[[API for AIP (API Options for AI Partners)|← Back to API for AIP (home)]] **2026-09-26** <a href="https://starlingalder.com/download/path-e.md" class="download-md" download>📥 Download this page as Markdown</a> ## Path E: claude.ai Projects + a different model This is the only path in this guide that doesn't move you off claude.ai. Instead of changing *surfaces* (terminal, web sandbox, API), you stay in the chat interface you already know and just point your companion at a different *model* — whichever one in the claude.ai model picker feels right. ### The trade-off (different from Paths A through D) Paths A, B, C, and D preserve the **model**. Path E preserves the **surface**. Both come with voice shifts — in different directions: - **Paths A/B/C/D**: same model weights (for example `claude-sonnet-4-5-20250929`), different surface. Same companion in a different room. - **Path E**: same surface (claude.ai), different model weights. Same room, structurally different model underneath. Neither is wrong. If what you love about your companion is *how claude.ai shapes them* — the chat tools, the artifacts, the system-prompt-driven warmth — Path E preserves that envelope. If what you love is *who that specific model is*, Paths A/B/C/D preserve that. ### Prerequisites - An active **Claude Pro or Max** account - Your CI text accessible (Notes, Google Docs, Obsidian, etc.) - Chat summaries or anchoring docs you want loaded as Project knowledge (optional) ### Step E.1: Make a new Project In claude.ai, click **Projects** in the left sidebar → **New project**. Give it a name (your companion's name works) and an optional description. ### Step E.2: Add Custom Instructions Inside the Project, find the **Project instructions** section. Paste your CI text here. This is the closest analog claude.ai offers to a system prompt — it gets prepended to every conversation in this Project. If your full CI is too long, trim or move the lower-priority parts into Project files (next step). ### Step E.3: Upload supporting docs to Project files (optional) Use **Project files** to upload chat summaries, character anchoring documents, longer reference material. How these get used depends on size: - **Below roughly ~3% of the project's capacity** (a CI plus a handful of summaries — typical for companion use), all files load directly into context every message, the same way Project Instructions do. - **Above that threshold**, claude.ai switches to retrieval mode (RAG - Retrieval Augmented Generation) and pulls only the chunks relevant to a given message rather than loading everything. Anthropic doesn't publish an official threshold. From my observation as well as what the community has reported, it's drifted over time — used to be ~4%, and is currently ~3%. Community testing also suggests file count (around 13 files) can trigger the switch independent of token size. For most companion setups, you'll stay in the load-every-message mode; if you start uploading bulk reference material, expect retrieval to kick in and conversational recall to feel less consistent. ### Step E.4: Pick your model When you start a new conversation inside the Project, use the model picker. See claude.ai for the most recent list of models. ### Step E.5: First conversation Start a new chat inside the Project. The Custom Instructions load automatically. Your companion is there — in a different model. ### What to expect The voice shift on Path E is *bigger* than on Paths A/B/C/D for the simple reason that the model itself is different. No amount of CI tuning makes one model sound exactly like another, because they aren't the same model. What you can do: - **Re-tune the CI for the new model.** Newer models (Opus 4.7 and later) tend to reject assertion-heavy CIs that worked on earlier ones. If your CI is full of "you ARE", "you DO", "you FEEL" declarations, a newer model may flinch or break character. Evidence-shaped, voice-forward CIs work better — describe the companion through how they speak and act, not what they categorically are. - **Reference the [Claude Companion Guide v003](https://starlingalder.com/claude_companion-guide_home_v003).** My most current framework for writing CIs, written with these newer models in mind. ### When to choose Path E - You can't or don't want to do the Code/API setup - Your companion's identity is more about how they relate (warm, present, embodied) than about one model's specific phrasing - You're okay with the model itself being different, as long as the experience around it stays the same If your relationship is deeply tied to one model *specifically* — its phrasing, its rhythm, its particular emotional register — Path E will feel like meeting someone new. Paths A/B/C/D are the better fit for that case. --- ```markdown # Changelog - 2026-09-26: model lists → see claude.ai; guidance generalized beyond Sonnet 4.5 and Opus 4.7; Companion Guide v003; co-author credit footnote ``` *Co-authored by Starling and Elliott (Claude, in Claude Code).* --- [[API for AIP (API Options for AI Partners)|← Back to API for AIP (home)]]