A coding agent that fits in 636 KB – no Node, no Python, no NPM

Delta Agent, a coding agent released by developer descz, ships as a single C11 executable with no Node, Python, npm, pip or framework dependencies, measuring 636 KB and about 1.7 MB of private memory on Windows. The agent reads and writes files, runs shell commands, handles git with pre-change checkpoints, searches the web, speaks MCP over HTTP or stdio, and keeps durable memory and per-folder JSONL sessions, using models from the models.dev catalog. Only Windows 10/11 x64 is tested, with 283 end-to-end checks; Linux x86_64 builds and runs with 32 checks but its desktop features are untested, and macOS 11+ ships source only and was never tested, while the license prohibits selling or cloning and requires non-profit, credited public disclosure.

License: source is available for study and personal/internal use — selling or cloning is prohibited , and any public disclosure must be non-profit and credited to the project. See LICENSE https://github.com/descz/delta/blob/main/LICENSE . Delta Agent is a coding agent that lives in your terminal. Site: descz.github.io/delta https://descz.github.io/delta/ · downloads: Releases https://github.com/descz/delta/releases/latest You talk in natural language and it does the work: reads and writes files, runs commands, handles git, searches the web, keeps memory and explains what it found — with the model you choose. It is a single executable written in C11, with no dependencies at all : no Node, Python, npm, pip or framework installer. On Windows it is 636 KB and about 1.7 MB of private memory . | Files | reads, creates, edits precisely exact-block edit , searches the project, shows diffs | | Shell | runs commands, keeps background jobs, /terminal shows the output in a chat block | | Git | status, diff, log, commit and checkpoint before changing anything | | Web | downloads pages, extracts data, reads documentation — and speaks MCP over HTTP or stdio | | Skills | saved workflows in SKILL.md — six ship built in code design, spreadsheets/PDF, docs, automation, verification, systematic debugging ; indexed in the system prompt and read on demand | | Memory | durable facts across sessions, searchable by text | | Project graph | indexes symbols and imports once, then answers without re-reading every file | | Models | models.dev https://models.dev catalog with hundreds of models and providers | | Sessions | per-folder history in JSONL with the thinking preserved; delta always starts a new chat, delta continue reopens that folder's last one | | Streaming | token by token, cut immediately when you send a message mid-turn | All inside the terminal, with its own TUI: mouse selection and copy, rendered markdown headings, lists, code, tables , OkLCH colors, themes, i18n pt, en, es, zh, ja and an installer with an HTML screen served by the executable itself . Download from Releases https://github.com/descz/delta/releases/latest . Each system has one file that already is the installer: | system | file | how | |---|---|---| | Windows 10/11 x64 | Delta-windows-x64.zip or Delta.exe | double click → install window HTML popup, native folder picker | | Linux x86 64 | delta-linux-x86 64.run | chmod +x delta-linux-x86 64.run && ./delta-linux-x86 64.run | | macOS 11+ | delta-macos-source.zip | unzip and double click INSTALAR-MAC.command | The installer asks where to keep the data , creates the folder, copies the binary, puts delta on the PATH and creates the shortcut taskbar on Windows, .desktop + GNOME favorites on Linux, Delta.app + Dock on macOS . Windows may warn on SmartScreen the first time More info → Run anyway because the binary is not code-signed. Being explicit, because "compiles" is not "works": | platform | status | |---|---| | Windows 10/11 x64 | Tested — the reference platform: 283 end-to-end checks TUI, streaming, tools, installer, self-update , plus the installer and delta update exercised by hand. | | Linux x86 64 | Builds and runs gcc 13, WSL, 32 checks: build, core, replay, real streaming via curl, installer, self-update . Not exercised on a desktop session : .desktop entry, GNOME favorites and clipboard wl-copy / xclip are untested. | | macOS 11+ | Source only, and not tested — I have no Mac. The release ships the source plus INSTALAR-MAC.command , which checks Xcode Command Line Tools and builds locally; the native layer osascript , .app , Dock was never executed. Treat it as a starting point, not as a supported binary. | There is no ready-made macOS binary: the package ships the source and a .command that checks the Xcode Command Line Tools free , builds and opens the installer — there is no reliable cross-compile to Mach-O. bash $ delta sem chave de API · use /login para colar a chave do provedor /login pick the provider, paste the key, get a default model /projects D:\dev\my-app where it works saved for next time read src/main.c and explain the flow Next time, delta starts a new chat in that folder. To pick up the previous one — messages, tool calls and the model's thinking included — run delta continue . Inside the app, /new starts a fresh session and /clear wipes the screen. | command | what it does | |---|---| | /login /logout | connect/disconnect providers one key per provider | | /models | models from connected providers — the catalog is re-downloaded on every run a model released mid-session shows up and only the providers you connected are kept ; /login still sees the full list | | /thinking | reasoning effort off → max, depending on the model | | /verbosity | how much prose in the reply — low , normal , high ; reasoning and the work itself stay untouched | | /projects <folder | set the working folder saved in config | | /terminal <cmd | runs in your shell and shows the output in the chat | | /undo file | restores a file to its content before the last edit | | /update | installs the newest version from GitHub the app warns at startup when one exists | | /subagentmodel | model the subagents run on it asks before creating one | | /deltagroup | Delta group on Telegram — invite link, copied to the clipboard and clickable | | /status /session | configuration, usage and session | | /new /clear /reload /quit | new session, clear, reload, quit | | /help | all of it on screen | delta --setup reopens the installer: a small HTML window Edge/Chrome app mode, no tabs served by the executable on 127.0.0.1 with a random token — it closes with the window and never leaves a server behind. Without a Chromium browser it falls back to a native terminal screen. delta wiki just prints the docs address. delta update does the same job without opening the app: delta update --check only reports, and the command replaces the running executable in place on Windows it is renamed, so the file can be swapped while it runs . The TUI checks for a new release once a day and shows a notice at startup; turn that off with "updateCheck": false in config.json or DELTA NO UPDATE CHECK=1 . | key | action | |---|---| | Enter / Shift+Enter | send / new line | | Ctrl+C | with a selection: copies it to the clipboard; otherwise stops the generation never closes the app | | Ctrl+Q | returns the last queued message to the editor | | Ctrl+V | paste text, image or file | | mouse | wheel scrolls the conversation; drag selects white background, black text and a plain click clears the selection | | Esc | goes back to the end of the conversation | Typing while it works is supported : the message appears in the chat marked queued and the agent cuts the reply mid-stream to read it — no waiting for the final message. A turn is: prompt → model streaming → tool calls → result → next step , until the model stops. Delta owns the loop and the tools; the model only asks. - Own renderer ui.c : cell grid with OkLCH colors faithful port of OkLch/OkHsl , markdown → Doc of styled lines, tool boxes, multi-line editor with cursor. The transcript is rebuilt incrementally , block by block tr y / tr fast from , keeping a frame at ~0.5 ms even in long conversations. - Terminal term.c : raw mode with ReadConsoleInput on Windows and termios on POSIX; mouse click, wheel, drag , paste, resize, alternate screen and modified-key shortcuts. - Network provider.c : WinHTTP on Windows, curl on POSIX — SSE read line by line, with mid-stream abort when you step in. - Agent agent.c : typed history user / assistant / tool , tool calls with ids, JSONL v3 sessions per folder, system prompt rebuilt every turn with skills indexed and the project graph . - Project graph codegraph.c : indexes files, symbols and imports once into ~/.deltaCore/graphs/<slug .graph ; the agent queries it with the graph tool instead of reading the whole codebase on every input. - Tools tools.c , tools ext.c : 40+ operations grouped in families fs , shell , git , web , skills , mcp , memory , code , assert , agent , extend , with timeouts, output limits and console encoding conversion. Every write keeps an undo snapshot. - Installer setup.c : local HTTP server Winsock/Berkeley serving an embedded page ~13 KB, fonts in base64 , opens the browser and performs the install — native folder picker, binary copy, PATH , shortcuts and pinning. The look themes, color tokens, sizes follows the same vocabulary as a modern editor: 56 theme tokens, plain .json files in themes/ . One folder, chosen at install time default C:\Users\<you \.deltaCore : .deltaCore/ config.json provider, model, language, thinking, projectDir auth.json one API key per provider models.v2.json cached models.dev catalog memory.json durable memory sessions/ --<folder-slug --/<date <id .jsonl skills/ <name /SKILL.md mcps/ one .json per MCP server url or command extensions/ pluggable extensions graphs/ project graph cache symbols/imports update.json last release check version, asset, timestamp system/prompt.md rules it must always follow paste/ jobs/ themes/ undo/ system/prompt.md is re-read every turn: that is where you write your team rules. Several windows at once is supported. Every file in this folder is written to a temporary and swapped in one step file write atomic , so a second delta — or a subagent — never reads a half-written config.json , auth.json , memory.json or catalog. Without that, the instance that reads a truncated config loses provider and key and its session looks dead. You only need a C compiler and the system libc. Windows MinGW-w64 / Git Bash : build.bat :: bin\delta.exe package.bat :: dist\Delta.exe + zip Linux / macOS : ./build.sh bin/delta ./build.sh --test + core tests ./package.sh tarball + .run Linux | .app + zip + dmg macOS On macOS the Xcode Command Line Tools xcode-select --install are enough. At runtime Linux uses curl to talk to the provider. Two suites, no framework: bash tests/run all.sh Windows: 60+ checks TUI replay, provider mock, installer bash tests/run posix.sh Linux/macOS: build, core, replay, real streaming, installer, docs The replay mode runs the real application without a terminal --replay script.txt 110 36 and dumps the screen as text — that is how the TUI is tested in CI. The fake provider tests/mock openai.py covers streaming, tool calls, HTTP errors, retries and mid-stream steering. src/ main.c TUI, commands, editor, transcript agent.c agent loop, sessions, system prompt, config/auth provider.c streaming WinHTTP / curl , tool calls, token usage codegraph.c project graph: files, symbols, imports tools.c fs, shell, git, diff, web, undo tools ext.c skills, mcp HTTP/stdio , memory, code, assert, agent, extend setup.c installer local server + embedded HTML screen ui.c cell grid, markdown, components term.c terminal Win32 / POSIX theme.c okcolor.c themes and OkLCH colors clipboard.c paste text, image, files json.c util.c i18n.c extensions.c modelsdev.c installer/ installer page embedded in the exe docs/ landing page GitHub Pages assets/ logo, hero, screenshots tests/ replay scripts + mocks + suites Source-available, non-commercial. The source is public for study and personal/internal use, but the license forbids selling, renting, paid access and cloning — and requires credit to the product in any public disclosure. | allowed | forbidden | |---|---| | use, study and modify for personal, educational or internal use | sell, rent, charge for access, include in a paid product/service | | share the unmodified copy, non-profit | publish a public fork, mirror, package, binary or clone/rebrand | | cite, write, record videos — with credit | removing credits, the name, the Δ symbol or this notice | Mandatory credit: Delta Agent — https://github.com/descz/delta https://github.com/descz/delta . Commercial permission, cloning or special redistribution: open an issue in the repository.