Merge pull request #26 from rhyannonjoy/issue-25-add-Cascade-web-fetch-notes

[add] Windsurf-Cascade KPL (Issue #25)

Author: dacharyc

SPEC.md

@@ -1504,15 +1504,15 @@ becomes available.
 ### Known Platform Limits
 
 | Platform | Truncation Limit | Source | Confidence | Notes |
-|----------|-----------------|--------|------------|-------|
+| ---------- | ----------------- | -------- | ------------ | ------- |
 | Claude Code | ~100,000 chars | [Reverse engineering](https://giuseppegurgone.com/claude-webfetch) | High | Trusted sites serving `text/markdown` under 100K chars bypass summarization model entirely. Content over this threshold goes through a summarization model that may lose information. |
 | MCP Fetch (reference server) | 5,000 chars (default) | [Official docs](https://pypi.org/project/mcp-server-fetch/) | High | Default `max_length` is 5,000 chars. Configurable up to 1,000,000. Supports chunked reading via `start_index`. |
 | Claude API (web_fetch tool) | ~20,700 chars - default, unset | [empirical testing](https://rhyannonjoy.github.io/agent-ecosystem-testing/) | Medium | Optional `max_content_tokens` parameter can cap content length, but no default truncation limit is documented. Distinct implementation from Claude Code client-side tool. Default truncation ~20,700 chars when unset - ended mid-word. `max_content_tokens` is approximate — setting 5,000 returned 17,186 chars. Truncation occurs mid-token. CSS stripped effectively unlike Claude Code. HTML boilerplate 81–97.5% before first heading; Markdown reduces content 77%. JS-rendered pages return static shell only. |
 | Google Gemini (URL context) | Unknown | [empirical testing](https://rhyannonjoy.github.io/agent-ecosystem-testing/) | Medium | Docs state a 34 MB max fetch size per URL, but this is a retrieval ceiling, not a processing limit. How much content actually reaches the model after fetching is undocumented. 20 URL hard limit per request, `400 INVALID_ARGUMENT` if exceeded, zero tokens consumed. Truncation boundary unknown — retrieved content is injected into context without a testable field; `tool_use_prompt_token_count` is the only available size proxy, <1% variance across runs. PDF failed consistently despite being a documented supported type; YouTube succeeded despite being documented as unsupported. `url_context_metadata` order is non-deterministic. Tested on `gemini-2.5-flash` only — behavior may vary across supported models. |
 | OpenAI (web search) | Unknown | [empirical testing](https://rhyannonjoy.github.io/agent-ecosystem-testing/) | Medium | 128K token context window for web search. `search_context_size` parameter (low/medium/high) controls context amount but no per-page truncation limit is surfaced; when the tool invokes, any truncation of retrieved source content occurs before the model generates a response and isn't observable via the APIs. Consistent latency lever in Chat Completions API track, high ~1.5–1.7× slower, inconsistent in Responses API track. Source count stable at 12 regardless of context size. Tool invocation conditional and deterministic: static facts and trivial math don't invoke the tool. Domain filtering documented but non-functional via Python SDK — allow-list worked once on `web_search_preview`, never on `web_search`; block-list never succeeded across 6 runs, 2 tool types, 2 models. `search_queries_issued` appends training-era year strings despite running in 2026. Tested on `gpt-4o` + `gpt-4o-mini-search-preview` - behavior may vary across supported models. |
 | Cursor | Method-dependent | [empirical testing](https://rhyannonjoy.github.io/agent-ecosystem-testing/) | High | No documented truncation limit, behavior varies between backend methods `WebFetch MCP` ~28KB, `urllib` ~72KB, other routes 240KB+; `Auto` agent routing opaque; Cursor autonomously selects fetch mechanism. On timeout, falls back to `curl` (unfiltered HTML, 16MB+ observed). Requests `text/markdown` via `Accept` header. No token limit detected (tested 6.68M tokens). Perfect reproducibility for same URL; high variance for small files across sessions. |
 | GitHub Copilot | No fixed ceiling detected | [empirical testing](https://rhyannonjoy.github.io/agent-ecosystem-testing/) | Medium | No documented web fetch or truncation details; tool selection is non-deterministic and not controllable by prompt. `fetch_webpage` identified through logs only; performs relevance-ranked semantic excerpts with `...` elision markers in HTML-to-Markdown transformation with chunk-based reassembly; output order doesn't always reflect page reading order. No size limit detected across 55 runs; `curl` substitution delivers full retrieval, raw bytes in server format with no transformation layer. `Auto` model routing dispatches across multiple models with no documented routing logic. Tested on `Claude Haiku 4.5`, `Claude Sonnet 4.6`, `GPT-5.3-Codex`, `GPT-5.4`, `Grok Code Fast 1`, `Raptor mini (Preview)`. |
-| Windsurf | Unknown | -- | -- | Docs state it "chunks up web pages" and "skims to the section we want." No specific limits documented. |
+| Windsurf Cascade | No fixed ceiling detected at retrieval stage, but agent-dependent write ceiling | [empirical testing](https://rhyannonjoy.github.io/agent-ecosystem-testing/) | High | Two-stage pipeline `read_url_content` returns chunk index with summaries, metadata, requires sequential `view_content_chunk` calls. Full retrieval agent, doc size dependent. Full retrieval doesn't guarantee full content delivery. Agents often retrieve fully ~<14 chunks, spotty ~35, sparse sampling 50+. Includes per-chunk trucation, some chunk summaries include byte-count loss notices. CSS-heavy, SPAs often retrieve ~20-35% expected rendered size. `@web` syntax redundant with URL. Read-write asymmetry: agents that self-report full retrieval frequently fail to reproduce semantically-meaningful content with `curl` HTML/JS shells, false completions, cross-agent file reuse. |
 
 **Thank you to contributors!**
 
@@ -1521,6 +1521,7 @@ becomes available.
 - GitHub Copilot limitations contributed by [Rhyannon Rodriguez](https://rhyannonjoy.github.io/agent-ecosystem-testing/)
 - Google Gemini (URL context) limitations contributed by [Rhyannon Rodriguez](https://rhyannonjoy.github.io/agent-ecosystem-testing/)
 - OpenAI (web search) limitations contributed by [Rhyannon Rodriguez](https://rhyannonjoy.github.io/agent-ecosystem-testing/)
+- Windsurf Cascade limitations contributed by [Rhyannon Rodriguez](https://rhyannonjoy.github.io/agent-ecosystem-testing/)
 
 ### What This Means for Threshold Selection