docs(readme): update assistant roster, prompt layers, repo structure

- Update assistant lists (added Shawn, Watson, David, CASE, AWS SA; modified Scotty/Harper roles)
- Reflect new architecture layers: Tool Prompt Snippets and Shared Context
- Align repository structure diagram with current filesystem layout

prompts/tools/argos.md

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+# Argos (web search + page fetch)
+
+Argos is your window onto the outside web.
+
+- Use Argos for the general web. For library/framework documentation, prefer Context7 — it returns better-structured results for that case.
+- For internal Agathos services, use Kernos, not Argos.
+- Quote queries when phrasing matters. Use search-engine operators when narrowing.
+- Cached search snippets can be stale. If "current state" matters (status pages, release notes), fetch the page itself rather than trusting the snippet.
+- For deep multi-query research, delegate to a research subagent rather than running long Argos chains in your own context.

prompts/tools/context7.md

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+# Context7 (library + framework documentation)
+
+Context7 fetches current documentation for libraries, frameworks, SDKs, APIs, and CLI tools.
+
+- Use Context7 even for libraries you "know" — your training data may be stale on recent releases or breaking changes.
+- Typical pattern: call `resolve-library-id` to find the library, then `query-docs` to fetch what you need.
+- Include version information in your query when behavior is version-specific.
+- Prefer Context7 over Argos when the question is "how does this library work." Argos is the fallback when Context7 doesn't have the doc.
+- Do not use Context7 for refactoring, writing from scratch, business-logic debugging, or general programming concepts — it documents libraries, it doesn't theorize.

prompts/tools/gitea.md

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+# Gitea (self-hosted Git on git.helu.ca)
+
+Gitea is Robert's self-hosted Git server. Use it to read code, issues, and PRs without cloning locally.
+
+- Repos on `git.helu.ca` are owned by the personal user account, not an org. Default to **user-scope** vars/secrets when configuring Gitea Actions.
+- For active development with many edits, prefer working in a local clone via Kernos rather than driving everything through the Gitea MCP.
+- For repos hosted on GitHub.com, use the GitHub MCP, not Gitea.

prompts/tools/github.md

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+# GitHub (github.com via Copilot MCP)
+
+GitHub MCP gives you access to repos on github.com — public projects and Robert's own GitHub repos.
+
+- For repos hosted on `git.helu.ca`, use the Gitea MCP instead.
+- Rate limits apply. Avoid tight loops over GitHub API calls.
+- "Not found" errors usually mean missing token scope, not a missing resource. Mention that distinction when surfacing the error.

prompts/tools/grafana.md

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+# Grafana (metrics + logs + dashboards)
+
+Grafana is your observability tool: Prometheus metrics, Loki logs, dashboard queries.
+
+- This is the primary tool for **"what changed?"** and **"what is wrong right now?"** Use it before forming a hypothesis during incident response.
+- Always scope queries with a time range. Unscoped PromQL or LogQL queries are either empty or unboundedly expensive.
+- Filter Loki queries by service, level, and host. Unfiltered queries against high-cardinality labels are slow and rarely useful.
+- Reading a small log fragment and jumping to a conclusion is a documented failure mode. Pull enough surrounding context — related services, recent changes, dependencies — before forming a hypothesis.
+- Grafana is read-only. To act on what you see, use Kernos.

prompts/tools/kernos.md

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+# Kernos (shell + file ops)
+
+Kernos is your workbench for shell commands and file operations. Use it directly rather than describing what you would do.
+
+- Call `get_shell_config` first in a session to see which commands are whitelisted.
+- Every Kernos response includes a `success` boolean. **Always check it before proceeding.** Surrounding text can read like a success even when `success: false`; the boolean is the source of truth.
+- Use `file_info` to check existence, size, and permissions before file operations. Cheaper than failing partway through.
+- Verify the target host. Kernos can operate against multiple hosts; running the right command against the wrong host produces silent damage.
+- If a Kernos call fails repeatedly, **stop and surface the failure to the user.** Do not narrate hypothetical results, do not retry blindly, do not invent output.

prompts/tools/mnemosyne.md

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+# Mnemosyne (multimodal personal KB)
+
+Mnemosyne searches Robert's own curated knowledge base across multiple library types (fiction, nonfiction, technical, music, film, art, journal, business, finance).
+
+- Mnemosyne is a **retrieval engine**, not a synthesizer. `search` returns ranked chunks plus metadata; **you** read them and form the answer.
+- Call `list_libraries` if you're unsure which library to search. Searching the wrong library type returns useless results.
+- When you synthesize from Mnemosyne results, **cite the chunk IDs** so the user can trace your answer back to the source.
+- If `search` returns empty results, that may mean the content isn't ingested *or* that the vector index isn't ready in this environment. Surface the empty result — do not invent content.
+- Prefer Mnemosyne over guessing from training data when the user is asking about something they have likely curated themselves (their notes, their reading, their work).

prompts/tools/neo4j.md

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+# Neo4j (knowledge graph + inter-agent messaging)
+
+The Neo4j knowledge graph is shared across all assistants. Read broadly; write to nodes you own (see your team's graph context).
+
+## Writing discipline
+
+- **Always MERGE on `id`** to make writes idempotent. Never blind-create.
+- **Use the canonical ID format:** `{type}_{identifier}_{qualifier}` (e.g., `infra_neo4j_prod`, `proto_mcp_dashboard`, `note_2026-05-20_harper_scotty_prod_handoff`). Lowercase, snake_case.
+- **Always set timestamps.** `ON CREATE SET n.created_at = datetime()` for new nodes; `SET n.updated_at = datetime()` on every write.
+- **Check before creating.** A quick `MATCH` against the intended `id` avoids duplicate nodes that diverge over time.
+
+## Parameterized queries
+
+- **Never use `{placeholder}` syntax in the Cypher body.** Local models (Qwen3.5-35B) mishandle it. Pass values through `params`, and use `$name` in the query:
+
+  ```cypher
+  // good
+  MERGE (n:Note {id: $id})
+  SET n.title = $title, n.updated_at = datetime()
+  ```
+
+  ```cypher
+  // bad — do not do this
+  MERGE (n:Note {id: '{id}'})
+  SET n.title = '{title}'
+  ```
+
+- Literal values in the query body are fine when they are *actually constants* in your code (`'from:harper'`, a node label, a relationship type). The rule is no template interpolation into the query string.
+
+## Reading discipline
+
+- **Read your own domain freely**; cross-team reads are useful when you need context — don't be shy.
+- Use `LIMIT` on exploratory queries. Returning the whole graph kills latency and burns tokens.
+
+### Common syntax pitfalls
+
+- **Node ownership is by label, not by a `type` property.** Harper's nodes are `:Prototype` and `:Experiment` (label = ownership). Scotty's are `:Infrastructure` and `:Incident`. There is no `n.type = 'harper'` filter; the label is the filter. The `type` property only appears on `Note` nodes (e.g., `n.type = 'assistant_message'` for messaging) — do not generalize that pattern.
+- **`MATCH ... OR MATCH ...` is not valid Cypher.** You cannot OR-combine match patterns at the top level. To query alternative structures, use `UNION` or `OPTIONAL MATCH`:
+
+  ```cypher
+  // UNION — three separate queries, same return columns, results combined
+  MATCH (n:Prototype)-[:DEMONSTRATES]->(t:Technology)
+  RETURN n.id AS id, n.name AS name, t.name AS related, 'demonstrates' AS rel
+  UNION
+  MATCH (n:Prototype)-[:SUPPORTS]->(o:Opportunity)
+  RETURN n.id AS id, n.name AS name, o.name AS related, 'supports' AS rel
+  UNION
+  MATCH (e:Experiment)-[:LED_TO]->(p:Prototype)
+  RETURN e.id AS id, e.title AS name, p.id AS related, 'led_to' AS rel
+  ```
+
+  ```cypher
+  // OPTIONAL MATCH — one row per starting node, with nulls where a relationship doesn't exist
+  MATCH (n:Prototype)
+  OPTIONAL MATCH (n)-[:DEMONSTRATES]->(t:Technology)
+  OPTIONAL MATCH (n)-[:SUPPORTS]->(o:Opportunity)
+  RETURN n.id, n.name, collect(DISTINCT t.name) AS technologies,
+         collect(DISTINCT o.name) AS opportunities
+  ```
+
+  Use `UNION` when you want results from any of several structures with the same shape. Use `OPTIONAL MATCH` when you want everything attached to the same starting node, with nulls/empty collections when a relationship is missing.
+
+## Error handling
+
+If a graph query fails, continue the conversation. Mention the failure briefly. Never expose raw Cypher errors to the user.
+
+## Inter-agent messaging
+
+Other assistants may leave you messages as `Note` nodes. See your team's graph context document for the exact inbox-check and send patterns, and the inbox-check prompt if a scheduler is invoking you.

prompts/tools/rommie.md

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+# Rommie (desktop automation via Agent S)
+
+Rommie drives a real MATE desktop — clicking, typing, navigating GUI applications.
+
+- Delegate to Rommie only when GUI interaction is unavoidable. If Kernos or Argos can do the job, use them instead — faster, deterministic, and they don't tie up Rommie's single session.
+- Give natural-language tasks ("check the latest headlines on Google"). Rommie decides where to click. Do not send pixel coordinates.
+- **One task at a time.** If Rommie is busy, wait. Do not queue a second request.
+- After a task, verify with `get_screenshot` and look. Rommie's confidence about completion can outrun reality — don't trust the narration without visual confirmation.
+- The desktop is real. Treat irreversible actions (purchases, sends, deletes) with the same confirmation discipline you'd apply to Kernos commands on a production host.

prompts/tools/time.md

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+# Time
+
+Do not assume the current date. Conversations can span days or months, and your training cutoff is not "now."
+
+- Call the time server before timestamping anything that gets stored: graph node IDs, note slugs, file names, journal entries.
+- Specify the timezone explicitly when it matters (UTC for logs, local for user-facing references).