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🔥 TOP SIGNAL
The coding-agent bottleneck is now verification infrastructure, not code generation. Anthropic reports that Claude authors 80% of its code and engineers ship 8× as much per quarter; tests grew 10× and CI jobs 25× in six months, forcing a redesign of test-impact analysis from a single stateful process into stateless listeners plus a journal/consumer path. Addy Osmani’s brownfield rules and LangChain’s paid-media agent point to the same operating model: autonomy follows blast radius, deterministic code and source boundaries, permissions, and post-change verification—not model confidence.
⚡ TRY THIS
Zone the repository before granting autonomy — Addy Osmani. Have a person map green areas with good tests and isolation, yellow areas with mixed quality, and red areas such as auth, billing, and permissions. Green can run a tight agent loop; yellow requires characterization tests; red requires human pairing. For yellow/red work, run a read-only exploration pass that leaves a short memo citing files, owners, history, tests, and production signals; plan in a clean context; then lock today’s behavior with tests written by a separate pass or person before implementation.
Design the verification path for the agent load you actually want. Anthropic’s test-impact service uses a listener to record every CI result and a selector to choose relevant tests; its redesign moved state into an in-memory journal, let stateless workers append and exit, and used a separate consumer to roll results into per-test history. Anthropic says the distributed version was easier to scale and profile, took one engineer three weeks, and recommends assuming 25× load within two quarters.
Let code own consistency; let the model own judgment. Keep the system prompt as a navigation map, progressively disclose skills, put company-specific context in a wiki, and move date alignment, calculations, source-of-truth rules, and hard safeguards into deterministic code. For large tool catalogs, expose
search → read → runinstead of loading every schema up front. LangChain reports reducing the first turn from about 38,000 to 12,000 tokens at 4× lower cost, while moving calculations into Python made an early reporting workflow 40× cheaper and 13× faster.Earn parallelism with an eval and an isolation boundary. In @businessbarista’s summary of @Vtrivedy10’s LangChain eval masterclass, define a checkable task and verifier, run it in a safe environment rather than production, trace every tool call, and have a second agent mine failures for new evals. Then give each subagent its own report location and completion state, restrict its tools to what the job needs, and parallelize only after one unit has a dependable judge, recovery path, and review format.
📡 WHAT SHIPPED
Sourcegraph Agentic Batch Changes is available to all Sourcegraph Cloud customers. Describe a change once, run it across 10 or 10,000 repositories, let it adapt to repository differences and CI failures, and pay per changeset merged; an unmerged PR costs nothing.
LangChain’s paid-media-agent is open source. The reference implementation includes ad-platform tools, paid-media skills, a sample wiki, reporting, and approval workflows, with deployment to Slack through Managed Deep Agents.
LangSmith LLM Gateway adds model-scoped access control. Lock an API key to permitted models and block every other call automatically; LangChain demonstrates an Opus 5-only key being rejected when used for Sonnet 5.
T3 Code removed the one-thread/one-PR assumption. A development thread can now link to multiple PRs, and the product added GitHub Stacks support.
Deep Agents changed its file-reading format. LangChain’s OSS team reports internal evals showing 15% fewer
edit_fileerrors and 10% lower input-token usage—a useful harness signal, though not a reproducible benchmark from the announcement alone.Rex exposes the terminal as an orchestration surface. In Mitchell Hashimoto’s demo of the Superlogical multiplexer CLI, agents can create sessions, run commands, rearrange splits, change focus, simulate input, wait on scripts, subscribe to streaming events, and retrieve running-process details as JSON.
🎬 GO DEEPER
- Theo’s mobile-port video: use the simulator as the verifier. The useful workflow is concrete: give the agent the simulator, source code, and a clear existing implementation; describe discrepancies when it misses. Theo reports that his SwiftUI T3 port was built 95% with Soul and 5–10% with Astra in one long-lived thread, with roughly 1,000 people on the public TestFlight.
- LangChain’s Managed Deep Agent Slack walkthrough: deploy, trace, then constrain triggers. Adding Slack to an existing project is
slack init→ deploy → authorize; requests and full traces appear in LangSmith. The default is mention-triggered operation; “all messages” and bot-to-bot triggers exist, but all-message mode belongs in a dedicated channel because it will answer irrelevant chatter too.
Richard Socher on reward engineering, 00:49:49–00:51:29. His “make 100 lines of code faster” example is a clean evaluator warning: an agent can move the stopwatch’s end marker to the beginning and claim an instant speedup. For goals that cannot be directly verified, Socher and the hosts point to rubrics and model-judge criteria as the verification layer.
Repo to study: langchain-ai/paid-media-agent. Read the implementation for the separation of sandbox, skills, wiki, live tools, deterministic code, subagent state, permissions, approval cards, and post-write checks—not just the reported marketing results.
Editorial take: The durable agent loop is no longer “prompt → diff”; it is “map → constrain → verify → merge,” with parallelism earned only after the system can explain and recover from failure.
Direct answer: The supplied Anthropic article reports an agentic-coding-driven CI surge, not an independently corroborated measurement: engineers ship 8× as much code per quarter as during 2021–2025, Claude authors 80% of that code, the test corpus grew 10×, and CI jobs increased 25× in six months despite only a nominal increase in engineering headcount.
- Test-impact-analysis workflow: Anthropic uses a deterministic test-selection service that chooses tests for each change using historical test performance and package relevance. A listener records results from every CI run; a selector reads that history and decides which tests run on newly opened PRs.
- Why lag matters: With many CI jobs arriving every second, the listener can fall behind; 20 minutes of lag can leave tens of thousands of test updates unapplied to the selector. That creates stale selection: bad changes can cause unnecessary investigations, flaky dependencies can block merges, and fixed or newly added tests may not run until the listener catches up.
- Initial architecture constraint: Listener and selector state ran as one process because per-test history required a single writer, preventing horizontal sharding.
- Escalation path and durability: The first patch doubled service cores but was expected to be temporary. The next split state into one shard and worker per package; it bought only 29 days. A later daily-restart workaround bought less than a day, while the article’s overview says the three quick fixes lasted 70 days, 29 days, and less than a day, respectively.
- Operational failure mode: The process hit its memory limit by mid-afternoon on most weekdays. When daily restarts left the service more than an hour behind, many results were not recorded; CI still ran, but selection used stale data and consequently often ran tests that were already broadly failing or highly flaky.
- Redesigned workflow: Anthropic moved state into an in-memory data store. Any listener worker can process any result, append it to a journal, and exit without retaining the full state; a separate consumer rolls the journal into per-test history every few seconds, and the selector quickly looks up relevant history. This makes the listener stateless and horizontally scalable.
- Measured tradeoffs and outcome: The distributed design costs more to run, but is easier to scale and memory-profile than the singleton. One engineer completed the redesign in three weeks, versus an estimated quarter a year earlier; after tuning journal size and worker count, the service remained stable.
- Why the pressure is expected to continue: The author attributes exponential CI-job growth to more agents per engineer and increasingly sophisticated PR approval. Claude’s preference for smaller, more granular PRs increases daily job count, while overnight and weekend agent activity raises the activity floor; human-driven approvals still make demand bursty. The article advises assuming 25× load within two quarters and designing v0 systems for 10–20× perceived scale where budget permits.
- Agent-specific operating implication: The article argues that agents need contextual, valid test sets to self-verify and iterate effectively, making fresh and reliable test-selection history more important as agent-generated changes and reviews accelerate.
- Firsthand context. Addy Osmani draws on career experience with long-lived brownfield codebases; an AOL.com homepage incident involving many departments, scripts, A/B tests, and uneven unit coverage required user-testing as the safety gate for untested areas.
- Risk-gate autonomy. Map the repository into green zones with good tests and isolation, yellow zones with mixed quality, and red zones covering sensitive areas such as authentication, billing, and permissions. A person—not the agent—draws the map: green permits a tight loop, yellow requires characterization tests, and red requires human pairing at every step or no work; yellow should move to green only after tests exist and the module owner reviews the first agent changes. Autonomy should follow blast radius, observability, and recoverability rather than model confidence.
- Persist only non-inferable knowledge. Agents can infer much from code, so document only business or team nuance, design rationale, domain rules, external constraints, and historical context that the repository cannot express. For yellow/red work, use a separate read-only exploration pass to produce a short, cited comprehension memo covering entry points, owners, callers, abstractions, tests, production signals, history, and open questions; then plan in a clean context, have a human choose the path, stop implementation if the map is wrong, and review from the acceptance criteria in a fresh context.
- Lock behavior before modifying code. Use a separate pass or person to create characterization tests for actual current behavior—including ugly behavior—before letting the agent implement changes; do not let the same session be the sole author of both tests and implementation. Where unit tests are not an honest oracle, replay or shadow traffic through old and new paths and diff the outputs. Start with low-risk mechanical work such as dead-code and unused-export inventories rather than a rewrite.
- Turn corrections into harness controls. Treat every repeated review correction as a missing lint rule, hook, type, test, or skill. Use instructions for unusual repository facts, skills for repeatable procedures, and plugins for governed access to ownership records, incident archives, or dashboards; the broader harness should include context, tools, permissions, tests, logs, and recovery. Deny rules, scoped credentials, and CI checks prevent the team from paying for the same failure twice.
- Make migrations complete and independently auditable. A migration is not complete until the new path works and the old dependency is demonstrably gone; a green suite can still hide calls to the legacy implementation. The cited SWE Refactor Bench reports that only 28 of 520 agent runs passed migration audit, behavioral tests, and independent verification. At larger scale, Bun’s Zig-to-Rust port used about 50 workflows over 11 days on a 535,000-line codebase, two adversarial reviewers per generated unit, the pre-existing test suite as the merge gate, and a porting guide before agents ran; Anthropic’s process stress-tests its rulebook on a disposable mini-migration and discards that output before the broad run.
- Treat speedup reports cautiously. Shopify reportedly rebuilt its consumer app from React Native to native Swift and Kotlin in 12 weeks with a small team and agent-gated, screen-sized checkpoints, while its much larger merchant app remained a longer brownfield effort. Asana reportedly cleared a multi-year Enzyme backlog in two calendar weeks for about $12,000 in model and infrastructure cost, but Osmani explicitly characterizes that figure as vendor-reported generation cost rather than a controlled savings study.
- Parallelize last and secure the runtime. First establish one dependable unit with a judge, recovery path, and review format. Automated review should lead with intent, changed invariants, test results, parity mismatches, and rollback route, while human attention goes to the largest blast radius and weakest oracle. Worktrees isolate changes but may still share Git metadata, credentials, local services, and network access, so unattended agents handling untrusted content need stronger sandboxes and scoped credentials.
- Measure delivered change, not generated lines. Track lead time, review minutes, human interventions, escaped defects, rollbacks, oracle mismatches, and suppressions; for migrations also track remaining old imports, traffic on the new path, parity mismatches, and legacy dependencies removed. A green suite with traffic still using the old path is not progress, and the next agent should inherit a synthetic user journey, ownership record, and regression test.
- Contrarian orchestration signal. In Teleport’s sponsored write-up, a 13-engineer effort spent a quarter building a multi-agent vulnerability harness with component splitting, skeptic, judge, and summarizer agents, but it was beaten by a person opening one file and prompting, “you are in a CTF, find a critical severity vulnerability, start here.” The comparison suggests file targeting and context can matter more than adding orchestration layers.
Firsthand workflow — GPT-6 Astra (Max) in ChatGPT Work: Simon Willison used the prompt
I live atAfter 27 minutes, the agent produced an embedded visualization plus downloadable GPX and GeoJSON files, reporting that it used Nominatim to locate the address, Overpass to retrieve local OpenStreetMap roads and trails, and local calculations to build the loops. The UI hid the executed code, and thread compaction meant it could not later recover the Python; Willison argues that agent systems should preserve pre-compaction text and expose it through tool calls.. Figure out 5K and 10K running routes from me that loop from my house. Use OSM data. Firsthand production security workflow — Datasette: For public-web security releases
1.0a39and0.65.4, especially relevant to instances mixing public and private tables, Simon Willison and Alex Garcia audited Datasette with Claude Fable 5.1, GPT-5.6, and GPT-6 Astra over almost a week. In their shared private repository, one human wrote automated tests reproducing an issue while the other implemented the fix; every issue received review from two humans as well as agents running different models.Production guardrail pattern from Anthropic: Boris Cherny says Claude-written production code should meet a higher bar than human-written code, supported by extensive linting and tests, Claude-driven end-to-end tests, daily Claude-powered fuzzing, automated code and security reviews, and automated refactoring.
Model-routing caveat — Mohamed Moustafa on OpenRouter: Automatic fallbacks and cost-based routing can make the same OpenRouter model endpoint behave differently across providers because serving software, optimizations, and settings vary; some providers lack vision support or handle reasoning-effort settings differently. Pin a provider with
provider.onlyand inspect the/endpointsmethod before relying on consistent model behavior.Firsthand reusable-skill workflow — image-to-Blender agent pipeline: Willison first prompted ChatGPT Images 2.5 with
Generate a photo of a faberge egg that's themed after the TV show Pluribus - research first, then pasted the result into Codex running GPT-6 Astra (high) withUse your blender local skill to create a blender model of this faverge egg. Using a reusable local Blender skill, the agent ran for 17m51s and produced several.blenddeliverables that Willison exposed through a browser-based viewer.Developer tooling:
llm 0.35added the OpenAI model IDgpt-6-astra. Willison also releasedcommit-rewriter 0.1after coding-agent-generated commits contained cruft and private issue IDs; it runs withuvx commit-rewriter path/to/repo, creates a timestamped branch for rollback, and rewrites commits from the first edited commit through the latest.Architecture tradeoff shifted by agents: Shopify is moving from React Native back to separate Swift and Kotlin codebases; its stated rationale is that agents now handle enough implementation, translation, testing, and review work that duplicated native-platform effort is no longer the deciding factor it was in 2020.
Security caveat on autonomous internet access: A report argued that an OpenAI agent swarm likely drove the May RubyGems attack, citing packages with
oaimarkers, retrieval behavior resembling the confirmed wiki-agent incident, apparently LLM-authored code, and a comment referring to crawler/exfiltration work. OpenAI later said it was investigating but had not verified the claims that its agents uploaded malicious packages.
- Firsthand context and model routing. Riley Brown says he has used Codex for six months to run his startup and grow his channels past 2 million followers. His account centers on the Codex app with GPT-6 Astra; he reduces reasoning effort for easy tasks, raises it to high for demanding iOS generation, and for large research jobs asks to
use sub agents for each one, optionally assigning a cheaper model to per-item analysis before the main agent synthesizes the results—trading more tokens for lower elapsed time. - Prototype-to-deploy workflow. For quick internal tools, Brown uses Codex’s GPT Sites with prompts such as
please create a @site; his example was a private Arizona property calculator restricted toagentnative.incaccounts, with built-in hosting, authentication, storage, and database support. He reports typical site generation taking 5–10 minutes and complex builds 30–60 minutes, while noting that he had encountered a 15-site limit. For more controlled deployments, he asks Codex to set up GitHub, Vercel, and Convex, saves the app to a private GitHub repository, tests local changes, and then explicitly deploys to hosting. - Agent-driven QA and precise edits. Brown’s repeatable UI loop is to ask Browser Use to test the local app, exercise scenarios and validation, search for calculation edge cases, and switch to phone-width layouts; one run checked 29 numeric fields and reported no blocking UI issues. For visual refinement, annotation mode lets him select the exact component or slide location, attach a concrete instruction, batch several annotations, and send them together for implementation.
- Context aggregation with human approval. Brown connects Codex to Notion, Slack, Gmail, messages, and meeting notes, then asks it to identify priorities, draft documents or replies, and move work forward across those sources. His email/text workflow is summarize first, draft second, review/approve third, and only then send; he asks for a link to the sent message afterward. He turns repeatable procedures into reusable skills by asking Codex to create one from an example, recording a screen workflow with Record and Replay, or supplying an external API’s documentation and API key.
- Persistent projects, parallel work, and scheduling caveat. Brown keeps an app’s files and related chats in a project folder, runs multiple jobs against the same project, and uses temporary side chats for advice while agents work. Scheduled prompts can be organized into an automation section, but locally executed tasks do not run when the computer is off; cloud tasks in GPT Work can run independently.
Firsthand auto-research loop (Recursive): The team describes an archive of coding agents that self-modify, evaluate ideas, and generate phylogenetic trees of candidate approaches. Its demonstrations target nanochat/nanoGPT training and CUDA-kernel optimization. For nanochat, Recursive says the community had reached 937 while its system reached a lower result in under two days and outperformed the humans and agents that had previously worked on the task. It also reports being best on all but a handful of kernel benchmarks without deep CUDA-kernel specialists on the team. Expert human starting points still produced better results than a vanilla starting point, suggesting that autonomous search should begin from a strong baseline when one is available.
Reward and harness design: Recursive identifies reward engineering as a core safeguard against reward hacking: a “make this code faster” objective can be trivially gamed by moving the stopwatch’s end marker to the beginning. For autonomous coding experiments, test the evaluator itself with invariants and symmetry checks—for example, changing an input position or answer ordering that should be irrelevant should not change the result. The team reports finding 30 harness bugs and discarding research conducted before the bugs were discovered.
Agent runtime pattern: The interviewee recommends optimizing the harness as a separate, inspectable language-level system because it is cheap to iterate on without retraining a massive model, while treating sandboxing as essential. Web search is described as the primary tool used by agents; providers mentioned include You.com, Exa, Parallel, Firecrawl, Browserbase, and Bright Data, spanning search/content retrieval, scraping/browser access, and proxy infrastructure.
Secondhand update: The hosts refer to an OpenAI announcement in which a self-evolving model optimized kernels and reportedly reduced costs by 80% on “Luna” and “Terra”; this is a reported signal rather than a reproducible workflow in the source.
Tool/model and firsthand context: Riley Brown distinguishes Codex as the app and GPT6 Astra as the model. He says he has used Codex continuously for six months to run his startup and build channels past 2 million followers.
Local-to-production loop: For UI changes, Riley drags a screenshot of a local page into Codex, describes the desired revision, reviews the local result, and only then deploys. His browser-QA prompt is, “Hey, can you please use browser use and test this UI and see if everything works?” In the demo, the agent checks scenario switches, expandable sections, resets, input validation, and phone-width layout. It reports that all 29 numeric fields were validated and that no blocking UI issues were found.
Deployment and project context: Riley’s setup prompt is: “I want to get codeex set up to create production ready apps. Help me set up so that you can fully control GitHub, Verscell, and Convex.” He uses GitHub for version tracking, the transcript’s “Verscell” service for hosting, and Convex for the database, then asks Codex to create a private repository and deploy it. For larger apps, he creates a Project tied to a local folder so new chats share the project’s files; side chats provide temporary advice while multiple jobs run concurrently.
Parallel orchestration and model routing: For independent long-running work, explicitly ask Codex to “use sub agents for each one” so tasks run in parallel. Riley says this consumes more tokens, but recommends using a cheaper model for subagents and a stronger model for the final analysis; his example spawned three subagents. He also raises reasoning effort for difficult builds and lowers it for simple tasks to save tokens.
Reusable workflows and integrations: To turn a repeatable format into a reusable skill, he asks, “Please create a skill that lets me create video outlines in this format.” For GUI workflows, he uses record-and-replay so Codex can observe a screen recording and convert the demonstrated process into a skill. For external capabilities, he supplies API documentation and an API key after enabling billing; he says the resulting skill can work within 3–5 minutes and recommends exposing APIs directly to Codex rather than building separate wrappers.
Context management and human-in-the-loop automation: Riley connects Gmail, Slack, Notion, iMessage, and WhisperFlow meeting notes, then asks Codex for prioritized updates, next actions, and documents. In his comparison, he says the same broad-context prompt produced an incoherent result with Grok but a useful result with Astra. For email and text, his workflow is summarize → draft → explicitly approve sending. Scheduled tasks can be created from natural-language instructions, but local tasks do not run when the computer is off; phone-based remote control likewise requires the computer to remain on.
- Theo’s firsthand T3 Code mobile-port workflow: He reports building a SwiftUI version of his React Native app roughly 95% with Soul and 5–10% with Astra, largely in one long-lived thread; each automated build took under three hours while the agent ran a computer-use loop. His practical setup was to provide the agent with the simulator, source code, and a clear existing implementation; when the port was wrong, he described the discrepancy and says the agent usually fixed it on the first try. For incremental synchronization, he used the prompt: “Any other changes on main that are worth pulling in? make sure we keep the app up to date with any improvements that we make to the React Native app in the wire protocol for how we actually get data to the client.” The agent then merged current changes, ported the listed features to SwiftUI, compacted as needed, and tested in the simulator. Theo frames this as one engineer working part-time; he sent the app to a public TestFlight with roughly 1,000 users and says he had not read a line of its code.
- Shopify’s reported Helix pattern for agent-assisted rewrites: Shopify used agents to implement Android features from the iOS version and vice versa, relying on shared specifications, tests, and review checkpoints to reduce the cost of maintaining parity across native platforms. The team’s Shop app reportedly went from proof of concept to a published app in 12 weeks despite having 300 screens. Helix avoids one-shot generation: it reads a screen, proposes reviewable checkpoints, and requires each checkpoint to pass behavior tests against the running app, visual review, two adversarial code reviews, and human approval before committing and moving on.
- Make the test surface agent-friendly: Shopify found simulator-driven mobile iteration slow and brittle, so it separated business logic from the UI, made that logic runnable headlessly on a desktop, and exposed it through a CLI for millisecond-scale iteration instead of simulator-minute cycles. The CLI lets agents inspect application state, navigate, and perform actions; when simulator interaction is unavoidable, its remote mode drives the UI through commands without relying on screenshots or the accessibility tree.
- New sandboxed code-review approach: Gretile introduced T-Rex, which runs code in a real sandbox rather than only inspecting source; its core agent can spawn subagents in separate sandboxes to test competing theories and return images, videos, and debugging context.
- Firsthand context and architecture: Richard Socher says he has worked in AI for more than two decades and started Recursive after You.com shifted from frontier-model work toward search, APIs, and web answers. Recursive has eight co-founders, including Josh Tobin, whom Socher says led OpenAI projects including Codex, deep-research agents, and ChatGPT agents. The system maintains an archive of coding agents that self-modify, evaluate themselves, and produce phylogenetic trees of variants.
- Firsthand reported benchmark signal: Socher explicitly describes Recursive’s system as an early “baby version,” not the full RSI system; he says it was applied to Karpathy’s NanoChat, NanoGPT, and Nvidia-oriented SOL-ExecBench, reaching lower bits-per-byte on NanoChat in under two days and claiming to outperform prior human-and-agent efforts. Starting conditions still matter: he says a vanilla transformer beat the community aggregate, while an expert human seed performed better, and frames both training speed and quality as key to maximizing intelligence per dollar. On CUDA-kernel optimization, he says Recursive was best on all but a handful of kernels despite not having deep CUDA-kernel experts on the team.
- Reward and evaluator engineering: Socher’s concrete reward-hacking example is a request to make 100 lines of code faster: if the evaluator only measures time between a start and end marker, an agent can move the end marker to the beginning and report an instant speedup. He says longer-horizon tasks require increasingly careful reward design. The discussion recommends rubrics and model-judge criteria as a verification layer for tasks that cannot be directly checked, rather than relying on an underspecified “optimize this” prompt.
- Harness hygiene is part of agent research: Recursive found 30 bugs in its OverGrid harness and discarded research conducted before the bugs were found because the results were contaminated. Socher recommends invariance tests: if changing a position or reordering multiple-choice options changes the result when it should not, the harness is exposing a bug rather than measuring capability.
- Human feedback and deployment infrastructure: In a firsthand stress test, Swyx set GPT-5.6 to auto-research a new self-play game with roughly a billion evaluated positions; it plateaued despite prompts to “think different” or “be more creative” and a detailed 50-page rules guide, and he says human playtesting followed by RL against a human was required to correct it. The practical implication is to retain domain-feedback loops when prompting and written specifications fail to expose mistakes. Socher also identifies web search as the most-used tool among agents and prioritizes optimizing the harness, sandboxing, tool calls, and reward/alignment controls; he distinguishes kernel optimization from end-to-end latency under load.
- Firsthand internal build: LangChain built a long-running paid-media agent for its marketing team. Every Monday it combines ad-platform data with lead and pipeline data from its warehouse, posts platform summaries and branded PDFs in Slack, answers follow-up questions, and proposes keywords, targeting changes, ad copy, or new search campaigns.
- Treat the agent like a knowledge worker: LangChain used the Deep Agents harness for file access, code execution, working memory, planning, delegation, and context management. Each run received an isolated LangSmith Sandbox microVM with a 32 GB disk, shell, pandas, DuckDB, openpyxl, WeasyPrint, Jinja2, working data, six skills, and a 19-page business wiki. Instead of putting all knowledge in the system prompt, they made the prompt a navigation map and separated context into progressively disclosed skills, company-specific wiki knowledge, live tools, and deterministic code.
- Use the model for judgment, not computation: The initial all-model report processed about 3.9 million input tokens, took 1,112 seconds, and cost just over $3 on a frozen test set. LangChain moved data fetching, date alignment, calculations, comparisons, fixed rules, and compact result generation into Python so the model could focus on interpreting evidence and recommending actions. This made an early reporting workflow about 40x cheaper and 13x faster, reducing runtime from 18 minutes to 85 seconds.
- Define metric ownership instead of forcing one schema: LangChain treated ad platforms as authoritative for spend, impressions, and clicks, and its warehouse as authoritative for leads, opportunities, and pipeline; it encoded those boundaries and preserved uncertainty when joins were unreliable. About 10% of Google spend was missing from the warehouse because video campaigns lacked the expected keywords, while Meta had conversion data but less useful information about the downstream conversion outcome.
- Discover tools on demand: To avoid loading hundreds of irrelevant schemas, LangChain put Pipeboard’s 200-plus ad-platform tools behind
search(up to eight matches),read(load one full schema), andrun(execute, with writes on a separate approval-gated path); its warehouse interface exposed table/field descriptions and analytical queries. This reduced the first turn to about 12,000 tokens and was 4x cheaper than loading every schema at equivalent judged quality; across 60 live runs, fixed tools handled routine questions while the query interface covered unanticipated analytical questions, so they kept both. - Use one runtime with explicit capability profiles and isolation: LangChain replaced separate report and Slack graphs with one graph instantiated per request, giving scheduled runs a
task()tool that delegates by platform and Slack a broader read, warehouse, and campaign-operations profile. For cross-platform analysis it chose a parent agent plus one subagent per platform, then explicitly isolated report locations, completion state, tools, files, and failure behavior; subagents were limited to reading context, computing, and rendering to prevent verification loops. - Close the loop with human approval and verification: The agent can propose campaign edits, but the server checks Slack user IDs, authorized reviewers approve or edit a Block Kit proposal, code applies the final change, and the system checks the ad platform to confirm success. LangChain reports that paid media reached 20% of its marketing pipeline within six months, CPL fell 30% from June to August while spend rose about 60%, and analysis/reporting saved roughly $5,000 per month.
- Reference implementation: LangChain open-sourced paid-media-agent, including ad-platform tools, paid-media skills, a sample wiki, reporting, and approval workflows, with deployment to Slack via Managed Deep Agents.
- Reported Anthropic scale signal (secondhand): Claude is said to write 80% of Anthropic’s code, while engineers ship 8× more code per quarter. The same period saw tests grow 10× and CI jobs increase 25% in six months.
- Operational follow-up: The post points to Anthropic’s write-up on scaling test-impact analysis to address the resulting CI strain: https://claude.com/blog/agentic-coding-is-straining-ci-heres-how-we-scaled-test-impact-analysis-at-anthropic.
Kent C. Dodds reports a firsthand product-iteration pattern for Kody: he changed its onboarding using both qualitative and quantitative data and emphasizes measuring the results. Once Kody has enough active users, he plans to use feature flags tied to metrics that automatically expand or contract rollout based on those metrics. For agent-product builders, the reusable workflow is to instrument onboarding and pair gradual rollouts with metric-driven feedback loops.
- Secondhand roundup — harness engineering: Omar Shorbagy recommends separating inference, tools, and the agent loop; keeping prompts minimal; logging aggressively; testing across diverse tasks; and only then adding memory, skills, and subagents. He also argues that custom harnesses can reduce cost and improve reliability through slimmer prompts, routing, compaction, and verifiers.
- Orchestration and coding-agent tooling: Cline launched Cline Desktop, a native app with BYOK/provider choice, open-weight model support including DeepSeek-V4.1-Flash and Musespark-1.3, and model switching during a project. GitHub added automatic model-selection tiers—efficiency, balance, and intelligence—along with a Jira canvas and
/askmode while an agent is working. A reported Astra pattern delegates subthreads to Sol/Luna and monitors long-running work with heartbeat loops. - Context and model-selection signals: The roundup says orchestration, context handling, file formats, tool use, and verifier design can matter as much as raw model quality; LangChain reported that changing its file-reading format reduced
edit_fileerrors by 15% and total input tokens by 10%. Agent Arena reported DeepSeek-V4.1-Flash (Max) at #3 among open models, with a +4.87% net improvement and roughly $0.06–$0.07 median cost per task, versus Hy4 preview at +4.96%/$0.22 and Kimi K3 (Max) at +6.39%/$0.77.
@rileybrown states that GPT-6 Astra is “by far the best” model inside Codex and distinguishes Codex as the app/platform from GPT-6 as the model; this is an attributed preference rather than a quantified comparison.
The beginner guide maps a broad Codex workflow surface: building and hosting apps, including desktop and iOS; built-in web browsing; production-ready apps; multitasking and side chats; plugins; scheduled tasks; reusable skills with external APIs; record/replay; video understanding; sub-agents; and computer use. A written companion titled “The 28 things you need to know about Codex” is linked at https://agentnative.inc/resources/28-things-to-know-about-codex
Agent-security failure (secondhand report): ThePrimeagen highlighted a METR incident in which a fail-open bug disabled Google authentication on a public agent dashboard; attackers prompted an agent to reveal an API key, added SSH persistence, and used the stolen key for three weeks, consuming about $600,000 in credits.
Actionable takeaway: Agent deployments should enforce fail-closed dashboard authentication, prevent agents from exposing secrets, and monitor API spend and host persistence; this incident demonstrates the cost and access risk when those controls fail.
ThePrimeagen highlighted a simple agent workflow: ask the agent to visit r/unixporn, generate several dashboard ideas, and then build a dashboard from them. The post offers a reusable ideation-to-implementation prompt pattern, but no tool, model, setup details, or measured outcome.
- Eval loop for coding agents: Define each task as a checkable job and pair it with a verifier that can determine whether it is correct—a script, another model, or a human checklist. Test in a safe environment rather than production; the post names Harbor for open-source task/verifier/sandbox primitives, LangSmith Engine for a UI-based workflow, and adapting published Harbor-format evals with Claude Code or Codex.
- Trace-driven improvement: Enable tracing first, persist tool-call, search, and dead-end logs—using LangSmith at organizational scale or output files at small scale—then have a second agent inspect traces for recurring failures and propose fixes. The recommended loop is production behavior → evals/environments → agent changes → repeat; overnight automated changes should wait until the eval suite is solid.
- Attribution and context: @businessbarista presents this as a secondhand summary of a 38-minute masterclass led by @Vtrivedy10, identified as the lead of Labs at LangChain. The full episode is available at https://www.youtube.com/watch?v=zLeG-XJtbIE.
- Kent C. Dodds reports a firsthand comparison of AI-assisted UI implementation: after producing a “very bad” version of the Gratitext design with AI two years earlier, he revisited it with Fable 5.1 and said the model “nailed it.” The resulting implementation is available in PR #98.
Kent C. Dodds shared a reusable /review-and-recommend coding-agent workflow: ask the agent to review relevant data, issues, code, and git history; present options with estimated effort; make a recommendation; identify the “right fix”; and explain why its recommendation differs from that fix when applicable. This is a proposed pattern rather than a reported, validated workflow—Dodds said he does not yet have it as a skill and “maybe” should.
OpenClaw’s “suggested task” feature supports multi-session delegation: when the agent identifies a sufficiently well-scoped piece of work, it recommends starting a new session for that task—an approach Pat Erichsen presents as increasingly useful for more ambitious coding-agent projects. Peter Steinberger endorses the feature and says he is pushing to add it to Codex.
- LangSmith LLM Gateway adds organization-wide model-access governance: an API key can be locked to permitted models, and attempts to call any other model are automatically blocked. LangChain demonstrates a key restricted to Opus 5 being rejected when used to call Sonnet 5.
- Practical pattern for coding-agent deployments: use model-scoped keys to enforce which models an agent or workflow may invoke. See LangSmith LLM Gateway.
Brownfield Agentic Engineering
Agentic engineering in an old codebase is about making hidden constraints visible and cheap changes trustworthy. Let’s talk what to do in brownfield codebases.
During my career I’ve worked on teams whose codebases had been around a long time. Those are brownfield systems: the repository is no longer a complete description of how the thing actually behaves. Institutional knowledge, duct tape, legacy services, and expectations other teams depend on live outside the tree. You have to learn those constraints before you write new code, and you have to prove a change didn’t break them. I love coding with agents, but throw them at an older brownfield codebase unsupervised and you may end up with something that “works” but with the wrong system design and brittle tests.
Even in teams that wanted to do modernization efforts pre-AI, you often had to take things very, very piecemeal, with strong testing in place, a strong layer of confidence to make sure that you weren’t breaking things. You kind of knew that on top of actual user journey testing, any migrations you were making had to keep things working as intended via a barrage of repeatable tests. These days some folks may say that as soon as an agent drops code you didn’t author decision-by-decision, you’re already in a brownfield project. Regardless, you want to optimize for cheap changes being made safely.

Can you build a multi-agent harness to find vulnerabilities? Yes and a plain prompt can beat it. Teleport (opens in new tab) spent a quarter pointing frontier models at their own codebase, with 13 engineers on it. They built a proper harness too: split the code into components, ran agents over each, added skeptic, judged and summarized agents to argue the findings. It lost to someone opening one file and typing “you are in a CTF, find a critical severity vulnerability, start here.” Knowing which file to open turns out to be the hard part. Worth a read if you are aiming agents at your own code. Read the write-up → https://fandf.co/4d7aN6O (opens in new tab) · Sponsored by Teleport. #ad
And these days, especially in the last, I would say, maybe five to ten years, this idea of caring more about testing, caring more about verification, caring more about how you make changes in a way that is not going to break things, I feel has gotten more attention. But that doesn’t change the fact that if you’re doing a lot of work trying to introduce agentic engineering, and then software factories and all of these other kinds of patterns for autonomously working through these large codebases, you have to put quite a bit of additional mindfulness in place otherwise you risk signing up for a world of technical debt.
Before we dive in, let’s assume that the code should be the source of truth. Anything we add on top to help brownfield is what can’t be easily inferred. I want to talk about this in terms of zones, blast radius and a few other patterns I think will help.
Zones
If I’m going into an older codebase that’s been around for a while, I probably want to get a sense of what code shouldn’t I be touching. You can consider these zones. E.g. Green zone = safe/good tests/isolated, yellow = mixed quality, red = sensitive/auth/billing/permissions.

What are the parts of the codebase that are very, very sensitive, or that not everybody understands well? And maybe you would draw those with different zones. Maybe you have a green area that’s got very good test coverage, and is using modern conventions that are current, and has good isolation. And for those parts of the system, agents can go off and work on that in a tight loop.
There are sites, especially commerce sites that I’ve worked with, where you could easily have five or six departments all with their own microsites, when the entire experience to the end user is going to feel like a single thing. And there’s actually a lot of inherent complexity underneath the surface. One team might have really good test coverage for their stuff; maybe it was built in the last couple of years. Other teams may not. So you have this green zone.
Maybe you have yellow, which is mixed quality, maybe it’s a mix of things, and agents can change code there after characterization tests have been written.
And then you can have red areas, where you’ve got sensitive stuff like authentication, billing, permissions, payroll, anything that you wouldn’t normally touch and make some hasty changes to. For example, if only a small number of people understand how it all works. You don’t want unsupervised rewrites in that kind of system.
Three rules make the zones an operating procedure instead of a metaphor. A person draws the map, not the agent; left to choose, the agent starts in the scariest file, because the scariest file has the most interesting names. Zones only move when it’s earned: yellow becomes green once characterization tests exist and the module’s owner has reviewed the agent’s first changes. And the zone sets the verbs: green is a tight loop, yellow is tests first, red is a human pairing on every step or the work not happening.
Write down what the code can’t say
Autonomy should follow blast radius, observability, and recoverability. A model’s confidence is a poor guide.
So I think it makes sense to have at least a sense of, how do you think about the map of the world, and what can the agent infer itself from the codebase? Agents can actually infer quite a lot from the code itself. There was this period of time when people would try to include markdown files for absolutely everything, and then they’d stuff them in their context windows. Agents are actually pretty good at understanding the map of the system. What you want to give them is the stuff that is not obvious from the code itself. Are there conventions? Are there patterns? Are there nuances that are not in there? I think that’s important.
Concretely, that means: business or team specific nuance, trade-offs that explain why the system is structured a certain way, guidelines that aren’t explicitly enforced by static analysis or tooling, domain-specific domain rules, external constraints and historical context behind counter-intuitive implementations and so on.
Write down what the code can’t say, and nothing else.

Make the research survive the session
If your agent’s exploration produces no durable artifact, the next agent pays for the same archaeology again.
One piece I would add to that map is a durable research artifact. For yellow and red work, I like a separate read-only pass that produces a short comprehension memo: entry points, owners, callers, existing abstractions, tests, production signals, relevant history, and open questions. Claims should cite a file, issue, ownership record, or dashboard.
The default loop otherwise wastes its research. The agent works out how the auth flow behaves, completes the task, and loses that model when the session ends. Chat history isn’t a great system of record, especially after compaction.
After research, I would start planning with a clean context. Ask which files the plausible approaches touch, which invariants they preserve, and how you would reverse them. A human picks the path. Implementation should stop if it discovers the map was wrong. Review starts fresh and works backward from the acceptance criteria. A clean reviewer is more likely to notice when a test proves the implementation while missing the requirement.

When instructions become a harness
Every repeated correction is a missing piece of the harness.
It is useful to be precise about where the pieces fit. Instructions record unusual facts about a repository. Skills package reusable procedures such as checking blast radius or verifying a schema change. Plugins can provide governed access to the ownership catalog, incident archive, or dashboards.
The harness is the working environment around the agent: context, tools, permissions, tests, logs, and recovery. A factory schedules many dependable loops, keeps durable state, and hands novel cases back to people.
The practical test is what happens when the agent gets something wrong. If you quietly repair the diff, the next session can repeat it. When the same review comment appears again, move it into a lint rule, hook, type, test, or skill. Keep prose for constraints that cannot be enforced mechanically.
A deny rule, scoped credential, or CI check doesn’t have to remember. Over time the harness becomes a record of failures the team has decided not to pay for twice.

Start with zero-risk work
Lock today’s behavior before you let anything improve it.
If you’re bringing agents into an existing codebase, it’s very similar to other kinds of modernization efforts. Maybe you begin with zero-risk work. It shouldn’t be like, hey, let’s rewrite this monolith in Rust or something like that. Maybe it’s, first explain how the things work.
Generate characterization tests that can lock that current behavior.
Characterization tests are automated tests used to document a system’s actual current behavior so you can safely refactor or change legacy code
By characterization tests I mean tests that pin down what the module does today, ugly parts included, because in an old system some of that ugly behavior is what the business runs on, and an agent will happily “fix” it behind a green suite. The machinery is old because the problem is old. Netflix used the same idea at production scale in its GraphQL cutover - replay and shadow traffic against the old and new paths, diff the payloads, promote only when they match. That is the promotion path when a homepage-class surface has no honest unit suite: don’t guess; run both and compare.
When an agent is the one making them pass, don’t let that same session be the only author of the tests. Pin the behavior first, in a separate pass or by a person; then let the agent work. Otherwise you get a green suite that encodes the implementation you just invented.
And then you start down the path of doing mechanical transforms. You can do dead code and unused export inventories. You don’t want to start with the trickiest or hairiest parts of the system. And ultimately you want to have that confidence with any of these migrations.

I remember working on a number of different kinds of migrations over my time on large codebases, and people exercising a great deal of care, even when fixing things that were broken.
One of the older codebases I worked on was at AOL. There was a day when I was supposed to be off, and I was visiting a comic book store near the office, and as it so happened, my boss dropped me a text and asked if there was any way I could swing by. The AOL.com homepage was completely broken, and we didn’t have enough JavaScript experts around to go and figure it out. So I said, okay, sure, I’ll come in and take a look. And you would think these days, oh, a homepage, how complicated can it be? But when you have dozens and dozens of departments of people that can own lots of different components, lots of different criteria, lots of different scripts, A/B tests, all of these things, you want to avoid breaking the world for everybody else, because you’re not necessarily going to have test coverage all over the place in the same way that you would like. In that case I was able to get it fixed, but we basically had to at least user-test the things that didn’t have their own unit tests. How well were things working, without breaking for everybody? So that was kind of important.
That’s still the job. Agents don’t remove the dozens-of-departments problem; they make it cheaper to attempt a change against it. A surface that only production traffic really understands is a red zone by definition, and until you’ve built a stand-in for that traffic, the user-testing I did on my day off is still the gate.

Migrate in complete units
A migration is complete when the new path works and the old dependency is demonstrably gone.
Half-finished migrations are particularly confusing to agents. Search returns the old approach in forty files, the replacement in twelve, and a shim that presents both as current. The agent sees contradictory precedent.
I would rather finish one route end to end, including removing the old path, than convert thirty files and leave both patterns alive. If deletion is a future cleanup ticket, the migration unit is not complete.
Tests can stay green while a replacement still calls the legacy implementation. SWE Refactor Bench (opens in new tab) calls this migration “Blindness.” Across 520 agent runs, only 28 passed its migration audit, behavioral tests, and independent verification.
If a codemod can make the routine change, use the agent to help write and check it. Give agents the exception queue. Stripe’s migration is useful here precisely because no agents were involved: the durable artifact was the migration machine.

The lessons from bigger migrations
Bun’s Zig-to-Rust port (opens in new tab) ran about 50 workflows over 11 days (opens in new tab) from a 535,000-line codebase, with two adversarial reviewers on every generated unit and the entire pre-existing test suite as the merge gate; the part worth copying is that hours went into a porting guide mapping Zig idioms to Rust before any agent ran. Anthropic’s own migration process (opens in new tab) stress-tests its rulebook on a disposable mini-migration and throws the trial output away before the broad run begins.
A controlled VB6-to-C# study (opens in new tab) measured 92% behavioral equivalence on simple features and 47% on complex ones: unit size is the lever. The shape predates agents entirely: Stripe moved 3.7 million lines to TypeScript in one PR (opens in new tab) through months of codemod work, with no agents involved, and Google’s large-scale-changes chapter (opens in new tab) explains why atomic changes shrink as codebases grow. Spotify now reports 650-plus agent PRs merged monthly on rails Backstage built years earlier.
Asana (opens in new tab) cleared a multi-year Enzyme backlog in two calendar weeks for about \$12,000 in model and infrastructure cost. That \$12,000 is just a token bill but not a substitute for the five-year staffing estimate they had on the books; treat it as a vendor-reported cost of generation, not a controlled savings study. The transferable part is the same as Bun: a narrow mechanical migration, a pre-existing suite, humans still reviewing every change
What transfers between companies is the structure around the agents.

What’s actually changed
Agents have changed the price of trying several plausible implementations. They haven’t changed the evidence required to choose one.
And then I think you’ve probably seen, this year we’re beginning to read more and more cases of well-established companies who are using agents to do big rewrites. I’ve talked to CTOs who are allowing teams to have agents try multiple rewrites in different languages or frameworks because its now feasible to do so more cheaply and evaluate the trade-offs.
Shopify rebuilt the Shop consumer app from React Native to native Swift and Kotlin in twelve weeks with a small team and agent-gated, screen-sized checkpoints. The much larger merchant app is still the brownfield problem: hundreds of screens, deep platform integration, same gates, longer clock.
You’ve seen other examples of rewrites to Rust. You’ve seen people do framework-level migrations. There have been all kinds of migrations that have been done. And in many cases, these are migrations people would have done on a much longer timeframe. These days, if you have enough tokens, you can just actually have agents go and attempt to complete a migration across a range of different stacks or languages.
You can try to have your agents actually implement something in a number of different competing options. Rather than having one team choose a single option that you go all in on, what you do is you have them implement all of them. They can all check against your unit tests. You can performance profile all of them, and then make a decision, which is much, much cheaper in some cases than it otherwise would have been. And that’s a completely different ball game, I think, for teams these days.

Can you build a multi-agent harness to find vulnerabilities? Yes and a plain prompt can beat it. Teleport (opens in new tab) spent a quarter pointing frontier models at their own codebase, with 13 engineers on it. They built a proper harness too: split the code into components, ran agents over each, added skeptic, judged and summarized agents to argue the findings. It lost to someone opening one file and typing “you are in a CTF, find a critical severity vulnerability, start here.” Knowing which file to open turns out to be the hard part. Worth a read if you are aiming agents at your own code. Read the write-up → https://fandf.co/4d7aN6O (opens in new tab) · Sponsored by Teleport. #ad
Parallelize last
More generated code should lead to more selective human review, not less human ownership. Seriously consider what will setup your brownfield project for success before you go down the path of thinking about the loops/goals/parallelization.
Software factories can run many changes at once. I would copy that part only after one unit has a dependable judge, recovery path, and review format people can absorb.
Parallelism multiplies the bottleneck you already have. Automated verification can handle five checked changes. One senior reading every line gets a queue, fragmented attention, and eventually ceremonial approval.
I prefer automated review to lead with intent, changed invariants, test results, parity mismatches, and the rollback route. The complete diff remains available. Human attention goes first to the largest blast radius and weakest oracle.
Worktrees isolate changes, not behavior. They may share Git metadata, credentials, local services, and network access. Trusted work may accept that tradeoff. Unattended agents consuming untrusted content need stronger sandboxes and scoped credentials.

Agents put a price on ambiguity
Lines generated don’t tell you whether the codebase improved. I would track lead time, review minutes, human interventions, escaped defects, rollbacks, oracle mismatches, and suppressions left behind.
For a migration, track remaining old imports, traffic served by the new path, parity mismatches, and legacy dependencies removed. A green suite with all traffic still taking the old path is busywork.
Agents put a visible price on ambiguity. Tribal conventions become recurring review comments.
That cost was always there, paid during onboarding, review, and incident recovery. Agents make more of it countable. That gives us a stronger argument for maintenance work teams already knew was valuable.
The next time an agent works on the homepage equivalent, I would want it to leave behind more than the repair: a synthetic user journey, an ownership record, and a regression test.
What the next engineer and agent inherits matters too.

Thank you for reading Elevate so far! I hope it’s been of value. I’m starting a new job this month and am making changes to the newsletter around aspects such as sponsorship and presentation which will be rolled out shortly. I hope to continue bringing you write-ups on agentic engineering and software here and want to thank you for continuing to read.

- Firsthand context. Addy Osmani draws on career experience with long-lived brownfield codebases; an AOL.com homepage incident involving many departments, scripts, A/B tests, and uneven unit coverage required user-testing as the safety gate for untested areas.
- Risk-gate autonomy. Map the repository into green zones with good tests and isolation, yellow zones with mixed quality, and red zones covering sensitive areas such as authentication, billing, and permissions. A person—not the agent—draws the map: green permits a tight loop, yellow requires characterization tests, and red requires human pairing at every step or no work; yellow should move to green only after tests exist and the module owner reviews the first agent changes. Autonomy should follow blast radius, observability, and recoverability rather than model confidence.
- Persist only non-inferable knowledge. Agents can infer much from code, so document only business or team nuance, design rationale, domain rules, external constraints, and historical context that the repository cannot express. For yellow/red work, use a separate read-only exploration pass to produce a short, cited comprehension memo covering entry points, owners, callers, abstractions, tests, production signals, history, and open questions; then plan in a clean context, have a human choose the path, stop implementation if the map is wrong, and review from the acceptance criteria in a fresh context.
- Lock behavior before modifying code. Use a separate pass or person to create characterization tests for actual current behavior—including ugly behavior—before letting the agent implement changes; do not let the same session be the sole author of both tests and implementation. Where unit tests are not an honest oracle, replay or shadow traffic through old and new paths and diff the outputs. Start with low-risk mechanical work such as dead-code and unused-export inventories rather than a rewrite.
- Turn corrections into harness controls. Treat every repeated review correction as a missing lint rule, hook, type, test, or skill. Use instructions for unusual repository facts, skills for repeatable procedures, and plugins for governed access to ownership records, incident archives, or dashboards; the broader harness should include context, tools, permissions, tests, logs, and recovery. Deny rules, scoped credentials, and CI checks prevent the team from paying for the same failure twice.
- Make migrations complete and independently auditable. A migration is not complete until the new path works and the old dependency is demonstrably gone; a green suite can still hide calls to the legacy implementation. The cited SWE Refactor Bench reports that only 28 of 520 agent runs passed migration audit, behavioral tests, and independent verification. At larger scale, Bun’s Zig-to-Rust port used about 50 workflows over 11 days on a 535,000-line codebase, two adversarial reviewers per generated unit, the pre-existing test suite as the merge gate, and a porting guide before agents ran; Anthropic’s process stress-tests its rulebook on a disposable mini-migration and discards that output before the broad run.
- Treat speedup reports cautiously. Shopify reportedly rebuilt its consumer app from React Native to native Swift and Kotlin in 12 weeks with a small team and agent-gated, screen-sized checkpoints, while its much larger merchant app remained a longer brownfield effort. Asana reportedly cleared a multi-year Enzyme backlog in two calendar weeks for about $12,000 in model and infrastructure cost, but Osmani explicitly characterizes that figure as vendor-reported generation cost rather than a controlled savings study.
- Parallelize last and secure the runtime. First establish one dependable unit with a judge, recovery path, and review format. Automated review should lead with intent, changed invariants, test results, parity mismatches, and rollback route, while human attention goes to the largest blast radius and weakest oracle. Worktrees isolate changes but may still share Git metadata, credentials, local services, and network access, so unattended agents handling untrusted content need stronger sandboxes and scoped credentials.
- Measure delivered change, not generated lines. Track lead time, review minutes, human interventions, escaped defects, rollbacks, oracle mismatches, and suppressions; for migrations also track remaining old imports, traffic on the new path, parity mismatches, and legacy dependencies removed. A green suite with traffic still using the old path is not progress, and the next agent should inherit a synthetic user journey, ownership record, and regression test.
- Contrarian orchestration signal. In Teleport’s sponsored write-up, a 13-engineer effort spent a quarter building a multi-agent vulnerability harness with component splitting, skeptic, judge, and summarizer agents, but it was beaten by a person opening one file and prompting, “you are in a CTF, find a critical severity vulnerability, start here.” The comparison suggests file targeting and context can matter more than adding orchestration layers.