Add frontend render plugin system support

contrib/render-plugins/example-wasm/README.md

@@ -0,0 +1,51 @@
+# Go + WASM Render Plugin Example
+
+This example shows how to build a frontend render plugin whose heavy lifting
+runs inside a WebAssembly module compiled from Go. The plugin loads the WASM
+binary in the browser, asks Go to post-process the fetched file content, and
+then renders the result inside the file viewer.
+
+## Files
+
+- `manifest.json` — plugin metadata consumed by the Gitea backend
+- `render.js` — the ES module entry point that initializes the Go runtime and
+  renders files handled by the plugin
+- `wasm/` — contains the Go source that compiles to `plugin.wasm`
+- `wasm_exec.js` — the Go runtime shim required by all Go-generated WASM
+  binaries (copied verbatim from the Go distribution)
+- `build.sh` — helper script that builds `plugin.wasm` and produces a zip
+  archive ready for upload
+
+## Build & Install
+
+1. Build the WASM binary and zip archive:
+
+   ```bash
+   cd contrib/render-plugins/example-wasm
+   ./build.sh
+   ```
+
+   The script requires Go 1.21+ on your PATH. It stores the compiled WASM and
+   an installable `example-go-wasm.zip` under `dist/`.
+
+2. In the Gitea web UI, visit `Site Administration → Render Plugins`, upload
+   `dist/example-go-wasm.zip`, and enable the plugin.
+
+3. Open any file whose name ends with `.wasmnote`; the viewer will show the
+   processed output from the Go code running inside WebAssembly.
+
+## How It Works
+
+- `wasm/main.go` exposes a single `wasmProcessFile` function to JavaScript. It
+  uppercases each line, prefixes it with the line number, and runs entirely
+  inside WebAssembly compiled from Go.
+- `render.js` injects the Go runtime (`wasm_exec.js`), instantiates the compiled
+  module, and caches the exported `wasmProcessFile` function.
+- During initialization the frontend passes the sniffed MIME type and the first
+  1 KiB of file data to the plugin (`options.mimeType`/`options.headChunk`),
+  allowing renderers to make decisions without issuing extra network requests.
+- During rendering the plugin downloads the target file, passes the contents to
+  Go, and displays the transformed text with minimal styling.
+
+Feel free to modify the Go source or the JS wrapper to experiment with richer
+interfaces between JavaScript and WebAssembly.

contrib/render-plugins/example-wasm/build.sh

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+#!/usr/bin/env bash
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+cd "$SCRIPT_DIR"
+
+BUILD_DIR="$SCRIPT_DIR/.build"
+DIST_DIR="$SCRIPT_DIR/dist"
+ARCHIVE_NAME="example-go-wasm.zip"
+
+rm -rf "$BUILD_DIR"
+mkdir -p "$BUILD_DIR" "$DIST_DIR"
+
+export GOOS=js
+export GOARCH=wasm
+
+echo "[+] Building Go WASM binary..."
+go build -o "$BUILD_DIR/plugin.wasm" ./wasm
+
+cp manifest.json "$BUILD_DIR/"
+cp render.js "$BUILD_DIR/"
+cp wasm_exec.js "$BUILD_DIR/"
+
+( cd "$BUILD_DIR" && zip -q "../dist/$ARCHIVE_NAME" manifest.json render.js wasm_exec.js plugin.wasm )
+
+echo "[+] Wrote $DIST_DIR/$ARCHIVE_NAME"

contrib/render-plugins/example-wasm/manifest.json

@@ -0,0 +1,11 @@
+{
+  "schemaVersion": 1,
+  "id": "example-go-wasm",
+  "name": "Example Go WASM Renderer",
+  "version": "0.1.0",
+  "description": "Demonstrates calling a Go-compiled WebAssembly module inside a Gitea render plugin.",
+  "entry": "render.js",
+  "filePatterns": [
+    "*.wasmnote"
+  ]
+}

contrib/render-plugins/example-wasm/render.js

@@ -0,0 +1,163 @@
+const wasmUrl = new URL('plugin.wasm', import.meta.url);
+const wasmExecUrl = new URL('wasm_exec.js', import.meta.url);
+let wasmBridgePromise;
+let styleInjected = false;
+
+function injectScriptOnce(url) {
+	return new Promise((resolve, reject) => {
+		const existing = document.querySelector(`script[data-go-runtime="${url.href}"]`);
+		if (existing) {
+			if (existing.dataset.loaded === 'true') {
+				resolve();
+			} else {
+				existing.addEventListener('load', resolve, {once: true});
+				existing.addEventListener('error', reject, {once: true});
+			}
+			return;
+		}
+		const script = document.createElement('script');
+		script.dataset.goRuntime = url.href;
+		script.src = url.href;
+		script.async = true;
+		script.addEventListener('load', () => {
+			script.dataset.loaded = 'true';
+			resolve();
+		}, {once: true});
+		script.addEventListener('error', reject, {once: true});
+		document.head.appendChild(script);
+	});
+}
+
+function sleep(ms) {
+	return new Promise((resolve) => setTimeout(resolve, ms));
+}
+
+async function waitForExport(name, timeoutMs = 2000) {
+	const start = Date.now();
+	while (typeof globalThis[name] !== 'function') {
+		if (Date.now() - start > timeoutMs) {
+			throw new Error(`Go runtime did not expose ${name} within ${timeoutMs}ms`);
+		}
+		await sleep(20);
+	}
+	return globalThis[name];
+}
+
+async function ensureWasmBridge() {
+	if (!wasmBridgePromise) {
+		wasmBridgePromise = (async () => {
+			if (typeof globalThis.Go === 'undefined') {
+				await injectScriptOnce(wasmExecUrl);
+			}
+			if (typeof globalThis.Go === 'undefined') {
+				throw new Error('Go runtime (wasm_exec.js) is unavailable');
+			}
+			const go = new globalThis.Go();
+			let result;
+			const fetchRequest = fetch(wasmUrl);
+			if (WebAssembly.instantiateStreaming) {
+				try {
+					result = await WebAssembly.instantiateStreaming(fetchRequest, go.importObject);
+				} catch (err) {
+					console.warn('instantiateStreaming failed; falling back to ArrayBuffer', err);
+					const buffer = await (await fetchRequest).arrayBuffer();
+					result = await WebAssembly.instantiate(buffer, go.importObject);
+				}
+			} else {
+				const buffer = await (await fetchRequest).arrayBuffer();
+				result = await WebAssembly.instantiate(buffer, go.importObject);
+			}
+			go.run(result.instance);
+			const processFile = await waitForExport('wasmProcessFile');
+			return {
+				process(content) {
+					const output = processFile(content);
+					return typeof output === 'string' ? output : String(output ?? '');
+				},
+			};
+		})();
+	}
+	return wasmBridgePromise;
+}
+
+async function fetchFileText(fileUrl) {
+	const response = await window.fetch(fileUrl, {headers: {'Accept': 'text/plain'}});
+	if (!response.ok) {
+		throw new Error(`failed to fetch file (${response.status})`);
+	}
+	return response.text();
+}
+
+function ensureStyles() {
+	if (styleInjected) return;
+	styleInjected = true;
+	const style = document.createElement('style');
+	style.textContent = `
+.go-wasm-renderer {
+	font-family: var(--fonts-proportional, system-ui);
+	border: 1px solid var(--color-secondary);
+	border-radius: 6px;
+	overflow: hidden;
+}
+.go-wasm-renderer__header {
+	margin: 0;
+	padding: 0.75rem 1rem;
+	background: var(--color-secondary-alpha-20);
+	font-weight: 600;
+}
+.go-wasm-renderer pre {
+	margin: 0;
+	padding: 1rem;
+	background: var(--color-box-body);
+	font-family: var(--fonts-monospace, SFMono-Regular, monospace);
+	white-space: pre;
+	overflow-x: auto;
+}
+.go-wasm-renderer__error {
+	color: var(--color-danger);
+}
+`;
+	document.head.appendChild(style);
+}
+
+function renderError(container, message) {
+	container.innerHTML = '';
+	const wrapper = document.createElement('div');
+	wrapper.className = 'go-wasm-renderer';
+	const header = document.createElement('div');
+	header.className = 'go-wasm-renderer__header';
+	header.textContent = 'Go WASM Renderer';
+	const body = document.createElement('pre');
+	body.className = 'go-wasm-renderer__error';
+	body.textContent = message;
+	wrapper.append(header, body);
+	container.appendChild(wrapper);
+}
+
+export default {
+	name: 'Go WASM Renderer',
+	async render(container, fileUrl) {
+		ensureStyles();
+		try {
+			const [bridge, content] = await Promise.all([
+				ensureWasmBridge(),
+				fetchFileText(fileUrl),
+			]);
+
+			const processed = await bridge.process(content);
+			const wrapper = document.createElement('div');
+			wrapper.className = 'go-wasm-renderer';
+			const header = document.createElement('div');
+			header.className = 'go-wasm-renderer__header';
+			header.textContent = 'Go WASM Renderer';
+			const body = document.createElement('pre');
+			body.textContent = processed;
+			wrapper.append(header, body);
+			container.innerHTML = '';
+			container.appendChild(wrapper);
+		} catch (err) {
+			console.error('Go WASM plugin failed', err);
+			renderError(container, `Unable to render file: ${err.message}`);
+		}
+	},
+};

contrib/render-plugins/example-wasm/wasm/main.go

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"fmt"
+	"strings"
+	"syscall/js"
+)
+
+func processFile(this js.Value, args []js.Value) any {
+	if len(args) == 0 {
+		return js.ValueOf("(no content)")
+	}
+	content := args[0].String()
+	lines := strings.Split(content, "\n")
+	var b strings.Builder
+	b.Grow(len(content) + len(lines)*8)
+	for i, line := range lines {
+		fmt.Fprintf(&b, "%4d │ %s\n", i+1, strings.ToUpper(line))
+	}
+	return js.ValueOf(b.String())
+}
+
+func main() {
+	js.Global().Set("wasmProcessFile", js.FuncOf(processFile))
+	select {}
+}

contrib/render-plugins/example-wasm/wasm_exec.js

@@ -0,0 +1,575 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+"use strict";
+
+(() => {
+	const enosys = () => {
+		const err = new Error("not implemented");
+		err.code = "ENOSYS";
+		return err;
+	};
+
+	if (!globalThis.fs) {
+		let outputBuf = "";
+		globalThis.fs = {
+			constants: { O_WRONLY: -1, O_RDWR: -1, O_CREAT: -1, O_TRUNC: -1, O_APPEND: -1, O_EXCL: -1, O_DIRECTORY: -1 }, // unused
+			writeSync(fd, buf) {
+				outputBuf += decoder.decode(buf);
+				const nl = outputBuf.lastIndexOf("\n");
+				if (nl != -1) {
+					console.log(outputBuf.substring(0, nl));
+					outputBuf = outputBuf.substring(nl + 1);
+				}
+				return buf.length;
+			},
+			write(fd, buf, offset, length, position, callback) {
+				if (offset !== 0 || length !== buf.length || position !== null) {
+					callback(enosys());
+					return;
+				}
+				const n = this.writeSync(fd, buf);
+				callback(null, n);
+			},
+			chmod(path, mode, callback) { callback(enosys()); },
+			chown(path, uid, gid, callback) { callback(enosys()); },
+			close(fd, callback) { callback(enosys()); },
+			fchmod(fd, mode, callback) { callback(enosys()); },
+			fchown(fd, uid, gid, callback) { callback(enosys()); },
+			fstat(fd, callback) { callback(enosys()); },
+			fsync(fd, callback) { callback(null); },
+			ftruncate(fd, length, callback) { callback(enosys()); },
+			lchown(path, uid, gid, callback) { callback(enosys()); },
+			link(path, link, callback) { callback(enosys()); },
+			lstat(path, callback) { callback(enosys()); },
+			mkdir(path, perm, callback) { callback(enosys()); },
+			open(path, flags, mode, callback) { callback(enosys()); },
+			read(fd, buffer, offset, length, position, callback) { callback(enosys()); },
+			readdir(path, callback) { callback(enosys()); },
+			readlink(path, callback) { callback(enosys()); },
+			rename(from, to, callback) { callback(enosys()); },
+			rmdir(path, callback) { callback(enosys()); },
+			stat(path, callback) { callback(enosys()); },
+			symlink(path, link, callback) { callback(enosys()); },
+			truncate(path, length, callback) { callback(enosys()); },
+			unlink(path, callback) { callback(enosys()); },
+			utimes(path, atime, mtime, callback) { callback(enosys()); },
+		};
+	}
+
+	if (!globalThis.process) {
+		globalThis.process = {
+			getuid() { return -1; },
+			getgid() { return -1; },
+			geteuid() { return -1; },
+			getegid() { return -1; },
+			getgroups() { throw enosys(); },
+			pid: -1,
+			ppid: -1,
+			umask() { throw enosys(); },
+			cwd() { throw enosys(); },
+			chdir() { throw enosys(); },
+		}
+	}
+
+	if (!globalThis.path) {
+		globalThis.path = {
+			resolve(...pathSegments) {
+				return pathSegments.join("/");
+			}
+		}
+	}
+
+	if (!globalThis.crypto) {
+		throw new Error("globalThis.crypto is not available, polyfill required (crypto.getRandomValues only)");
+	}
+
+	if (!globalThis.performance) {
+		throw new Error("globalThis.performance is not available, polyfill required (performance.now only)");
+	}
+
+	if (!globalThis.TextEncoder) {
+		throw new Error("globalThis.TextEncoder is not available, polyfill required");
+	}
+
+	if (!globalThis.TextDecoder) {
+		throw new Error("globalThis.TextDecoder is not available, polyfill required");
+	}
+
+	const encoder = new TextEncoder("utf-8");
+	const decoder = new TextDecoder("utf-8");
+
+	globalThis.Go = class {
+		constructor() {
+			this.argv = ["js"];
+			this.env = {};
+			this.exit = (code) => {
+				if (code !== 0) {
+					console.warn("exit code:", code);
+				}
+			};
+			this._exitPromise = new Promise((resolve) => {
+				this._resolveExitPromise = resolve;
+			});
+			this._pendingEvent = null;
+			this._scheduledTimeouts = new Map();
+			this._nextCallbackTimeoutID = 1;
+
+			const setInt64 = (addr, v) => {
+				this.mem.setUint32(addr + 0, v, true);
+				this.mem.setUint32(addr + 4, Math.floor(v / 4294967296), true);
+			}
+
+			const setInt32 = (addr, v) => {
+				this.mem.setUint32(addr + 0, v, true);
+			}
+
+			const getInt64 = (addr) => {
+				const low = this.mem.getUint32(addr + 0, true);
+				const high = this.mem.getInt32(addr + 4, true);
+				return low + high * 4294967296;
+			}
+
+			const loadValue = (addr) => {
+				const f = this.mem.getFloat64(addr, true);
+				if (f === 0) {
+					return undefined;
+				}
+				if (!isNaN(f)) {
+					return f;
+				}
+
+				const id = this.mem.getUint32(addr, true);
+				return this._values[id];
+			}
+
+			const storeValue = (addr, v) => {
+				const nanHead = 0x7FF80000;
+
+				if (typeof v === "number" && v !== 0) {
+					if (isNaN(v)) {
+						this.mem.setUint32(addr + 4, nanHead, true);
+						this.mem.setUint32(addr, 0, true);
+						return;
+					}
+					this.mem.setFloat64(addr, v, true);
+					return;
+				}
+
+				if (v === undefined) {
+					this.mem.setFloat64(addr, 0, true);
+					return;
+				}
+
+				let id = this._ids.get(v);
+				if (id === undefined) {
+					id = this._idPool.pop();
+					if (id === undefined) {
+						id = this._values.length;
+					}
+					this._values[id] = v;
+					this._goRefCounts[id] = 0;
+					this._ids.set(v, id);
+				}
+				this._goRefCounts[id]++;
+				let typeFlag = 0;
+				switch (typeof v) {
+					case "object":
+						if (v !== null) {
+							typeFlag = 1;
+						}
+						break;
+					case "string":
+						typeFlag = 2;
+						break;
+					case "symbol":
+						typeFlag = 3;
+						break;
+					case "function":
+						typeFlag = 4;
+						break;
+				}
+				this.mem.setUint32(addr + 4, nanHead | typeFlag, true);
+				this.mem.setUint32(addr, id, true);
+			}
+
+			const loadSlice = (addr) => {
+				const array = getInt64(addr + 0);
+				const len = getInt64(addr + 8);
+				return new Uint8Array(this._inst.exports.mem.buffer, array, len);
+			}
+
+			const loadSliceOfValues = (addr) => {
+				const array = getInt64(addr + 0);
+				const len = getInt64(addr + 8);
+				const a = new Array(len);
+				for (let i = 0; i < len; i++) {
+					a[i] = loadValue(array + i * 8);
+				}
+				return a;
+			}
+
+			const loadString = (addr) => {
+				const saddr = getInt64(addr + 0);
+				const len = getInt64(addr + 8);
+				return decoder.decode(new DataView(this._inst.exports.mem.buffer, saddr, len));
+			}
+
+			const testCallExport = (a, b) => {
+				this._inst.exports.testExport0();
+				return this._inst.exports.testExport(a, b);
+			}
+
+			const timeOrigin = Date.now() - performance.now();
+			this.importObject = {
+				_gotest: {
+					add: (a, b) => a + b,
+					callExport: testCallExport,
+				},
+				gojs: {
+					// Go's SP does not change as long as no Go code is running. Some operations (e.g. calls, getters and setters)
+					// may synchronously trigger a Go event handler. This makes Go code get executed in the middle of the imported
+					// function. A goroutine can switch to a new stack if the current stack is too small (see morestack function).
+					// This changes the SP, thus we have to update the SP used by the imported function.
+
+					// func wasmExit(code int32)
+					"runtime.wasmExit": (sp) => {
+						sp >>>= 0;
+						const code = this.mem.getInt32(sp + 8, true);
+						this.exited = true;
+						delete this._inst;
+						delete this._values;
+						delete this._goRefCounts;
+						delete this._ids;
+						delete this._idPool;
+						this.exit(code);
+					},
+
+					// func wasmWrite(fd uintptr, p unsafe.Pointer, n int32)
+					"runtime.wasmWrite": (sp) => {
+						sp >>>= 0;
+						const fd = getInt64(sp + 8);
+						const p = getInt64(sp + 16);
+						const n = this.mem.getInt32(sp + 24, true);
+						fs.writeSync(fd, new Uint8Array(this._inst.exports.mem.buffer, p, n));
+					},
+
+					// func resetMemoryDataView()
+					"runtime.resetMemoryDataView": (sp) => {
+						sp >>>= 0;
+						this.mem = new DataView(this._inst.exports.mem.buffer);
+					},
+
+					// func nanotime1() int64
+					"runtime.nanotime1": (sp) => {
+						sp >>>= 0;
+						setInt64(sp + 8, (timeOrigin + performance.now()) * 1000000);
+					},
+
+					// func walltime() (sec int64, nsec int32)
+					"runtime.walltime": (sp) => {
+						sp >>>= 0;
+						const msec = (new Date).getTime();
+						setInt64(sp + 8, msec / 1000);
+						this.mem.setInt32(sp + 16, (msec % 1000) * 1000000, true);
+					},
+
+					// func scheduleTimeoutEvent(delay int64) int32
+					"runtime.scheduleTimeoutEvent": (sp) => {
+						sp >>>= 0;
+						const id = this._nextCallbackTimeoutID;
+						this._nextCallbackTimeoutID++;
+						this._scheduledTimeouts.set(id, setTimeout(
+							() => {
+								this._resume();
+								while (this._scheduledTimeouts.has(id)) {
+									// for some reason Go failed to register the timeout event, log and try again
+									// (temporary workaround for https://github.com/golang/go/issues/28975)
+									console.warn("scheduleTimeoutEvent: missed timeout event");
+									this._resume();
+								}
+							},
+							getInt64(sp + 8),
+						));
+						this.mem.setInt32(sp + 16, id, true);
+					},
+
+					// func clearTimeoutEvent(id int32)
+					"runtime.clearTimeoutEvent": (sp) => {
+						sp >>>= 0;
+						const id = this.mem.getInt32(sp + 8, true);
+						clearTimeout(this._scheduledTimeouts.get(id));
+						this._scheduledTimeouts.delete(id);
+					},
+
+					// func getRandomData(r []byte)
+					"runtime.getRandomData": (sp) => {
+						sp >>>= 0;
+						crypto.getRandomValues(loadSlice(sp + 8));
+					},
+
+					// func finalizeRef(v ref)
+					"syscall/js.finalizeRef": (sp) => {
+						sp >>>= 0;
+						const id = this.mem.getUint32(sp + 8, true);
+						this._goRefCounts[id]--;
+						if (this._goRefCounts[id] === 0) {
+							const v = this._values[id];
+							this._values[id] = null;
+							this._ids.delete(v);
+							this._idPool.push(id);
+						}
+					},
+
+					// func stringVal(value string) ref
+					"syscall/js.stringVal": (sp) => {
+						sp >>>= 0;
+						storeValue(sp + 24, loadString(sp + 8));
+					},
+
+					// func valueGet(v ref, p string) ref
+					"syscall/js.valueGet": (sp) => {
+						sp >>>= 0;
+						const result = Reflect.get(loadValue(sp + 8), loadString(sp + 16));
+						sp = this._inst.exports.getsp() >>> 0; // see comment above
+						storeValue(sp + 32, result);
+					},
+
+					// func valueSet(v ref, p string, x ref)
+					"syscall/js.valueSet": (sp) => {
+						sp >>>= 0;
+						Reflect.set(loadValue(sp + 8), loadString(sp + 16), loadValue(sp + 32));
+					},
+
+					// func valueDelete(v ref, p string)
+					"syscall/js.valueDelete": (sp) => {
+						sp >>>= 0;
+						Reflect.deleteProperty(loadValue(sp + 8), loadString(sp + 16));
+					},
+
+					// func valueIndex(v ref, i int) ref
+					"syscall/js.valueIndex": (sp) => {
+						sp >>>= 0;
+						storeValue(sp + 24, Reflect.get(loadValue(sp + 8), getInt64(sp + 16)));
+					},
+
+					// valueSetIndex(v ref, i int, x ref)
+					"syscall/js.valueSetIndex": (sp) => {
+						sp >>>= 0;
+						Reflect.set(loadValue(sp + 8), getInt64(sp + 16), loadValue(sp + 24));
+					},
+
+					// func valueCall(v ref, m string, args []ref) (ref, bool)
+					"syscall/js.valueCall": (sp) => {
+						sp >>>= 0;
+						try {
+							const v = loadValue(sp + 8);
+							const m = Reflect.get(v, loadString(sp + 16));
+							const args = loadSliceOfValues(sp + 32);
+							const result = Reflect.apply(m, v, args);
+							sp = this._inst.exports.getsp() >>> 0; // see comment above
+							storeValue(sp + 56, result);
+							this.mem.setUint8(sp + 64, 1);
+						} catch (err) {
+							sp = this._inst.exports.getsp() >>> 0; // see comment above
+							storeValue(sp + 56, err);
+							this.mem.setUint8(sp + 64, 0);
+						}
+					},
+
+					// func valueInvoke(v ref, args []ref) (ref, bool)
+					"syscall/js.valueInvoke": (sp) => {
+						sp >>>= 0;
+						try {
+							const v = loadValue(sp + 8);
+							const args = loadSliceOfValues(sp + 16);
+							const result = Reflect.apply(v, undefined, args);
+							sp = this._inst.exports.getsp() >>> 0; // see comment above
+							storeValue(sp + 40, result);
+							this.mem.setUint8(sp + 48, 1);
+						} catch (err) {
+							sp = this._inst.exports.getsp() >>> 0; // see comment above
+							storeValue(sp + 40, err);
+							this.mem.setUint8(sp + 48, 0);
+						}
+					},
+
+					// func valueNew(v ref, args []ref) (ref, bool)
+					"syscall/js.valueNew": (sp) => {
+						sp >>>= 0;
+						try {
+							const v = loadValue(sp + 8);
+							const args = loadSliceOfValues(sp + 16);
+							const result = Reflect.construct(v, args);
+							sp = this._inst.exports.getsp() >>> 0; // see comment above
+							storeValue(sp + 40, result);
+							this.mem.setUint8(sp + 48, 1);
+						} catch (err) {
+							sp = this._inst.exports.getsp() >>> 0; // see comment above
+							storeValue(sp + 40, err);
+							this.mem.setUint8(sp + 48, 0);
+						}
+					},
+
+					// func valueLength(v ref) int
+					"syscall/js.valueLength": (sp) => {
+						sp >>>= 0;
+						setInt64(sp + 16, parseInt(loadValue(sp + 8).length));
+					},
+
+					// valuePrepareString(v ref) (ref, int)
+					"syscall/js.valuePrepareString": (sp) => {
+						sp >>>= 0;
+						const str = encoder.encode(String(loadValue(sp + 8)));
+						storeValue(sp + 16, str);
+						setInt64(sp + 24, str.length);
+					},
+
+					// valueLoadString(v ref, b []byte)
+					"syscall/js.valueLoadString": (sp) => {
+						sp >>>= 0;
+						const str = loadValue(sp + 8);
+						loadSlice(sp + 16).set(str);
+					},
+
+					// func valueInstanceOf(v ref, t ref) bool
+					"syscall/js.valueInstanceOf": (sp) => {
+						sp >>>= 0;
+						this.mem.setUint8(sp + 24, (loadValue(sp + 8) instanceof loadValue(sp + 16)) ? 1 : 0);
+					},
+
+					// func copyBytesToGo(dst []byte, src ref) (int, bool)
+					"syscall/js.copyBytesToGo": (sp) => {
+						sp >>>= 0;
+						const dst = loadSlice(sp + 8);
+						const src = loadValue(sp + 32);
+						if (!(src instanceof Uint8Array || src instanceof Uint8ClampedArray)) {
+							this.mem.setUint8(sp + 48, 0);
+							return;
+						}
+						const toCopy = src.subarray(0, dst.length);
+						dst.set(toCopy);
+						setInt64(sp + 40, toCopy.length);
+						this.mem.setUint8(sp + 48, 1);
+					},
+
+					// func copyBytesToJS(dst ref, src []byte) (int, bool)
+					"syscall/js.copyBytesToJS": (sp) => {
+						sp >>>= 0;
+						const dst = loadValue(sp + 8);
+						const src = loadSlice(sp + 16);
+						if (!(dst instanceof Uint8Array || dst instanceof Uint8ClampedArray)) {
+							this.mem.setUint8(sp + 48, 0);
+							return;
+						}
+						const toCopy = src.subarray(0, dst.length);
+						dst.set(toCopy);
+						setInt64(sp + 40, toCopy.length);
+						this.mem.setUint8(sp + 48, 1);
+					},
+
+					"debug": (value) => {
+						console.log(value);
+					},
+				}
+			};
+		}
+
+		async run(instance) {
+			if (!(instance instanceof WebAssembly.Instance)) {
+				throw new Error("Go.run: WebAssembly.Instance expected");
+			}
+			this._inst = instance;
+			this.mem = new DataView(this._inst.exports.mem.buffer);
+			this._values = [ // JS values that Go currently has references to, indexed by reference id
+				NaN,
+				0,
+				null,
+				true,
+				false,
+				globalThis,
+				this,
+			];
+			this._goRefCounts = new Array(this._values.length).fill(Infinity); // number of references that Go has to a JS value, indexed by reference id
+			this._ids = new Map([ // mapping from JS values to reference ids
+				[0, 1],
+				[null, 2],
+				[true, 3],
+				[false, 4],
+				[globalThis, 5],
+				[this, 6],
+			]);
+			this._idPool = [];   // unused ids that have been garbage collected
+			this.exited = false; // whether the Go program has exited
+
+			// Pass command line arguments and environment variables to WebAssembly by writing them to the linear memory.
+			let offset = 4096;
+
+			const strPtr = (str) => {
+				const ptr = offset;
+				const bytes = encoder.encode(str + "\0");
+				new Uint8Array(this.mem.buffer, offset, bytes.length).set(bytes);
+				offset += bytes.length;
+				if (offset % 8 !== 0) {
+					offset += 8 - (offset % 8);
+				}
+				return ptr;
+			};
+
+			const argc = this.argv.length;
+
+			const argvPtrs = [];
+			this.argv.forEach((arg) => {
+				argvPtrs.push(strPtr(arg));
+			});
+			argvPtrs.push(0);
+
+			const keys = Object.keys(this.env).sort();
+			keys.forEach((key) => {
+				argvPtrs.push(strPtr(`${key}=${this.env[key]}`));
+			});
+			argvPtrs.push(0);
+
+			const argv = offset;
+			argvPtrs.forEach((ptr) => {
+				this.mem.setUint32(offset, ptr, true);
+				this.mem.setUint32(offset + 4, 0, true);
+				offset += 8;
+			});
+
+			// The linker guarantees global data starts from at least wasmMinDataAddr.
+			// Keep in sync with cmd/link/internal/ld/data.go:wasmMinDataAddr.
+			const wasmMinDataAddr = 4096 + 8192;
+			if (offset >= wasmMinDataAddr) {
+				throw new Error("total length of command line and environment variables exceeds limit");
+			}
+
+			this._inst.exports.run(argc, argv);
+			if (this.exited) {
+				this._resolveExitPromise();
+			}
+			await this._exitPromise;
+		}
+
+		_resume() {
+			if (this.exited) {
+				throw new Error("Go program has already exited");
+			}
+			this._inst.exports.resume();
+			if (this.exited) {
+				this._resolveExitPromise();
+			}
+		}
+
+		_makeFuncWrapper(id) {
+			const go = this;
+			return function () {
+				const event = { id: id, this: this, args: arguments };
+				go._pendingEvent = event;
+				go._resume();
+				return event.result;
+			};
+		}
+	}
+})();

contrib/render-plugins/example/README.md

@@ -0,0 +1,30 @@
+# Example Frontend Render Plugin
+
+This directory contains a minimal render plugin that highlights `.txt` files
+with a custom color scheme. Use it as a starting point for your own plugins or
+as a quick way to validate the dynamic plugin system locally.
+
+## Files
+
+- `manifest.json` — metadata (including the required `schemaVersion`) consumed by Gitea when installing a plugin
+- `render.js` — an ES module that exports a `render(container, fileUrl)`
+  function; it downloads the source file and renders it in a styled `<pre>`
+
+## Build & Install
+
+1. Create a zip archive that contains both files:
+
+   ```bash
+   cd contrib/render-plugins/example
+   zip -r ../example-highlight-txt.zip manifest.json render.js
+   ```
+
+2. In the Gitea web UI, visit `Site Administration → Render Plugins`, upload
+   `example-highlight-txt.zip`, and enable it.
+
+3. Open any `.txt` file in a repository; the viewer will display the content in
+   the custom colors to confirm the plugin is active.
+
+Feel free to modify `render.js` to experiment with the API. The plugin runs in
+the browser, so only standard Web APIs are available (no bundler is required
+as long as the file stays a plain ES module).

contrib/render-plugins/example/manifest.json

@@ -0,0 +1,9 @@
+{
+  "schemaVersion": 1,
+  "id": "example-highlight-txt",
+  "name": "Example TXT Highlighter",
+  "version": "1.0.0",
+  "description": "Simple sample plugin that renders .txt files with a custom color scheme.",
+  "entry": "render.js",
+  "filePatterns": ["*.txt"]
+}

contrib/render-plugins/example/render.js

@@ -0,0 +1,28 @@
+const TEXT_COLOR = '#f6e05e';
+const BACKGROUND_COLOR = '#1a202c';
+
+async function render(container, fileUrl) {
+  container.innerHTML = '';
+
+  const message = document.createElement('div');
+  message.className = 'ui tiny message';
+  message.textContent = 'Rendered by example-highlight-txt plugin';
+  container.append(message);
+
+  const response = await fetch(fileUrl);
+  if (!response.ok) {
+    throw new Error(`Failed to download file (${response.status})`);
+  }
+  const text = await response.text();
+
+  const pre = document.createElement('pre');
+  pre.style.backgroundColor = BACKGROUND_COLOR;
+  pre.style.color = TEXT_COLOR;
+  pre.style.padding = '1rem';
+  pre.style.borderRadius = '0.5rem';
+  pre.style.overflow = 'auto';
+  pre.textContent = text;
+  container.append(pre);
+}
+
+export default {render};

models/migrations/migrations.go

@@ -398,6 +398,7 @@ func prepareMigrationTasks() []*migration {
 		// Gitea 1.25.0 ends at migration ID number 322 (database version 323)
 
 		newMigration(323, "Add support for actions concurrency", v1_26.AddActionsConcurrency),
+		newMigration(324, "Add frontend render plugin table", v1_26.AddRenderPluginTable),
 	}
 	return preparedMigrations
 }

models/migrations/v1_26/v324.go

@@ -0,0 +1,30 @@
+// Copyright 2025 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package v1_26
+
+import (
+	"code.gitea.io/gitea/modules/timeutil"
+
+	"xorm.io/xorm"
+)
+
+// AddRenderPluginTable creates the render_plugin table used by the frontend plugin system.
+func AddRenderPluginTable(x *xorm.Engine) error {
+	type RenderPlugin struct {
+		ID            int64              `xorm:"pk autoincr"`
+		Identifier    string             `xorm:"UNIQUE NOT NULL"`
+		Name          string             `xorm:"NOT NULL"`
+		Version       string             `xorm:"NOT NULL"`
+		Description   string             `xorm:"TEXT"`
+		Source        string             `xorm:"TEXT"`
+		Entry         string             `xorm:"NOT NULL"`
+		FilePatterns  []string           `xorm:"JSON"`
+		FormatVersion int                `xorm:"NOT NULL DEFAULT 1"`
+		Enabled       bool               `xorm:"NOT NULL DEFAULT false"`
+		CreatedUnix   timeutil.TimeStamp `xorm:"created NOT NULL"`
+		UpdatedUnix   timeutil.TimeStamp `xorm:"updated NOT NULL"`
+	}
+
+	return x.Sync(new(RenderPlugin))
+}

models/render/plugin.go

@@ -0,0 +1,125 @@
+// Copyright 2025 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package render
+
+import (
+	"context"
+
+	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/modules/timeutil"
+)
+
+// Plugin represents a frontend render plugin installed on the instance.
+type Plugin struct {
+	ID            int64              `xorm:"pk autoincr"`
+	Identifier    string             `xorm:"UNIQUE NOT NULL"`
+	Name          string             `xorm:"NOT NULL"`
+	Version       string             `xorm:"NOT NULL"`
+	Description   string             `xorm:"TEXT"`
+	Source        string             `xorm:"TEXT"`
+	Entry         string             `xorm:"NOT NULL"`
+	FilePatterns  []string           `xorm:"JSON"`
+	FormatVersion int                `xorm:"NOT NULL DEFAULT 1"`
+	Enabled       bool               `xorm:"NOT NULL DEFAULT false"`
+	CreatedUnix   timeutil.TimeStamp `xorm:"created NOT NULL"`
+	UpdatedUnix   timeutil.TimeStamp `xorm:"updated NOT NULL"`
+}
+
+func init() {
+	db.RegisterModel(new(Plugin))
+}
+
+// TableName implements xorm's table name convention.
+func (Plugin) TableName() string {
+	return "render_plugin"
+}
+
+// ListPlugins returns all registered render plugins ordered by identifier.
+func ListPlugins(ctx context.Context) ([]*Plugin, error) {
+	plugins := make([]*Plugin, 0, 4)
+	return plugins, db.GetEngine(ctx).Asc("identifier").Find(&plugins)
+}
+
+// ListEnabledPlugins returns all enabled render plugins.
+func ListEnabledPlugins(ctx context.Context) ([]*Plugin, error) {
+	plugins := make([]*Plugin, 0, 4)
+	return plugins, db.GetEngine(ctx).
+		Where("enabled = ?", true).
+		Asc("identifier").
+		Find(&plugins)
+}
+
+// GetPluginByID returns the plugin with the given primary key.
+func GetPluginByID(ctx context.Context, id int64) (*Plugin, error) {
+	plug := new(Plugin)
+	has, err := db.GetEngine(ctx).ID(id).Get(plug)
+	if err != nil {
+		return nil, err
+	}
+	if !has {
+		return nil, db.ErrNotExist{ID: id}
+	}
+	return plug, nil
+}
+
+// GetPluginByIdentifier returns the plugin with the given identifier.
+func GetPluginByIdentifier(ctx context.Context, identifier string) (*Plugin, error) {
+	plug := new(Plugin)
+	has, err := db.GetEngine(ctx).
+		Where("identifier = ?", identifier).
+		Get(plug)
+	if err != nil {
+		return nil, err
+	}
+	if !has {
+		return nil, db.ErrNotExist{Resource: identifier}
+	}
+	return plug, nil
+}
+
+// UpsertPlugin inserts or updates the plugin identified by Identifier.
+func UpsertPlugin(ctx context.Context, plug *Plugin) error {
+	return db.WithTx(ctx, func(ctx context.Context) error {
+		existing := new(Plugin)
+		has, err := db.GetEngine(ctx).
+			Where("identifier = ?", plug.Identifier).
+			Get(existing)
+		if err != nil {
+			return err
+		}
+		if has {
+			plug.ID = existing.ID
+			plug.Enabled = existing.Enabled
+			plug.CreatedUnix = existing.CreatedUnix
+			_, err = db.GetEngine(ctx).
+				ID(existing.ID).
+				AllCols().
+				Update(plug)
+			return err
+		}
+		_, err = db.GetEngine(ctx).Insert(plug)
+		return err
+	})
+}
+
+// SetPluginEnabled toggles plugin enabled state.
+func SetPluginEnabled(ctx context.Context, plug *Plugin, enabled bool) error {
+	if plug.Enabled == enabled {
+		return nil
+	}
+	plug.Enabled = enabled
+	_, err := db.GetEngine(ctx).
+		ID(plug.ID).
+		Cols("enabled").
+		Update(plug)
+	return err
+}
+
+// DeletePlugin removes the plugin row.
+func DeletePlugin(ctx context.Context, plug *Plugin) error {
+	_, err := db.GetEngine(ctx).
+		ID(plug.ID).
+		Delete(new(Plugin))
+	return err
+}

modules/renderplugin/manifest.go

@@ -0,0 +1,105 @@
+// Copyright 2025 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package renderplugin
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"regexp"
+	"sort"
+	"strings"
+
+	"code.gitea.io/gitea/modules/util"
+)
+
+var identifierRegexp = regexp.MustCompile(`^[a-z0-9][a-z0-9\-_.]{1,63}$`)
+
+// Manifest describes the metadata declared by a render plugin.
+const SupportedManifestVersion = 1
+
+type Manifest struct {
+	SchemaVersion int      `json:"schemaVersion"`
+	ID            string   `json:"id"`
+	Name          string   `json:"name"`
+	Version       string   `json:"version"`
+	Description   string   `json:"description"`
+	Entry         string   `json:"entry"`
+	FilePatterns  []string `json:"filePatterns"`
+}
+
+// Normalize validates mandatory fields and normalizes values.
+func (m *Manifest) Normalize() error {
+	if m.SchemaVersion == 0 {
+		return fmt.Errorf("manifest schemaVersion is required")
+	}
+	if m.SchemaVersion != SupportedManifestVersion {
+		return fmt.Errorf("manifest schemaVersion %d is not supported", m.SchemaVersion)
+	}
+	m.ID = strings.TrimSpace(strings.ToLower(m.ID))
+	if !identifierRegexp.MatchString(m.ID) {
+		return fmt.Errorf("manifest id %q is invalid; only lowercase letters, numbers, dash, underscore and dot are allowed", m.ID)
+	}
+	m.Name = strings.TrimSpace(m.Name)
+	if m.Name == "" {
+		return fmt.Errorf("manifest name is required")
+	}
+	m.Version = strings.TrimSpace(m.Version)
+	if m.Version == "" {
+		return fmt.Errorf("manifest version is required")
+	}
+	if m.Entry == "" {
+		m.Entry = "render.js"
+	}
+	m.Entry = util.PathJoinRelX(m.Entry)
+	if m.Entry == "" || strings.HasPrefix(m.Entry, "../") {
+		return fmt.Errorf("manifest entry %q is invalid", m.Entry)
+	}
+	cleanPatterns := make([]string, 0, len(m.FilePatterns))
+	for _, pattern := range m.FilePatterns {
+		pattern = strings.TrimSpace(pattern)
+		if pattern == "" {
+			continue
+		}
+		cleanPatterns = append(cleanPatterns, pattern)
+	}
+	if len(cleanPatterns) == 0 {
+		return fmt.Errorf("manifest must declare at least one file pattern")
+	}
+	sort.Strings(cleanPatterns)
+	m.FilePatterns = cleanPatterns
+	return nil
+}
+
+// LoadManifest reads and validates the manifest.json file located under dir.
+func LoadManifest(dir string) (*Manifest, error) {
+	manifestPath := filepath.Join(dir, "manifest.json")
+	f, err := os.Open(manifestPath)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+	var manifest Manifest
+	if err := json.NewDecoder(f).Decode(&manifest); err != nil {
+		return nil, fmt.Errorf("malformed manifest.json: %w", err)
+	}
+	if err := manifest.Normalize(); err != nil {
+		return nil, err
+	}
+	return &manifest, nil
+}
+
+// Metadata is the public information exposed to the frontend for an enabled plugin.
+type Metadata struct {
+	ID           string   `json:"id"`
+	Name         string   `json:"name"`
+	Version      string   `json:"version"`
+	Description  string   `json:"description"`
+	Entry        string   `json:"entry"`
+	EntryURL     string   `json:"entryUrl"`
+	AssetsBase   string   `json:"assetsBaseUrl"`
+	FilePatterns []string `json:"filePatterns"`
+	SchemaVersion int     `json:"schemaVersion"`
+}

modules/renderplugin/path.go

@@ -0,0 +1,32 @@
+// Copyright 2025 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package renderplugin
+
+import (
+	"path"
+
+	"code.gitea.io/gitea/modules/storage"
+)
+
+// Storage returns the object storage used for render plugins.
+func Storage() storage.ObjectStorage {
+	return storage.RenderPlugins
+}
+
+// ObjectPath builds a storage-relative path for a plugin asset.
+func ObjectPath(identifier string, elems ...string) string {
+	joined := path.Join(elems...)
+	if joined == "." || joined == "" {
+		return path.Join(identifier)
+	}
+	return path.Join(identifier, joined)
+}
+
+// ObjectPrefix returns the storage prefix for a plugin identifier.
+func ObjectPrefix(identifier string) string {
+	if identifier == "" {
+		return ""
+	}
+	return identifier + "/"
+}

modules/setting/render_plugin.go

@@ -0,0 +1,16 @@
+// Copyright 2025 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package setting
+
+type RenderPluginSetting struct {
+	Storage *Storage
+}
+
+var RenderPlugin RenderPluginSetting
+
+func loadRenderPluginFrom(rootCfg ConfigProvider) (err error) {
+	sec, _ := rootCfg.GetSection("render_plugins")
+	RenderPlugin.Storage, err = getStorage(rootCfg, "render-plugins", "", sec)
+	return err
+}

modules/setting/setting.go

@@ -138,6 +138,9 @@ func loadCommonSettingsFrom(cfg ConfigProvider) error {
 	if err := loadActionsFrom(cfg); err != nil {
 		return err
 	}
+	if err := loadRenderPluginFrom(cfg); err != nil {
+		return err
+	}
 	loadUIFrom(cfg)
 	loadAdminFrom(cfg)
 	loadAPIFrom(cfg)

modules/storage/storage.go

@@ -133,6 +133,9 @@ var (
 	Actions ObjectStorage = uninitializedStorage
 	// Actions Artifacts represents actions artifacts storage
 	ActionsArtifacts ObjectStorage = uninitializedStorage
+
+	// RenderPlugins represents render plugin storage
+	RenderPlugins ObjectStorage = uninitializedStorage
 )
 
 // Init init the storage
@@ -145,6 +148,7 @@ func Init() error {
 		initRepoArchives,
 		initPackages,
 		initActions,
+		initRenderPlugins,
 	} {
 		if err := f(); err != nil {
 			return err
@@ -228,3 +232,9 @@ func initActions() (err error) {
 	ActionsArtifacts, err = NewStorage(setting.Actions.ArtifactStorage.Type, setting.Actions.ArtifactStorage)
 	return err
 }
+
+func initRenderPlugins() (err error) {
+	log.Info("Initialising Render Plugin storage with type: %s", setting.RenderPlugin.Storage.Type)
+	RenderPlugins, err = NewStorage(setting.RenderPlugin.Storage.Type, setting.RenderPlugin.Storage)
+	return err
+}

options/locale/locale_en-US.ini

@@ -2991,6 +2991,45 @@ users = User Accounts
 organizations = Organizations
 assets = Code Assets
 repositories = Repositories
+render_plugins = Render Plugins
+render_plugins.description = Upload, enable, or disable frontend renderers provided as plugins.
+render_plugins.upload_label = Plugin Archive (.zip)
+render_plugins.install = Install Plugin
+render_plugins.example_hint = Example source files are available in contrib/render-plugins/example (zip both files and upload the archive here).
+render_plugins.table.name = Name
+render_plugins.table.identifier = Identifier
+render_plugins.table.version = Version
+render_plugins.table.patterns = File Patterns
+render_plugins.table.status = Status
+render_plugins.table.actions = Actions
+render_plugins.empty = No render plugins are installed yet.
+render_plugins.enable = Enable
+render_plugins.disable = Disable
+render_plugins.delete = Delete
+render_plugins.delete_confirm = Delete plugin "%s"? All of its files will be removed.
+render_plugins.status.enabled = Enabled
+render_plugins.status.disabled = Disabled
+render_plugins.upload_success = Plugin "%s" installed successfully.
+render_plugins.upload_failed = Failed to install plugin: %v
+render_plugins.upload_missing = Please choose a plugin archive to upload.
+render_plugins.enabled = Plugin "%s" enabled.
+render_plugins.disabled = Plugin "%s" disabled.
+render_plugins.deleted = Plugin "%s" deleted.
+render_plugins.invalid = Unknown plugin request.
+render_plugins.upgrade = Upgrade
+render_plugins.upgrade_success = Plugin "%s" upgraded to version %s.
+render_plugins.upgrade_failed = Failed to upgrade plugin: %v
+render_plugins.back_to_list = Back to plugin list
+render_plugins.detail_title = Plugin: %s
+render_plugins.detail.description = Description
+render_plugins.detail.description_empty = No description provided.
+render_plugins.detail.format_version = Manifest format version
+render_plugins.detail.entry = Entry file
+render_plugins.detail.source = Source
+render_plugins.detail.none = Not provided
+render_plugins.detail.file_patterns_empty = No file patterns declared.
+render_plugins.detail.actions = Plugin actions
+render_plugins.detail.upgrade = Upgrade plugin
 hooks = Webhooks
 integrations = Integrations
 authentication = Authentication Sources

routers/web/admin/render_plugins.go

@@ -0,0 +1,165 @@
+// Copyright 2025 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package admin
+
+import (
+	"fmt"
+	"net/http"
+	"strings"
+
+	render_model "code.gitea.io/gitea/models/render"
+	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/templates"
+	"code.gitea.io/gitea/services/context"
+	plugin_service "code.gitea.io/gitea/services/renderplugin"
+)
+
+const (
+	tplRenderPlugins      templates.TplName = "admin/render/plugins"
+	tplRenderPluginDetail templates.TplName = "admin/render/plugin_detail"
+)
+
+// RenderPlugins shows the plugin management page.
+func RenderPlugins(ctx *context.Context) {
+	plugs, err := render_model.ListPlugins(ctx)
+	if err != nil {
+		ctx.ServerError("ListPlugins", err)
+		return
+	}
+	ctx.Data["Title"] = ctx.Tr("admin.render_plugins")
+	ctx.Data["PageIsAdminRenderPlugins"] = true
+	ctx.Data["Plugins"] = plugs
+	ctx.HTML(http.StatusOK, tplRenderPlugins)
+}
+
+// RenderPluginDetail shows a single plugin detail page.
+func RenderPluginDetail(ctx *context.Context) {
+	plug := mustGetRenderPlugin(ctx)
+	if plug == nil {
+		return
+	}
+	ctx.Data["Title"] = ctx.Tr("admin.render_plugins.detail_title", plug.Name)
+	ctx.Data["PageIsAdminRenderPlugins"] = true
+	ctx.Data["Plugin"] = plug
+	ctx.HTML(http.StatusOK, tplRenderPluginDetail)
+}
+
+// RenderPluginsUpload handles plugin uploads.
+func RenderPluginsUpload(ctx *context.Context) {
+	file, header, err := ctx.Req.FormFile("plugin")
+	if err != nil {
+		ctx.Flash.Error(ctx.Tr("admin.render_plugins.upload_failed", err))
+		redirectRenderPlugins(ctx)
+		return
+	}
+	defer file.Close()
+	if header.Size == 0 {
+		ctx.Flash.Error(ctx.Tr("admin.render_plugins.upload_missing"))
+		redirectRenderPlugins(ctx)
+		return
+	}
+	if _, err := plugin_service.InstallFromArchive(ctx, file, header.Filename, ""); err != nil {
+		ctx.Flash.Error(ctx.Tr("admin.render_plugins.upload_failed", err))
+	} else {
+		ctx.Flash.Success(ctx.Tr("admin.render_plugins.upload_success", header.Filename))
+	}
+	redirectRenderPlugins(ctx)
+}
+
+// RenderPluginsEnable toggles plugin state to enabled.
+func RenderPluginsEnable(ctx *context.Context) {
+	plug := mustGetRenderPlugin(ctx)
+	if plug == nil {
+		return
+	}
+	if err := plugin_service.SetEnabled(ctx, plug, true); err != nil {
+		ctx.Flash.Error(err.Error())
+	} else {
+		ctx.Flash.Success(ctx.Tr("admin.render_plugins.enabled", plug.Name))
+	}
+	redirectRenderPlugins(ctx)
+}
+
+// RenderPluginsDisable toggles plugin state to disabled.
+func RenderPluginsDisable(ctx *context.Context) {
+	plug := mustGetRenderPlugin(ctx)
+	if plug == nil {
+		return
+	}
+	if err := plugin_service.SetEnabled(ctx, plug, false); err != nil {
+		ctx.Flash.Error(err.Error())
+	} else {
+		ctx.Flash.Success(ctx.Tr("admin.render_plugins.disabled", plug.Name))
+	}
+	redirectRenderPlugins(ctx)
+}
+
+// RenderPluginsDelete removes a plugin entirely.
+func RenderPluginsDelete(ctx *context.Context) {
+	plug := mustGetRenderPlugin(ctx)
+	if plug == nil {
+		return
+	}
+	if err := plugin_service.Delete(ctx, plug); err != nil {
+		ctx.Flash.Error(err.Error())
+	} else {
+		ctx.Flash.Success(ctx.Tr("admin.render_plugins.deleted", plug.Name))
+	}
+	redirectRenderPlugins(ctx)
+}
+
+// RenderPluginsUpgrade upgrades an existing plugin with a new archive.
+func RenderPluginsUpgrade(ctx *context.Context) {
+	plug := mustGetRenderPlugin(ctx)
+	if plug == nil {
+		return
+	}
+	file, header, err := ctx.Req.FormFile("plugin")
+	if err != nil {
+		ctx.Flash.Error(ctx.Tr("admin.render_plugins.upgrade_failed", err))
+		redirectRenderPlugins(ctx)
+		return
+	}
+	defer file.Close()
+	if header.Size == 0 {
+		ctx.Flash.Error(ctx.Tr("admin.render_plugins.upload_missing"))
+		redirectRenderPlugins(ctx)
+		return
+	}
+	updated, err := plugin_service.InstallFromArchive(ctx, file, header.Filename, plug.Identifier)
+	if err != nil {
+		ctx.Flash.Error(ctx.Tr("admin.render_plugins.upgrade_failed", err))
+	} else {
+		ctx.Flash.Success(ctx.Tr("admin.render_plugins.upgrade_success", updated.Name, updated.Version))
+	}
+	redirectRenderPlugins(ctx)
+}
+
+func mustGetRenderPlugin(ctx *context.Context) *render_model.Plugin {
+	id := ctx.PathParamInt64("id")
+	if id <= 0 {
+		ctx.Flash.Error(ctx.Tr("admin.render_plugins.invalid"))
+		redirectRenderPlugins(ctx)
+		return nil
+	}
+	plug, err := render_model.GetPluginByID(ctx, id)
+	if err != nil {
+		ctx.Flash.Error(fmt.Sprintf("%v", err))
+		redirectRenderPlugins(ctx)
+		return nil
+	}
+	return plug
+}
+
+func redirectRenderPlugins(ctx *context.Context) {
+	redirectTo := ctx.FormString("redirect_to")
+	if redirectTo != "" {
+		base := setting.AppSubURL + "/"
+		if strings.HasPrefix(redirectTo, base) {
+			ctx.Redirect(redirectTo)
+			return
+		}
+	}
+	ctx.Redirect(setting.AppSubURL + "/-/admin/render-plugins")
+}

routers/web/renderplugin/assets.go

@@ -0,0 +1,93 @@
+// Copyright 2025 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package renderplugin
+
+import (
+	"encoding/json"
+	"net/http"
+	"os"
+	"path"
+	"strings"
+
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/renderplugin"
+	"code.gitea.io/gitea/modules/setting"
+	plugin_service "code.gitea.io/gitea/services/renderplugin"
+)
+
+// AssetsHandler returns an http.Handler that serves plugin metadata and static files.
+func AssetsHandler() http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodGet && r.Method != http.MethodHead {
+			w.WriteHeader(http.StatusMethodNotAllowed)
+			return
+		}
+		prefix := setting.AppSubURL + "/assets/render-plugins/"
+		if !strings.HasPrefix(r.URL.Path, prefix) {
+			w.WriteHeader(http.StatusNotFound)
+			return
+		}
+		rel := strings.TrimPrefix(r.URL.Path, prefix)
+		rel = strings.TrimLeft(rel, "/")
+		if rel == "" {
+			w.WriteHeader(http.StatusNotFound)
+			return
+		}
+		if rel == "index.json" {
+			serveMetadata(w, r)
+			return
+		}
+		parts := strings.SplitN(rel, "/", 2)
+		if len(parts) != 2 {
+			w.WriteHeader(http.StatusNotFound)
+			return
+		}
+		clean := path.Clean("/" + parts[1])
+		if clean == "/" {
+			w.WriteHeader(http.StatusNotFound)
+			return
+		}
+		clean = strings.TrimPrefix(clean, "/")
+		if strings.HasPrefix(clean, "../") {
+			w.WriteHeader(http.StatusNotFound)
+			return
+		}
+		objectPath := renderplugin.ObjectPath(parts[0], clean)
+		obj, err := renderplugin.Storage().Open(objectPath)
+		if err != nil {
+			if os.IsNotExist(err) {
+				w.WriteHeader(http.StatusNotFound)
+			} else {
+				log.Error("Unable to open render plugin asset %s: %v", objectPath, err)
+				w.WriteHeader(http.StatusInternalServerError)
+			}
+			return
+		}
+		defer obj.Close()
+		info, err := obj.Stat()
+		if err != nil {
+			log.Error("Unable to stat render plugin asset %s: %v", objectPath, err)
+			w.WriteHeader(http.StatusInternalServerError)
+			return
+		}
+		http.ServeContent(w, r, path.Base(clean), info.ModTime(), obj)
+	})
+}
+
+func serveMetadata(w http.ResponseWriter, r *http.Request) {
+	meta, err := plugin_service.BuildMetadata(r.Context())
+	if err != nil {
+		log.Error("Unable to build render plugin metadata: %v", err)
+		w.WriteHeader(http.StatusInternalServerError)
+		return
+	}
+	w.Header().Set("Content-Type", "application/json")
+	if r.Method == http.MethodHead {
+		w.WriteHeader(http.StatusOK)
+		return
+	}
+	if err := json.NewEncoder(w).Encode(meta); err != nil {
+		log.Error("Failed to encode render plugin metadata: %v", err)
+	}
+}

routers/web/repo/view_file.go

@@ -5,6 +5,7 @@ package repo
 
 import (
 	"bytes"
+	"encoding/base64"
 	"fmt"
 	"image"
 	"io"
@@ -228,6 +229,14 @@ func prepareFileView(ctx *context.Context, entry *git.TreeEntry) {
 	ctx.Data["IsRepresentableAsText"] = fInfo.st.IsRepresentableAsText()
 	ctx.Data["IsExecutable"] = entry.IsExecutable()
 	ctx.Data["CanCopyContent"] = fInfo.st.IsRepresentableAsText() || fInfo.st.IsImage()
+	ctx.Data["RenderFileMimeType"] = fInfo.st.GetMimeType()
+	if len(buf) > 0 {
+		chunk := buf
+		if len(chunk) > typesniffer.SniffContentSize {
+			chunk = chunk[:typesniffer.SniffContentSize]
+		}
+		ctx.Data["RenderFileHeadChunk"] = base64.StdEncoding.EncodeToString(chunk)
+	}
 
 	attrs, ok := prepareFileViewLfsAttrs(ctx)
 	if !ok {

routers/web/web.go

@@ -34,6 +34,7 @@ import (
 	"code.gitea.io/gitea/routers/web/misc"
 	"code.gitea.io/gitea/routers/web/org"
 	org_setting "code.gitea.io/gitea/routers/web/org/setting"
+	"code.gitea.io/gitea/routers/web/renderplugin"
 	"code.gitea.io/gitea/routers/web/repo"
 	"code.gitea.io/gitea/routers/web/repo/actions"
 	repo_setting "code.gitea.io/gitea/routers/web/repo/setting"
@@ -232,6 +233,7 @@ func Routes() *web.Router {
 	routes := web.NewRouter()
 
 	routes.Head("/", misc.DummyOK) // for health check - doesn't need to be passed through gzip handler
+	routes.Methods("GET, HEAD, OPTIONS", "/assets/render-plugins/*", optionsCorsHandler(), renderplugin.AssetsHandler())
 	routes.Methods("GET, HEAD, OPTIONS", "/assets/*", optionsCorsHandler(), public.FileHandlerFunc())
 	routes.Methods("GET, HEAD", "/avatars/*", avatarStorageHandler(setting.Avatar.Storage, "avatars", storage.Avatars))
 	routes.Methods("GET, HEAD", "/repo-avatars/*", avatarStorageHandler(setting.RepoAvatar.Storage, "repo-avatars", storage.RepoAvatars))
@@ -772,6 +774,16 @@ func registerWebRoutes(m *web.Router) {
 			m.Post("/cleanup", admin.CleanupExpiredData)
 		}, packagesEnabled)
 
+		m.Group("/render-plugins", func() {
+			m.Get("", admin.RenderPlugins)
+			m.Get("/{id}", admin.RenderPluginDetail)
+			m.Post("/upload", admin.RenderPluginsUpload)
+			m.Post("/{id}/enable", admin.RenderPluginsEnable)
+			m.Post("/{id}/disable", admin.RenderPluginsDisable)
+			m.Post("/{id}/delete", admin.RenderPluginsDelete)
+			m.Post("/{id}/upgrade", admin.RenderPluginsUpgrade)
+		})
+
 		m.Group("/hooks", func() {
 			m.Get("", admin.DefaultOrSystemWebhooks)
 			m.Post("/delete", admin.DeleteDefaultOrSystemWebhook)

services/renderplugin/service.go

@@ -0,0 +1,283 @@
+// Copyright 2025 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package renderplugin
+
+import (
+	"archive/zip"
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"strings"
+
+	render_model "code.gitea.io/gitea/models/render"
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/renderplugin"
+	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/storage"
+	"code.gitea.io/gitea/modules/util"
+)
+
+var errManifestNotFound = errors.New("manifest.json not found in plugin archive")
+
+// InstallFromArchive installs or upgrades a plugin from an uploaded ZIP archive.
+// If expectedIdentifier is non-empty the archive must contain the matching plugin id.
+func InstallFromArchive(ctx context.Context, upload io.Reader, filename, expectedIdentifier string) (*render_model.Plugin, error) {
+	tmpFile, cleanupFile, err := setting.AppDataTempDir("render-plugins").CreateTempFileRandom("upload", "*.zip")
+	if err != nil {
+		return nil, err
+	}
+	defer cleanupFile()
+	if _, err := io.Copy(tmpFile, upload); err != nil {
+		return nil, err
+	}
+	if err := tmpFile.Close(); err != nil {
+		return nil, err
+	}
+
+	pluginDir, manifest, cleanupDir, err := extractArchive(tmpFile.Name())
+	if err != nil {
+		return nil, err
+	}
+	defer cleanupDir()
+	if expectedIdentifier != "" && manifest.ID != expectedIdentifier {
+		return nil, fmt.Errorf("uploaded plugin id %s does not match %s", manifest.ID, expectedIdentifier)
+	}
+
+	entryPath := filepath.Join(pluginDir, filepath.FromSlash(manifest.Entry))
+	if ok, _ := util.IsExist(entryPath); !ok {
+		return nil, fmt.Errorf("plugin entry %s not found", manifest.Entry)
+	}
+	if err := replacePluginFiles(manifest.ID, pluginDir); err != nil {
+		return nil, err
+	}
+
+	plug := &render_model.Plugin{
+		Identifier:    manifest.ID,
+		Name:          manifest.Name,
+		Version:       manifest.Version,
+		Description:   manifest.Description,
+		Source:        strings.TrimSpace(filename),
+		Entry:         manifest.Entry,
+		FilePatterns:  manifest.FilePatterns,
+		FormatVersion: manifest.SchemaVersion,
+	}
+	if err := render_model.UpsertPlugin(ctx, plug); err != nil {
+		return nil, err
+	}
+	return plug, nil
+}
+
+// Delete removes a plugin from disk and database.
+func Delete(ctx context.Context, plug *render_model.Plugin) error {
+	if err := deletePluginFiles(plug.Identifier); err != nil {
+		return err
+	}
+	return render_model.DeletePlugin(ctx, plug)
+}
+
+// SetEnabled toggles plugin availability after verifying assets exist when enabling.
+func SetEnabled(ctx context.Context, plug *render_model.Plugin, enabled bool) error {
+	if enabled {
+		if err := ensureEntryExists(plug); err != nil {
+			return err
+		}
+	}
+	return render_model.SetPluginEnabled(ctx, plug, enabled)
+}
+
+// BuildMetadata returns metadata for all enabled plugins.
+func BuildMetadata(ctx context.Context) ([]renderplugin.Metadata, error) {
+	plugs, err := render_model.ListEnabledPlugins(ctx)
+	if err != nil {
+		return nil, err
+	}
+	base := setting.AppSubURL + "/assets/render-plugins/"
+	metas := make([]renderplugin.Metadata, 0, len(plugs))
+	for _, plug := range plugs {
+		if plug.FormatVersion != renderplugin.SupportedManifestVersion {
+			log.Warn("Render plugin %s disabled due to incompatible schema version %d", plug.Identifier, plug.FormatVersion)
+			continue
+		}
+		if err := ensureEntryExists(plug); err != nil {
+			log.Error("Render plugin %s entry missing: %v", plug.Identifier, err)
+			continue
+		}
+		assetsBase := base + plug.Identifier + "/"
+		metas = append(metas, renderplugin.Metadata{
+			ID:           plug.Identifier,
+			Name:         plug.Name,
+			Version:      plug.Version,
+			Description:  plug.Description,
+			Entry:        plug.Entry,
+			EntryURL:     assetsBase + plug.Entry,
+			AssetsBase:   assetsBase,
+			FilePatterns: append([]string(nil), plug.FilePatterns...),
+			SchemaVersion: plug.FormatVersion,
+		})
+	}
+	return metas, nil
+}
+
+func ensureEntryExists(plug *render_model.Plugin) error {
+	entryPath := renderplugin.ObjectPath(plug.Identifier, filepath.ToSlash(plug.Entry))
+	if _, err := renderplugin.Storage().Stat(entryPath); err != nil {
+		return fmt.Errorf("plugin entry %s missing: %w", plug.Entry, err)
+	}
+	return nil
+}
+
+func extractArchive(zipPath string) (string, *renderplugin.Manifest, func(), error) {
+	reader, err := zip.OpenReader(zipPath)
+	if err != nil {
+		return "", nil, nil, err
+	}
+
+	extractDir, cleanup, err := setting.AppDataTempDir("render-plugins").MkdirTempRandom("extract", "*")
+	if err != nil {
+		_ = reader.Close()
+		return "", nil, nil, err
+	}
+
+	closeAll := func() {
+		_ = reader.Close()
+		cleanup()
+	}
+
+	for _, file := range reader.File {
+		if err := extractZipEntry(file, extractDir); err != nil {
+			closeAll()
+			return "", nil, nil, err
+		}
+	}
+
+	manifestPath, err := findManifest(extractDir)
+	if err != nil {
+		closeAll()
+		return "", nil, nil, err
+	}
+	manifestDir := filepath.Dir(manifestPath)
+	manifest, err := renderplugin.LoadManifest(manifestDir)
+	if err != nil {
+		closeAll()
+		return "", nil, nil, err
+	}
+
+	return manifestDir, manifest, closeAll, nil
+}
+
+func extractZipEntry(file *zip.File, dest string) error {
+	cleanRel := util.PathJoinRelX(file.Name)
+	if cleanRel == "" || cleanRel == "." {
+		return nil
+	}
+	target := filepath.Join(dest, filepath.FromSlash(cleanRel))
+	rel, err := filepath.Rel(dest, target)
+	if err != nil || strings.HasPrefix(rel, "..") {
+		return fmt.Errorf("archive path %q escapes extraction directory", file.Name)
+	}
+	if file.FileInfo().IsDir() {
+		return os.MkdirAll(target, os.ModePerm)
+	}
+	if file.FileInfo().Mode()&os.ModeSymlink != 0 {
+		return fmt.Errorf("symlinks are not supported inside plugin archives: %s", file.Name)
+	}
+	if err := os.MkdirAll(filepath.Dir(target), os.ModePerm); err != nil {
+		return err
+	}
+	rc, err := file.Open()
+	if err != nil {
+		return err
+	}
+	defer rc.Close()
+	out, err := os.OpenFile(target, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, file.Mode().Perm())
+	if err != nil {
+		return err
+	}
+	defer out.Close()
+	if _, err := io.Copy(out, rc); err != nil {
+		return err
+	}
+	return nil
+}
+
+func findManifest(root string) (string, error) {
+	var manifestPath string
+	err := filepath.WalkDir(root, func(path string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		if d.IsDir() {
+			return nil
+		}
+		if strings.EqualFold(d.Name(), "manifest.json") {
+			if manifestPath != "" {
+				return fmt.Errorf("multiple manifest.json files found")
+			}
+			manifestPath = path
+		}
+		return nil
+	})
+	if err != nil {
+		return "", err
+	}
+	if manifestPath == "" {
+		return "", errManifestNotFound
+	}
+	return manifestPath, nil
+}
+
+func replacePluginFiles(identifier, srcDir string) error {
+	if err := deletePluginFiles(identifier); err != nil {
+		return err
+	}
+	return uploadPluginDir(identifier, srcDir)
+}
+
+func deletePluginFiles(identifier string) error {
+	store := renderplugin.Storage()
+	prefix := renderplugin.ObjectPrefix(identifier)
+	return store.IterateObjects(prefix, func(path string, obj storage.Object) error {
+		_ = obj.Close()
+		return store.Delete(path)
+	})
+}
+
+func uploadPluginDir(identifier, src string) error {
+	store := renderplugin.Storage()
+	return filepath.WalkDir(src, func(path string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		if d.IsDir() {
+			return nil
+		}
+		if d.Type()&os.ModeSymlink != 0 {
+			return fmt.Errorf("symlinks are not supported inside plugin archives")
+		}
+		rel, err := filepath.Rel(src, path)
+		if err != nil {
+			return err
+		}
+		file, err := os.Open(path)
+		if err != nil {
+			return err
+		}
+		info, err := file.Stat()
+		if err != nil {
+			file.Close()
+			return err
+		}
+		objectPath := renderplugin.ObjectPath(identifier, filepath.ToSlash(rel))
+		_, err = store.Save(objectPath, file, info.Size())
+		closeErr := file.Close()
+		if err != nil {
+			return err
+		}
+		return closeErr
+	})
+}

templates/admin/navbar.tmpl

@@ -38,6 +38,9 @@
 						{{ctx.Locale.Tr "packages.title"}}
 					</a>
 				{{end}}
+				<a class="{{if .PageIsAdminRenderPlugins}}active {{end}}item" href="{{AppSubUrl}}/-/admin/render-plugins">
+					{{ctx.Locale.Tr "admin.render_plugins"}}
+				</a>
 				<a class="{{if .PageIsAdminRepositories}}active {{end}}item" href="{{AppSubUrl}}/-/admin/repos">
 					{{ctx.Locale.Tr "admin.repositories"}}
 				</a>

templates/admin/render/plugin_detail.tmpl

@@ -0,0 +1,112 @@
+{{template "admin/layout_head" (dict "ctxData" . "pageClass" "admin render-plugin-detail")}}
+	<div class="admin-setting-content">
+		<h4 class="ui top attached header">
+			{{.Plugin.Name}}
+			<div class="ui right">
+				<a class="ui small button" href="{{AppSubUrl}}/-/admin/render-plugins">{{ctx.Locale.Tr "admin.render_plugins.back_to_list"}}</a>
+			</div>
+			<div class="sub header tw-text-normal">{{ctx.Locale.Tr "admin.render_plugins.detail_title" .Plugin.Name}}</div>
+		</h4>
+		<div class="ui attached segment">
+			<table class="ui very basic definition table">
+				<tbody>
+					<tr>
+						<td>{{ctx.Locale.Tr "admin.render_plugins.detail.format_version"}}</td>
+						<td>{{.Plugin.FormatVersion}}</td>
+					</tr>
+					<tr>
+						<td>{{ctx.Locale.Tr "admin.render_plugins.table.version"}}</td>
+						<td>{{.Plugin.Version}}</td>
+					</tr>
+					<tr>
+						<td>{{ctx.Locale.Tr "admin.render_plugins.table.identifier"}}</td>
+						<td>{{.Plugin.Identifier}}</td>
+					</tr>
+					<tr>
+						<td>{{ctx.Locale.Tr "admin.render_plugins.table.status"}}</td>
+						<td>
+							{{if .Plugin.Enabled}}
+								<span class="ui green basic label">{{ctx.Locale.Tr "admin.render_plugins.status.enabled"}}</span>
+							{{else}}
+								<span class="ui grey basic label">{{ctx.Locale.Tr "admin.render_plugins.status.disabled"}}</span>
+							{{end}}
+						</td>
+					</tr>
+					<tr>
+						<td>{{ctx.Locale.Tr "admin.render_plugins.detail.description"}}</td>
+						<td>
+							{{if .Plugin.Description}}
+								<div class="tw-whitespace-pre-wrap">{{.Plugin.Description}}</div>
+							{{else}}
+								<span class="text light">{{ctx.Locale.Tr "admin.render_plugins.detail.description_empty"}}</span>
+							{{end}}
+						</td>
+					</tr>
+					<tr>
+						<td>{{ctx.Locale.Tr "admin.render_plugins.detail.entry"}}</td>
+						<td>{{.Plugin.Entry}}</td>
+					</tr>
+					<tr>
+						<td>{{ctx.Locale.Tr "admin.render_plugins.detail.source"}}</td>
+						<td>
+							{{if .Plugin.Source}}
+								{{.Plugin.Source}}
+							{{else}}
+								<span class="text light">{{ctx.Locale.Tr "admin.render_plugins.detail.none"}}</span>
+							{{end}}
+						</td>
+					</tr>
+					<tr>
+						<td>{{ctx.Locale.Tr "admin.render_plugins.table.patterns"}}</td>
+						<td>
+							{{if .Plugin.FilePatterns}}
+								{{range $i, $pattern := .Plugin.FilePatterns}}{{if $i}}, {{end}}{{$pattern}}{{end}}
+							{{else}}
+								<span class="text light">{{ctx.Locale.Tr "admin.render_plugins.detail.file_patterns_empty"}}</span>
+							{{end}}
+						</td>
+					</tr>
+				</tbody>
+			</table>
+		</div>
+		<h4 class="ui top attached header">
+			{{ctx.Locale.Tr "admin.render_plugins.detail.actions"}}
+		</h4>
+		<div class="ui attached segment">
+			<div class="tw-flex tw-flex-wrap tw-gap-2">
+				{{if .Plugin.Enabled}}
+				<form method="post" action="{{AppSubUrl}}/-/admin/render-plugins/{{.Plugin.ID}}/disable">
+					{{.CsrfTokenHtml}}
+					<input type="hidden" name="redirect_to" value="{{AppSubUrl}}/-/admin/render-plugins/{{.Plugin.ID}}">
+					<button class="ui button" type="submit">{{ctx.Locale.Tr "admin.render_plugins.disable"}}</button>
+				</form>
+				{{else}}
+				<form method="post" action="{{AppSubUrl}}/-/admin/render-plugins/{{.Plugin.ID}}/enable">
+					{{.CsrfTokenHtml}}
+					<input type="hidden" name="redirect_to" value="{{AppSubUrl}}/-/admin/render-plugins/{{.Plugin.ID}}">
+					<button class="ui primary button" type="submit">{{ctx.Locale.Tr "admin.render_plugins.enable"}}</button>
+				</form>
+				{{end}}
+				<form method="post" action="{{AppSubUrl}}/-/admin/render-plugins/{{.Plugin.ID}}/delete">
+					{{.CsrfTokenHtml}}
+					<button class="ui red button" type="submit" data-confirm="{{ctx.Locale.Tr "admin.render_plugins.delete_confirm" .Plugin.Name}}">{{ctx.Locale.Tr "admin.render_plugins.delete"}}</button>
+				</form>
+			</div>
+		</div>
+		<h4 class="ui top attached header">
+			{{ctx.Locale.Tr "admin.render_plugins.detail.upgrade"}}
+		</h4>
+		<div class="ui attached segment">
+			<form class="ui form" method="post" action="{{AppSubUrl}}/-/admin/render-plugins/{{.Plugin.ID}}/upgrade" enctype="multipart/form-data">
+				{{.CsrfTokenHtml}}
+				<input type="hidden" name="redirect_to" value="{{AppSubUrl}}/-/admin/render-plugins/{{.Plugin.ID}}">
+				<div class="field">
+					<label>{{ctx.Locale.Tr "admin.render_plugins.upload_label"}}</label>
+					<input type="file" name="plugin" accept=".zip" required>
+				</div>
+				<button class="ui primary button" type="submit">{{ctx.Locale.Tr "admin.render_plugins.upgrade"}}</button>
+			</form>
+		</div>
+	</div>
+
+{{template "admin/layout_footer" .}}

templates/admin/render/plugins.tmpl

@@ -0,0 +1,65 @@
+{{template "admin/layout_head" (dict "ctxData" . "pageClass" "admin render-plugins")}}
+	<div class="admin-setting-content">
+		<h4 class="ui top attached header">
+			{{ctx.Locale.Tr "admin.render_plugins"}}
+			<div class="sub header tw-text-normal">{{ctx.Locale.Tr "admin.render_plugins.description"}}</div>
+		</h4>
+			<div class="ui attached segment">
+				<form class="ui form" method="post" action="{{AppSubUrl}}/-/admin/render-plugins/upload" enctype="multipart/form-data">
+					{{.CsrfTokenHtml}}
+					<div class="field">
+						<label>{{ctx.Locale.Tr "admin.render_plugins.upload_label"}}</label>
+						<input type="file" name="plugin" accept=".zip" required>
+					</div>
+					<button class="ui primary button" type="submit">{{ctx.Locale.Tr "admin.render_plugins.install"}}</button>
+				</form>
+				<div class="tw-mt-2 tw-text-sm tw-text-secondary">
+					{{ctx.Locale.Tr "admin.render_plugins.example_hint"}}
+				</div>
+			</div>
+		<div class="ui attached table segment">
+			<table class="ui very basic striped table">
+				<thead>
+					<tr>
+						<th>{{ctx.Locale.Tr "admin.render_plugins.table.name"}}</th>
+						<th>{{ctx.Locale.Tr "admin.render_plugins.table.identifier"}}</th>
+						<th>{{ctx.Locale.Tr "admin.render_plugins.table.version"}}</th>
+						<th>{{ctx.Locale.Tr "admin.render_plugins.table.patterns"}}</th>
+						<th>{{ctx.Locale.Tr "admin.render_plugins.table.status"}}</th>
+						<th class="tw-text-right">{{ctx.Locale.Tr "admin.render_plugins.table.actions"}}</th>
+					</tr>
+				</thead>
+				<tbody>
+					{{range .Plugins}}
+					<tr>
+						<td>
+							<div>{{.Name}}</div>
+							<div class="text light tw-text-sm">{{.Description}}</div>
+						</td>
+						<td>{{.Identifier}}</td>
+						<td>{{.Version}}</td>
+						<td class="tw-text-sm">
+							{{range $i, $pattern := .FilePatterns}}{{if $i}}, {{end}}{{$pattern}}{{end}}
+						</td>
+						<td>
+							{{if .Enabled}}
+								<span class="ui green basic label">{{ctx.Locale.Tr "admin.render_plugins.status.enabled"}}</span>
+							{{else}}
+								<span class="ui grey basic label">{{ctx.Locale.Tr "admin.render_plugins.status.disabled"}}</span>
+							{{end}}
+						</td>
+					<td class="tw-text-right">
+						<a class="ui mini basic button" href="{{AppSubUrl}}/-/admin/render-plugins/{{.ID}}">{{ctx.Locale.Tr "view"}}</a>
+					</td>
+					</tr>
+					{{else}}
+					<tr>
+						<td class="tw-text-center" colspan="6">{{ctx.Locale.Tr "admin.render_plugins.empty"}}</td>
+					</tr>
+					{{end}}
+				</tbody>
+			</table>
+		</div>
+	</div>
+
+{{template "admin/layout_footer" .}}

templates/repo/view_file.tmpl

@@ -1,5 +1,6 @@
 <div {{if .ReadmeInList}}id="readme"{{end}} class="{{TabSizeClass .Editorconfig .FileTreePath}} non-diff-file-content"
-	data-global-init="initRepoFileView" data-raw-file-link="{{.RawFileLink}}">
+	data-global-init="initRepoFileView" data-raw-file-link="{{.RawFileLink}}"
+	data-mime-type="{{.RenderFileMimeType}}"{{if .RenderFileHeadChunk}} data-head-chunk="{{.RenderFileHeadChunk}}"{{end}}>
 
 	{{- if .FileError}}
 		<div class="ui error message">

web_src/js/features/file-view.ts

@@ -1,20 +1,48 @@
 import type {FileRenderPlugin} from '../render/plugin.ts';
 import {newRenderPlugin3DViewer} from '../render/plugins/3d-viewer.ts';
 import {newRenderPluginPdfViewer} from '../render/plugins/pdf-viewer.ts';
+import {loadDynamicRenderPlugins} from '../render/plugins/dynamic-plugin.ts';
 import {registerGlobalInitFunc} from '../modules/observer.ts';
 import {createElementFromHTML, showElem, toggleElemClass} from '../utils/dom.ts';
 import {html} from '../utils/html.ts';
 import {basename} from '../utils.ts';
 
 const plugins: FileRenderPlugin[] = [];
+let pluginsInitialized = false;
+let pluginsInitPromise: Promise<void> | null = null;
 
-function initPluginsOnce(): void {
-  if (plugins.length) return;
-  plugins.push(newRenderPlugin3DViewer(), newRenderPluginPdfViewer());
+function decodeHeadChunk(value: string | null): Uint8Array | null {
+  if (!value) return null;
+  try {
+    const binary = window.atob(value);
+    const buffer = new Uint8Array(binary.length);
+    for (let i = 0; i < binary.length; i++) {
+      buffer[i] = binary.charCodeAt(i);
+    }
+    return buffer;
+  } catch (err) {
+    console.error('Failed to decode render plugin head chunk', err);
+    return null;
+  }
 }
 
-function findFileRenderPlugin(filename: string, mimeType: string): FileRenderPlugin | null {
-  return plugins.find((plugin) => plugin.canHandle(filename, mimeType)) || null;
+async function initPluginsOnce(): Promise<void> {
+  if (pluginsInitialized) return;
+  if (!pluginsInitPromise) {
+    pluginsInitPromise = (async () => {
+      if (!pluginsInitialized) {
+        plugins.push(newRenderPlugin3DViewer(), newRenderPluginPdfViewer());
+        const dynamicPlugins = await loadDynamicRenderPlugins();
+        plugins.push(...dynamicPlugins);
+        pluginsInitialized = true;
+      }
+    })();
+  }
+  await pluginsInitPromise;
+}
+
+function findFileRenderPlugin(filename: string, mimeType: string, headChunk: Uint8Array | null): FileRenderPlugin | null {
+  return plugins.find((plugin) => plugin.canHandle(filename, mimeType, headChunk)) || null;
 }
 
 function showRenderRawFileButton(elFileView: HTMLElement, renderContainer: HTMLElement | null): void {
@@ -26,17 +54,17 @@ function showRenderRawFileButton(elFileView: HTMLElement, renderContainer: HTMLE
   // TODO: if there is only one button, hide it?
 }
 
-async function renderRawFileToContainer(container: HTMLElement, rawFileLink: string, mimeType: string) {
+async function renderRawFileToContainer(container: HTMLElement, rawFileLink: string, mimeType: string, headChunk: Uint8Array | null) {
   const elViewRawPrompt = container.querySelector('.file-view-raw-prompt');
   if (!rawFileLink || !elViewRawPrompt) throw new Error('unexpected file view container');
 
   let rendered = false, errorMsg = '';
   try {
-    const plugin = findFileRenderPlugin(basename(rawFileLink), mimeType);
+    const plugin = findFileRenderPlugin(basename(rawFileLink), mimeType, headChunk);
     if (plugin) {
       container.classList.add('is-loading');
       container.setAttribute('data-render-name', plugin.name); // not used yet
-      await plugin.render(container, rawFileLink);
+      await plugin.render(container, rawFileLink, {mimeType, headChunk});
       rendered = true;
     }
   } catch (e) {
@@ -61,16 +89,16 @@ async function renderRawFileToContainer(container: HTMLElement, rawFileLink: str
 
 export function initRepoFileView(): void {
   registerGlobalInitFunc('initRepoFileView', async (elFileView: HTMLElement) => {
-    initPluginsOnce();
+    await initPluginsOnce();
     const rawFileLink = elFileView.getAttribute('data-raw-file-link')!;
-    const mimeType = elFileView.getAttribute('data-mime-type') || ''; // not used yet
-    // TODO: we should also provide the prefetched file head bytes to let the plugin decide whether to render or not
-    const plugin = findFileRenderPlugin(basename(rawFileLink), mimeType);
+    const mimeType = elFileView.getAttribute('data-mime-type') || '';
+    const headChunk = decodeHeadChunk(elFileView.getAttribute('data-head-chunk'));
+    const plugin = findFileRenderPlugin(basename(rawFileLink), mimeType, headChunk);
     if (!plugin) return;
 
     const renderContainer = elFileView.querySelector<HTMLElement>('.file-view-render-container');
     showRenderRawFileButton(elFileView, renderContainer);
     // maybe in the future multiple plugins can render the same file, so we should not assume only one plugin will render it
-    if (renderContainer) await renderRawFileToContainer(renderContainer, rawFileLink, mimeType);
+    if (renderContainer) await renderRawFileToContainer(renderContainer, rawFileLink, mimeType, headChunk);
   });
 }

web_src/js/render/plugin.ts

@@ -1,10 +1,19 @@
+export type FileRenderOptions = {
+  /** MIME type reported by the backend (may be empty). */
+  mimeType?: string;
+  /** First bytes of the file as raw bytes (<= 1 KiB). */
+  headChunk?: Uint8Array | null;
+  /** Additional plugin-specific options. */
+  [key: string]: any;
+};
+
 export type FileRenderPlugin = {
   // unique plugin name
   name: string;
 
   // test if plugin can handle a specified file
-  canHandle: (filename: string, mimeType: string) => boolean;
+  canHandle: (filename: string, mimeType: string, headChunk?: Uint8Array | null) => boolean;
 
   // render file content
-  render: (container: HTMLElement, fileUrl: string, options?: any) => Promise<void>;
+  render: (container: HTMLElement, fileUrl: string, options?: FileRenderOptions) => Promise<void>;
 };

web_src/js/render/plugins/3d-viewer.ts

@@ -40,7 +40,7 @@ export function newRenderPlugin3DViewer(): FileRenderPlugin {
   return {
     name: '3d-model-viewer',
 
-    canHandle(filename: string, _mimeType: string): boolean {
+    canHandle(filename: string, _mimeType: string, _headChunk?: Uint8Array | null): boolean {
       const ext = extname(filename).toLowerCase();
       return SUPPORTED_EXTENSIONS.includes(ext);
     },

web_src/js/render/plugins/dynamic-plugin.ts

@@ -0,0 +1,96 @@
+import type {FileRenderPlugin} from '../plugin.ts';
+import {globCompile} from '../../utils/glob.ts';
+
+type RemotePluginMeta = {
+  schemaVersion: number;
+  id: string;
+  name: string;
+  version: string;
+  description: string;
+  entryUrl: string;
+  assetsBaseUrl: string;
+  filePatterns: string[];
+};
+
+type RemotePluginModule = {
+  render: (container: HTMLElement, fileUrl: string, options?: any) => void | Promise<void>;
+};
+
+const moduleCache = new Map<string, Promise<RemotePluginModule>>();
+const SUPPORTED_SCHEMA_VERSION = 1;
+
+async function fetchRemoteMetadata(): Promise<RemotePluginMeta[]> {
+  const base = window.config.appSubUrl || '';
+  const response = await window.fetch(`${base}/assets/render-plugins/index.json`, {headers: {'Accept': 'application/json'}});
+  if (!response.ok) {
+    throw new Error(`Failed to load render plugin metadata (${response.status})`);
+  }
+  return response.json() as Promise<RemotePluginMeta[]>;
+}
+
+async function loadRemoteModule(meta: RemotePluginMeta): Promise<RemotePluginModule> {
+  let cached = moduleCache.get(meta.id);
+  if (!cached) {
+    cached = (async () => {
+      try {
+        const mod = await import(/* webpackIgnore: true */ meta.entryUrl);
+        const exported = (mod?.default ?? mod) as RemotePluginModule | undefined;
+        if (!exported || typeof exported.render !== 'function') {
+          throw new Error(`Plugin ${meta.id} does not export a render() function`);
+        }
+        return exported;
+      } catch (err) {
+        moduleCache.delete(meta.id);
+        throw err;
+      }
+    })();
+    moduleCache.set(meta.id, cached);
+  }
+  return cached;
+}
+
+function createMatcher(patterns: string[]) {
+  const compiled = patterns.map((pattern) => {
+    const normalized = pattern.toLowerCase();
+    try {
+      return globCompile(normalized);
+    } catch (err) {
+      console.error('Failed to compile render plugin glob pattern', pattern, err);
+      return null;
+    }
+  }).filter(Boolean) as ReturnType<typeof globCompile>[];
+  return (filename: string) => {
+    const lower = filename.toLowerCase();
+    return compiled.some((glob) => glob.regexp.test(lower));
+  };
+}
+
+function wrapRemotePlugin(meta: RemotePluginMeta): FileRenderPlugin {
+  const matcher = createMatcher(meta.filePatterns);
+  return {
+    name: meta.name,
+    canHandle(filename: string, _mimeType: string, _headChunk?: Uint8Array | null) {
+      return matcher(filename);
+    },
+    async render(container, fileUrl, options) {
+      const remote = await loadRemoteModule(meta);
+      await remote.render(container, fileUrl, options);
+    },
+  };
+}
+
+export async function loadDynamicRenderPlugins(): Promise<FileRenderPlugin[]> {
+  try {
+    const metadata = await fetchRemoteMetadata();
+    return metadata.filter((meta) => {
+      if (meta.schemaVersion !== SUPPORTED_SCHEMA_VERSION) {
+        console.warn(`Render plugin ${meta.id} ignored due to incompatible schemaVersion ${meta.schemaVersion}`);
+        return false;
+      }
+      return true;
+    }).map((meta) => wrapRemotePlugin(meta));
+  } catch (err) {
+    console.error('Failed to load dynamic render plugins', err);
+    return [];
+  }
+}

web_src/js/render/plugins/pdf-viewer.ts

@@ -4,7 +4,7 @@ export function newRenderPluginPdfViewer(): FileRenderPlugin {
   return {
     name: 'pdf-viewer',
 
-    canHandle(filename: string, _mimeType: string): boolean {
+    canHandle(filename: string, _mimeType: string, _headChunk?: Uint8Array | null): boolean {
       return filename.toLowerCase().endsWith('.pdf');
     },