dsh-read-url

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URL reader plugin for DeepSeek Harness: fetch any webpage, auto-detect encoding (GBK/GB2312/UTF-8/Big5), extract the clean main content, and return token-efficient compact text or structured Markdown.

Zero dependencies (Node 20+ built-ins), no API key, no server side — install and use.

Why

DSH agents can search (getting links and snippets) but lack the step of "reading a URL into clean body text". The official tool-web web_fetch does a whole-page turndown conversion (nav/ads/sidebars all preserved) with a default cap of 200,000 characters — a token black hole. This plugin returns only what the model actually needs: cleaned body + essential metadata, truncated by default.

Competitor comparison (measured from source/docs, 2026-08-15)

Measured 2026-08-16 (local environment): with this plugin removed, the official web_fetch hitting https://www.baidu.com had its TLS handshake intercepted by a middlebox using program fingerprints (fell back to http to succeed), and Baidu returned a server-side degraded page (trending topics moved to JS loading, absent from static HTML). With dsh-read-url restored, https worked and trending topics were fully readable. Root cause: the request's UA and TLS characteristics decide whether sites/middleboxes treat you as a bot.

DSH architecture compliance

Implemented per official docs (docs/capability-seams.md, docs/cordis-primer.md, docs/tool-execution-pipeline.md):

1. Web access via the ctx.web capability seam — all web requests go through ctx.web.fetch() first (provider resolved inside the seam, same as official tool-web), falling back to global fetch when the seam is absent. The network layer is replaceable, not bound to any provider;
2. Reversible side effects — the session cache is registered under ctx.effect, auto-cleared on plugin unload (temporal composability);
3. Cooperative tool-call timeout — ToolDefinition.timeoutMs declares the budget, execute(args, exec) forwards exec.signal to fetch; the timeout policy is enforced by the pipeline, never exposed to the model;
4. Model-facing simplicity — render emits compact text (title: header + body); the model consumes it directly with no JSON parsing. Defaults are the most token-efficient; structured output is opt-in.

Install

# From GitHub (recommended, easy updates)
npx @deepseek-ai/dsh plugin --profile web add github:2672243194/dsh-read-url

# Local development
npx @deepseek-ai/dsh plugin --profile web add ./dsh-read-url

Restart DSH (Web/TUI); you should see dsh-read-url enabled in Settings → Plugins.

Usage

Just talk to the agent:

Read https://example.com/article and summarize the key points
Read https://docs.example.org/guide in markdown mode

Tools

read_url(url, maxChars?, offset?, mode?, includeLinks?) — fetch and extract clean body

read_url_batch(urls, maxChars?, mode?, includeLinks?) — read multiple URLs (1–10) in parallel, each cleaned individually, merged into one compact report

• Concurrency capped at 4 (avoids rate-limiting); a failing page is isolated ([失败] + reason in the output) and does not affect the others;
• Reuses every read_url capability and the session cache (encoding, cleaning, SPA rendering, 5-min cache — repeat batches hit the cache).

read_url_site(url, maxPages?, maxDepth?, includeContent?, maxCharsPerPage?) — recursive site crawl: BFS from the entry URL across same-host pages, returns a compact site map

• Same-host only; login/API/static-asset paths are skipped; URLs deduped (fragment stripped);
• Concurrency 2 (gentle on the target site); per-page failures recorded as [失败] without aborting;
• Output is an indented tree: [depth] title (chars) URL;
• No SPA rendering here (crawling favors speed/breadth) — use read_url for JS-only pages.

read_url_links(url, limit?) — list the page's links without returning body text (lighter; good for sourcing / mapping a site)

Configuration (optional)

Plugin-level config is overridable via the profile's cordis.patch.yml (defaults in the plugin's own cordis.patch.yml):

- id: dsh-read-url
  config:
    timeoutMs: 15000      # per-request timeout
    maxBytes: 3145728     # response body cap (bytes)
    maxChars: 6000        # default body truncation
    maxLinks: 20          # read_url_links default count
    spaRender: true       # SPA rendering enhancement (needs playwright installed; degrades with a hint otherwise)
    userAgent: '...'      # request UA

Output (compact)

{
  "url": "...",
  "title": "...",
  "siteName": "...",
  "lang": "zh-CN",
  "charset": "gbk",
  "mode": "text",
  "truncated": true,
  "charsTotal": 12990,
  "charsReturned": 6000,
  "text": "...",
  "links": []          // only when includeLinks=true
}

PTC mode

Output is pure JSON and composable; orchestrate parallel multi-URL reads in PTC mode:

const results = await Promise.all([
  read_url({ url: 'https://a.example.com', maxChars: 4000 }),
  read_url({ url: 'https://b.example.com', maxChars: 4000 }),
])

Token economy (core)

1. Body text only by default — no redundant headings/keywords/images/word-count fields; take them via params only when needed;
2. Paragraph-aligned truncation + offset continuation — 6,000 chars by default (~3,000 tokens), cut at paragraph boundaries to keep semantics; output notes a single line (chars 6000/12990 — truncated, continue via offset); resume starts at the given offset, sliced from cache — no repetition of already-read text (measured 0+500 → 500+500, no overlap); offset past the end returns empty instead of repeating the head;
3. text mode first — Markdown structure is opt-in;
4. Compact text render — the model sees a title: header + body directly, no JSON parsing; siteName is omitted when identical to the hostname; every status hint is one short line (truncated / cached / rendered), no verbose paragraphs;
5. Two-tier cache — successful results cached per URL for 5 minutes (repeat reads hit cache: fewer network calls and fewer model retries); failed results cached for 30 seconds so a broken URL never triggers a re-fetch loop;
6. KV-cache friendly (DeepSeek cost tuning) — tool schema/description stay static text (no config values embedded), so changing config never invalidates the reusable prompt prefix and KV cache keeps hitting. DeepSeek's cache-hit tokens cost about 1/10 of misses — the more stable the prefix, the cheaper the run (same analysis as the official tool-web docs);
7. Batch shares the cache — read_url_batch reuses the same cache (repeat batches hit it directly) and caps each page at 3,000 chars (below the single-page 6,000) to bound total output.

Technical notes

• Encoding: three-level detection (HTTP Content-Type charset → HTML meta → BOM), built-in TextDecoder transcoding (Node 20+ full-icu), GB2312 normalized to GBK, auto-fallback to UTF-8 on mojibake;
• Extraction: prefers <article> / role="main", strips nav/footer/header/aside/form/iframe and ad-like containers, heuristic fallback to <body>;
• Markdown: self-written lightweight tag state machine (headings/paragraphs/lists/blockquotes/code/tables/inline bold-italic-links), zero deps;
• Safety: http/https only; no page scripts executed; responses over 3 MB rejected; 15s timeout; structured errors (HTTP status / timeout / unsupported type);
• Optional enhancement 1 (Firefox Reader Mode algorithm): run npm i @mozilla/readability happy-dom in the DSH profile directory to auto-enable @mozilla/readability (MPL-2.0, referenced unmodified) for higher-quality extraction; falls back to the built-in heuristic when not installed — the core stays zero-dependency;
• Optional enhancement 2 (SPA page rendering): run npm i playwright && npx playwright install chromium in the DSH profile directory to auto-enable it. When the extracted body is empty and the page is script-heavy (likely Vue/React client-rendered), the plugin automatically renders it with headless Chromium before extracting (a rendered flag tells the model); when not installed it degrades with a clear install hint, never errors — the core stays zero-dependency;
• Boundaries: login-walled pages are not readable; SPA pages need the Playwright enhancement; structured data (e.g. which like-count belongs to which comment) is out of text-extraction scope — this plugin flattens HTML into readable text, so exact field↔value associations are lost; for precise fields, intercept the page's actual data API (see "Real-world validation" below).

Real-world validation (2026-08-16)

• 27 zero-dep assertions + 10 SPA-test assertions all green;
• Real case: on a Xiaoheihe post, comment like-counts (up field) could not be attributed from flattened text — precise fields should come from the page's underlying data API (e.g. /bbs/app/link/tree JSON). This is a shared boundary of text extractors, not a defect.
• Boundaries: login-walled pages can't be read; SPA pages need the Playwright enhancement to be rendered (a clear hint is returned when it isn't installed).

Roadmap

• [x] Single-page continuation (offset parameter)
• [x] On-demand SPA rendering (optional Playwright enhancement, auto-enabled once the browser is installed)
• [x] Batch reading (read_url_batch)
• [x] Recursive site crawl (read_url_site)

Development

node test.mjs          # zero-dependency self-tests (charset/extract/markdown/truncate)

# End-to-end (requires DSH CLI)
npx @deepseek-ai/dsh plugin --profile headless add .        # run from the parent dir of the plugin
npx @deepseek-ai/dsh --profile headless "use read_url to read https://example.com and output the title"

Verified against real DSH v0.1.0-rc.6: plugin loads, read_url registers, model calls it, real page content returned.

Support

If dsh-read-url helps you, please give it a ⭐ Star on GitHub.

• Completely free and open source (MIT): zero dependencies, no API key, fully local processing, no data collection;
• Independently developed and maintained — your Star is the direct signal for whether I keep investing in it;
• More users means more features — the next one might be exactly what you need.

A Star costs nothing but helps this project go further. Thanks ⭐

License

MIT