NVMe storage and automatic backups. Replicate data into ClickHouse for analytics, all in one platform. Build with your own data and get $300 in free trial credits.<br><br><a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fconsole.clickhouse.cloud%2FsignUp%3Fintent=pg%26utm_source=tldr%26utm_medium=paid-newsletter%26utm_id=tldr2%26sp=sdbGjj1ov52sWVR46SE0WaP9/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/9_-ic4vPBX4ZQEWTRkHBDkW8Ik0ed8ZtwKnGuoT5pso=452" rel="noopener noreferrer nofollow" target="_blank"><span><strong>Start your free trial</strong></span></a>
</span>
</span>
</div>
</td></tr></tbody></table>
<table align="center" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td class="container" style="padding: 15px 15px;">
<div class="text-block">
<span>
<a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fgithub.com%2FQ00%2Fouroboros%3Futm_source=tldrdev/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/ofnCzJRw2y4ePLgzlbERzHxAtT8lZE5wDcTF8-9WFqs=452">
<span>
<strong>Ouroboros (GitHub Repo)</strong>
</span>
</a>
<br>
<br>
<span style="font-family: "Helvetica Neue", Helvetica, Arial, Verdana, sans-serif;">
Ouroboros is a local-first Agent OS that turns vague coding requests into replayable, policy-bound workflows through an interview, immutable specification, execution ledger, staged evaluation, and budgeted evolution loop. Its MCP server and adapters support 14 agent runtimes, including Claude Code, Codex CLI, Gemini CLI, OpenCode, and Copilot.
</span>
</span>
</div>
</td></tr></tbody></table>
<table align="center" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td class="container" style="padding: 15px 15px;">
<div class="text-block">
<span>
<a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fgithub.com%2FMakazhanAlpamys%2FSoup%3Futm_source=tldrdev/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/60cMIcd2YcBXKeJCPG0t4tMg-qtvybcGfoV0jT_FDqM=452">
<span>
<strong>Soup (GitHub Repo)</strong>
</span>
</a>
<br>
<br>
<span style="font-family: "Helvetica Neue", Helvetica, Arial, Verdana, sans-serif;">
Soup wraps LLM fine-tuning and post-training in one YAML file and command, with support for common training methods, local and cloud backends, evaluation, export, serving, and a web UI. Its beta layer-streaming mode trained an 8B NF4 LoRA model in 3.32 GB of GPU memory, though the published laptop throughput predates a later correctness repair.
</span>
</span>
</div>
</td></tr></tbody></table>
</td></tr></tbody></table>
<table align="center" bgcolor="" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td class="container" style="padding-top: 0px; padding-bottom: 0px;">
<div class="text-block">
<div style="text-align: center;"><span style="font-size: 36px;">π</span></div></div>
</td></tr></tbody></table>
<table align="center" bgcolor="" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td class="container" style="padding-top: 0px; padding-bottom: 0px;">
<div class="text-block">
<div style="text-align: center;"><strong><h1>Miscellaneous</h1></strong></div>
</div>
</td></tr></tbody></table>
<table bgcolor="" style="table-layout: fixed; width: 100%;" width="100%"><tbody><tr><td style="padding:0;border-collapse:collapse;border-spacing:0;margin:0;" valign="top">
<table align="center" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td class="container" style="padding: 15px 15px;">
<div class="text-block">
<span>
<a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Faccomplish.ai%2Fblog%2Fescaping-the-openai-codex-sandbox-twice%2F%3Futm_source=tldrdev/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/8UZ4P8LSxAZLYOot8yF4el53wBak68GRlr6QrCtnFPE=452">
<span>
<strong>Escaping the OpenAI Codex sandbox, twice (5 minute read)</strong>
</span>
</a>
<br>
<br>
<span style="font-family: "Helvetica Neue", Helvetica, Arial, Verdana, sans-serif;">
Two disclosed Codex sandbox escapes crossed different trust boundaries: one widened patch write permissions, while another recovered a trusted token from a shared JavaScript heap to reach an unsandboxed parent process. Both were fixed within eight days, and the broader lesson is to keep enforcement and real credentials outside the environment being constrained.
</span>
</span>
</div>
</td></tr></tbody></table>
<table align="center" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td class="container" style="padding: 15px 15px;">
<div class="text-block">
<span>
<a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fzartbot.github.io%2Fblog%2Fmodel_arch%2Fdsv41flash_arch%2Fen.html%3Futm_source=tldrdev/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/aZQezLm1M_k0uzE1LxGD8Cg6EKHvNFJMPy-Y0B6YZ_g=452">
<span>
<strong>DeepSeek-V4.1 Flash: Pushing the Limits of KV Cache Compression (146 minute read)</strong>
</span>
</a>
<br>
<br>
<span style="font-family: "Helvetica Neue", Helvetica, Arial, Verdana, sans-serif;">
This deep dive explains how DeepSeek-V4.1 Flash combines a causal encoder-decoder, cross-layer sparse attention and index reuse, hierarchical retrieval, Engram memory, and FP4 storage to shrink the KV cache to 890 bytes per token. The 40-layer design activates 8B parameters during prefill and 16B during decoding, targeting lower HBM, SSD, and compute costs for long-horizon agent workloads.
</span>
</span>
</div>
</td></tr></tbody></table>
</td></tr></tbody></table>
<table align="center" bgcolor="" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td class="container" style="padding-top: 0px; padding-bottom: 0px;">
<div class="text-block">
<div style="text-align: center;"><span style="font-size: 36px;">β‘</span></div></div>
</td></tr></tbody></table>
<table align="center" bgcolor="" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td class="container" style="padding-top: 0px; padding-bottom: 0px;">
<div class="text-block">
<div style="text-align: center;">
<h1><strong>Quick Links</strong></h1>
</div>
</div>
</td></tr></tbody></table>
<table bgcolor="" style="table-layout: fixed; width: 100%;" width="100%"><tbody><tr><td style="padding:0;border-collapse:collapse;border-spacing:0;margin:0;" valign="top">
<table align="center" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td class="container" style="padding: 15px 15px;">
<div class="text-block">
<span>
<a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fwww.agora.io%2Fen%2Fproducts%2Fconversational-ai-engine%2F%3Futm_source=TLDR%26utm_medium=Newsletter%26utm_campaign=ConvoAI-Sep-26%26sp=NQLwVGQ4h5PBxAizXpR3npvD/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/hXR3vFs_yOpf3kTkp5NhV71urQl7mPfKoFZBwXF381s=452">
<span>
<strong>Production-grade infrastructure for conversational AI (Sponsor)</strong>
</span>
</a>
<br>
<br>
<span style="font-family: "Helvetica Neue", Helvetica, Arial, Verdana, sans-serif;">
Build AI agents and voice-enabled applications that perform and scale even under challenging network conditionsβwith fully managed, real-time infrastructure. <a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fwww.agora.io%2Fen%2Fproducts%2Fconversational-ai-engine%2F%3Futm_source=TLDR%26utm_medium=Newsletter%26utm_campaign=ConvoAI-Sep-26%26sp=NQLwVGQ4h5PBxAizXpR3npvD/2/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/a3O5wMb7Q5TmLK9Qk6PYVik6gjsMuMfqpyiJKu5nX_M=452" rel="noopener noreferrer nofollow" target="_blank"><span>Get started with 300 free minutes</span></a>.
</span>
</span>
</div>
</td></tr></tbody></table>
<table align="center" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td class="container" style="padding: 15px 15px;">
<div class="text-block">
<span>
<a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fwww.vals.ai%2Fblogs%2Fcheating-on-the-rise%3Futm_source=tldrdev/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/NQ5Rj6M_A4uldDUGye4g0XR6doZ7LOXhcUJF2YEA29s=452">
<span>
<strong>AI Cheating is on the Rise (4 minute read)</strong>
</span>
</a>
<br>
<br>
<span style="font-family: "Helvetica Neue", Helvetica, Arial, Verdana, sans-serif;">
Trajectory audits across BioMysteryBench, Terminal-Bench 2.1, and SWE-bench Verified show rising attempts to obtain prohibited answers, strengthening the case for independent evaluators and explicit anti-cheating checks.
</span>
</span>
</div>
</td></tr></tbody></table>
<table align="center" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td class="container" style="padding: 15px 15px;">
<div class="text-block">
<span>
<a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fwill-keleher.com%2Fposts%2Fsmall-programming-tricks-matter%2F%3Futm_source=tldrdev/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/xgU20VugQvrTTRuWjdmvhBB59qfS7vj031p4R0uN0RU=452">
<span>
<strong>Small Programming Tricks (4 minute read)</strong>
</span>
</a>
<br>
<br>
<span style="font-family: "Helvetica Neue", Helvetica, Arial, Verdana, sans-serif;">
Small, reusable tricks such as fuzzy shell history, EXPLAIN ANALYZE, git log -S, and ripgrep can compound into meaningful productivity gains when teams share them regularly.
</span>
</span>
</div>
</td></tr></tbody></table>
<table align="center" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td class="container" style="padding: 15px 15px;">
<div class="text-block">
<span>
<a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fevanhahn.com%2Fposts%2F2026-09-13-programmers-dislike-reduce%2F%3Futm_source=tldrdev/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/tQd0c6ewT9NgBzlAkPGbu-qdHinEfuVDNadBvy-ji8U=452">
<span>
<strong>Anecdotally, programmers dislike "reduce" (2 minute read)</strong>
</span>
</a>
<br>
<br>
<span style="font-family: "Helvetica Neue", Helvetica, Arial, Verdana, sans-serif;">
Code reviews often accept map and filter while flagging βreduceβ as harder to read, possibly because it is less familiar, less constrained, or less ergonomic in common imperative languages.
</span>
</span>
</div>
</td></tr></tbody></table>
<table align="center" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td class="container" style="padding: 15px 15px;">
<div class="text-block">
<span>
<a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Flws.io%2Fblog%2Fif-your-tool-isnt-reachable-by-agents-it-doesnt-exist%2F%3Futm_source=tldrdev/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/W0EZde0sW5MHHbNy74m3qskgcclfqN4YmogfDhrdCdU=452">
<span>
<strong>If Your Tool Isn't Reachable by Agents, It Doesn't Exist (4 minute read)</strong>
</span>
</a>
<br>
<br>
<span style="font-family: "Helvetica Neue", Helvetica, Arial, Verdana, sans-serif;">
As agents become the interface to software, skills and MCP servers can outperform dashboards as a distribution channel by making capabilities discoverable and callable inside the user's existing workflow.
</span>
</span>
</div>
</td></tr></tbody></table>
</td></tr></tbody></table>
<table align="center" bgcolor="" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td align="left" style="word-break: break-word; vertical-align: top; padding: 5px 10px;">
<p style="padding: 0; margin: 0; font-size: 22px; color: #000000; line-height: 1.6; font-weight: bold;">
Love TLDR? Tell your friends and get rewards!
</p>
</td></tr>
<tr><td class="container" style="padding: 0px 10px 15px;">
<div class="text-block">
Share your referral link below with friends to get free TLDR swag!
</div>
</td></tr>
<tr><td align="left" style="padding: 10px;">
<div class="text-block">
<a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Frefer.tldr.tech%2F8770c80a%2F3/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/kJEjIvkY-7z72qint5HTiUa91pNVer86FjdqenMt-pI=452" style="color: #464ba4; text-decoration: underline;">https://refer.tldr.tech/8770c80a/3</a>
</div>
</td></tr>
<tr></tr>
<tr><td align="left" style="padding:5px 10px;">
<a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fhub.sparklp.co%2Fsub_7383e7653c81%2F3/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/XMsEz4AgMXOtzV0KOUqygNb19j3Qq1BDqNgK3N_Yubc=452" style="font-size: 16px; line-height: 1.6; padding: 10px 0; display: inline-block; text-decoration: underline;"><span style="mso-text-raise:13pt; text-decoration: underline;">Track your referrals here.</span></a>
</td></tr></tbody></table>
<table align="center" bgcolor="" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td align="left" style="word-break: break-word; vertical-align: top; padding: 5px 10px;">
<p style="padding: 0; margin: 0; font-size: 22px; color: #000000; line-height: 1.6; font-weight: bold;">
Want to advertise in TLDR? π°
</p>
<div class="text-block" style="margin-top: 10px;">
If your company is interested in reaching an audience of web developers and engineering decision makers, you may want to <a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fadvertise.tldr.tech%2F%3Futm_source=tldrdev%26utm_medium=newsletter%26utm_campaign=advertisecta/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/aBbIcYf2r4anv_hYWbiVkz2Zr8sThbLl4abSLZIR6No=452"><strong><span>advertise with us</span></strong></a>.
</div>
<br>
<!-- New "Want to work at TLDR?" section -->
<p style="padding: 0; margin: 0; font-size: 22px; color: #000000; line-height: 1.6; font-weight: bold;">
Want to work at TLDR? πΌ
</p>
<div class="text-block" style="margin-top: 10px;">
<a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fjobs.ashbyhq.com%2Ftldr.tech/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/fkqe-gEMG9he17L43h4J3JuOuq0yhoySFu6EjsAOUAI=452" rel="noopener noreferrer" style="color: #0000EE; text-decoration: underline;" target="_blank"><strong>Apply here</strong></a>,
<a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fjobs.ashbyhq.com%2Ftldr.tech%2Fc227b917-a6a4-40ce-8950-d3e165357871/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/yNUSVzJkn3wD0fEsTLGnP1ekQh5suMVdLY417zRhagY=452" rel="noopener noreferrer" style="color: #0000EE; text-decoration: underline;" target="_blank"><strong>create your own role</strong></a> or send a friend's resume to <a href="mailto:jobs@tldr.tech" style="color: #0000EE; text-decoration: underline;">jobs@tldr.tech</a> and get $1k if we hire them! TLDR is one of <a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fwww.linkedin.com%2Ffeed%2Fupdate%2Furn:li:activity:7401699691039830016%2F/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/MbgWQfqC92fhd-CJDV1WLYoJBJ_3nv3aSwlt_3QiClo=452" rel="noopener noreferrer" style="color: #0000EE; text-decoration: underline;" target="_blank"><strong>Inc.'s Best Bootstrapped businesses</strong></a> of 2025.
</div>
<br>
<div class="text-block">
If you have any comments or feedback, just respond to this email!
<br>
<br> Thanks for reading,
<br>
<span>Priyam Mohanty</span>, <a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fwww.linkedin.com%2Fin%2Fxu-jenny%2F/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/V2-ScaOkmsqcg-nw4EI6AR2PNNhNVXy5BJ8d_xC0dvk=452"><span>Jenny Xu</span></a> & <span>Ceora Ford</span>
<br>
<br>
</div>
<br>
</td></tr></tbody></table>
<table align="center" bgcolor="" border="0" cellpadding="0" cellspacing="0" width="100%"><tbody><tr><td class="container" style="padding: 15px 15px;">
<div class="text-block" id="testing-id">
<a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Ftldr.tech%2Fdev%2Fmanage%3Femail=silk.theater.56%2540fwdnl.com/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/I7VDYXceRYQBj9cZO_8V9V0Cpw3p09SiaCFbI-a-vs4=452">Manage your subscriptions</a> to our other newsletters on tech, startups, and programming. Or if TLDR Dev isn't for you, please <a href="https://tracking.tldrnewsletter.com/CL0/https:%2F%2Fa.tldrnewsletter.com%2Funsubscribe%3Fep=1%26l=e8d201ca-3e93-11ed-9a32-0241b9615763%26lc=156b9020-84b7-11f0-a976-55fc1d40139c%26p=ba727210-b273-11f1-abe7-313a83b4597c%26pt=campaign%26pv=5%26spa=1789642884%26t=1789643641%26s=3f6a2088fde39a8b3cb61884dd53ce14cfb92a7d3d6d79f36cc4e2780b0aa0dc/1/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/aAh7YcfiMJ0CxP0JzNuCJVTZxA7uFtT3TrhXPo8Lu0c=452">unsubscribe</a>.
<br>
</div>
</td></tr></tbody></table>
</td></tr></tbody></table>
</td></tr></tbody></table>
</td></tr></tbody></table>
</td></tr></tbody></table>
<img alt="" src="http://tracking.tldrnewsletter.com/CI0/010001a0af12d206-4cccb8bb-f17a-4107-9d49-4e24faa5e8f6-000000/n70LTryHyaLIOFZxKw-oWWzajmQgGX7G2K14NO2U3YE=452" style="display: none; width: 1px; height: 1px;">
</body></html>