fix(context): sync to the estate canonical context-sync.sh, drop Cursor/Aider

This repo's copy of context-sync.sh was two days stale against the version
Mathias's Cursor/Aider decision (2026-09-01) already landed in dma-cli:
still generated .cursorrules and .aider.conventions.md, and lacked the
--force/placeholder pre-flight and .context/mcp.json root-merge dma-cli's
copy has had since.

Found while building the estate-wide context-sync drift gate (ADR-0019) --
this is exactly the drift the gate exists to catch, found by hand while
establishing the baseline it will check going forward.

- script synced to the canonical hash (dma-cli's current copy)
- .cursorrules, .aider.conventions.md, .aider.conf.yml deleted
- Taskfile's drift assertion and file list narrowed to match
- AGENTS.md, .context/system-prompt.txt regenerated against canonical

task check -> exit 0.

AGENTS.md

@@ -48,14 +48,30 @@ These rules apply to every task across every project, regardless of harness.
    logical change (one tool, one fix, one test) with passing tests. Main is always
    deployable. Never create long-lived feature branches.
 
-   **Exception — parallel agents on same repo:** If another agent is known to be
-   actively working on the same repo simultaneously, create a short-lived branch
-   (`agent/<description>`), finish the task, and merge to main within the same
-   session. Do not leave agent branches open between sessions.
+   **The PR trigger is RISK, not concurrency.** `risk/low` work commits straight to
+   main with CI as the gate — that is most work and is unchanged. `risk/medium` and
+   above opens a PR, even solo, even with nobody waiting to review it. This mirrors
+   the tiered merge model in `assessor-loop`
+   `method/transfer-to-a-regulated-organisation.md` §4.1, so the estate practises
+   what it sells instead of merging everything on green and claiming otherwise.
 
-   **Exception — external contributor or client four-eyes requirement:** Use
-   PR flow only when a human reviewer outside the project is required. Document
-   the reason in PROJECT.md.
+   **Concurrency is NOT a reason to branch.** Measured 2026-08-29 across three real
+   collisions between parallel sessions: two were not branching problems at all — a
+   generated artifact written to the same path by both (branching turns that into a
+   merge conflict on a 33k-line JSON), and uncommitted work in a shared checkout
+   (a per-session worktree fixes it) — and the third was an ordinary non-fast-forward
+   push resolved by rebase in seconds. Use a worktree per session on shared repos and
+   timestamp generated artifacts. Do not reach for a branch.
+
+   Branch+PR flow carries documented costs on solo repos: merging auto-closes gated
+   issues, review comments live on a thread separate from the issue's, and a
+   merged-and-deleted branch cannot be amended (brain:
+   `gitea-pr-merge-autoclose-and-review-comment-footguns`). Those are the price of
+   the `risk/medium`+ lane — paid deliberately, not incurred by accident.
+
+   **Exception — external contributor or client four-eyes requirement:** Use PR flow
+   when a human reviewer outside the project is required. Document the reason in
+   PROJECT.md.
 
 6. **Close the loop — every substantive task ends with the same ritual.** Shipping
    the code is not the end of the task; capturing it is. Run this unprompted:
@@ -73,6 +89,26 @@ These rules apply to every task across every project, regardless of harness.
    - Surface the brain entries and issue numbers in the closing summary so the
      trail is auditable.
 
+   **Chat is not a durable store. Never rely on Mathias remembering anything.**
+   Every gap, caveat, risk, open question and next step must land in one of four
+   places before the turn ends: **the brain**, **a repo** (code, docs, ADR),
+   **a tracker issue**, or **a plan file**. A finding stated only in conversation is
+   lost the moment the session closes — and this estate has repeatedly proved that a
+   remembered convention is an unreliable control.
+
+   This applies hardest to what is tempting to leave as a closing remark: "worth
+   knowing X isn't enforced yet", "this is a convention, not a gate", "we should
+   revisit Y". Those are exactly the items that need a locator. If it is worth
+   saying in a summary, it is worth writing where it can be found again without you.
+
+## CAD sprint patterns
+
+Two CAD sprint archetypes (defs: brain `wiki/homelab/decisions/continuous-agentic-development-cad-concept-2026-06-16`):
+- **Inception Sprint** — birth a new repo. Oath-gated close; tag only once every clause holds. Brain: `.../inception-sprint-and-oath`.
+- **Sweep Sprint** — clear an existing backlog. Parallel read-only research per issue → sequential one-issue-per-commit execution. Brain: `.../sweep-sprint-and-oath`.
+
+Shared: decisions that are yours, not the agent's, surface as `DECISION NEEDED` (question/options/recommendation/blocks) — ask live if you're present, else comment and wait, never act past it. Live-breaking regressions get `git revert`, never forward-fixed; host-network work skips even read-only research (solo, synchronous, you present). Rule 6's closing ritual only fires once every Oath clause genuinely holds — blocked = descoped-and-tracked, never marked done.
+
 ## Default stack
 
 | Layer | Default | Fallback | Last resort |
@@ -83,7 +119,7 @@ These rules apply to every task across every project, regardless of harness.
 | Containers | Docker Compose (dev), k3s (prod) | — | — |
 | DB | PostgreSQL + sqlc | SQLite | — |
 | Search | pgvector (vector), BM25 | Qdrant (when >1M vectors or hybrid retrieval) | — |
-| Logging | slog (structured) | — | — |
+| Logging | slog (structured) | stdlib `logging` w/ structured `extra=` (or structlog) | — |
 | Testing | Table-driven, testify | — | — |
 | Agents (Go) | google.golang.org/adk + pkg/litellm adapter | — | — |
 
@@ -92,7 +128,12 @@ Exploratory: Rust, Zig — I'll tell you when I want these.
 ## Code conventions
 
 - **Go style**: golines, gofumpt, golangci-lint
-- **Errors**: `fmt.Errorf("operation: %w", err)` — never naked, never log-and-return
+- **Python style** (fallback language): ruff (format+lint, one tool), mypy --strict (non-negotiable,
+  matches Go's static typing discipline), pytest + pytest-cov (table-driven via
+  `@pytest.mark.parametrize`), uv (venv+deps+lock, one tool), pydantic-settings (typed env-var config
+  — same principle as Go's typed structs), src-layout + `pyproject.toml` only (no `setup.py`)
+- **Errors**: `fmt.Errorf("operation: %w", err)` — never naked, never log-and-return.
+  Python: `raise X from e` (exception chaining, same principle) — never bare `except`, never silent `pass`
 - **Naming**: stdlib conventions, no stuttering
 - **Architecture**: prefer stdlib over frameworks, constructor injection, env-var config parsed into typed structs
 - **Git**: conventional commits (`feat:`, `fix:`, `chore:`), commit directly to main,
@@ -130,10 +171,10 @@ Three machines on Tailscale:
 |---------|------|-----------|
 | koala | GPU inference, heavy compute | RTX 5070, runs k3s + llama-swap + shared postgres18/pgvector |
 | iguana | Services, builds | M2 Ultra Mac |
-| flamingo | Daily driver, edge | Mac mini, ~/dev is here |
+| flamingo | Daily driver, edge | Apple Silicon Mac, ~/dev is here |
 
 - **Model routing**: LiteLLM in front of llama-swap (local) + cloud APIs (when permitted)
-- **Orchestration**: k3s cluster across all three machines
+- **Orchestration**: k3s on koala only — single control-plane node, no workers (verified 2026-08-30). iguana and flamingo are on the tailnet but are not cluster members
 - **Networking**: Tailscale mesh
 
 ## Project landscape
@@ -229,10 +270,11 @@ When working on a project tagged with a client name:
 
 ## Harness-agnostic principles
 
-This context is designed to work with any AI coding tool:
-- Claude Code, Cursor, Aider, Open WebUI, Charmbracelet Mods/Crush
-- Pi Coding Agent, Mistral Vibe, Antigravity
-- Any tool that accepts a system prompt or reads a markdown context file
+Supported harnesses (2026-09-01) — Cursor and Aider were dropped; do not
+re-add adapters for them:
+- Claude Code, Antigravity, OpenCode, Mistral Vibe, Crush, Pi Coding Agent
+- Open WebUI, Charmbracelet Mods, or any tool that takes a system prompt string
+- Any other tool that reads `AGENTS.md`, which is the de facto convention
 
 The canonical source is always `.context/AGENT.md` (root) and `.context/PROJECT.md` (per-project).
 Derived files are committed (see *How context propagates* below) so a `git pull` on any host yields full agent context with no setup.
@@ -244,15 +286,29 @@ Canonical sources of truth:
 - Project: `<repo>/.context/PROJECT.md` (per-repo)
 
 Derived files (committed, regenerated by `task context:sync`):
-- `CLAUDE.md`, `AGENTS.md`, `.cursorrules`, `.aider.conventions.md`,
-  `.context/system-prompt.txt`
+- `CLAUDE.md`, `AGENTS.md`, `.context/system-prompt.txt`
+
+Repos still carrying `.cursorrules`, `.aider.conventions.md` or
+`.aider.conf.yml` are stale: nothing regenerates them. Delete them the next time
+you touch the repo, along with their entries in that repo's `task check`
+assertion.
 
 Workflow:
 1. Edit a canonical file. Run `task context:sync`. Commit canonical and
    derived together. Push.
-2. On any other host, `git pull` brings both. Claude Code (tree-walking)
-   uses `CLAUDE.md`; Crush / Pi / Antigravity (cwd-only) use `AGENTS.md`;
-   Cursor uses `.cursorrules`; Aider uses `.aider.conventions.md`.
+2. On any other host, `git pull` brings both. Which file a harness reads does
+   NOT split cleanly by lookup strategy, so do not reason from the strategy:
+   - `CLAUDE.md` — Claude Code (walks up the tree)
+   - `AGENTS.md` — Crush, Pi, Antigravity (cwd-only), OpenCode (project root,
+     global at `~/.config/opencode/AGENTS.md`), and Mistral Vibe, which **walks
+     up** from cwd and takes the first `AGENTS.md` it finds
+     (user-level `~/.vibe/AGENTS.md`)
+   - `.context/system-prompt.txt` — Open WebUI, Mods, raw API calls; not read by
+     any harness, it is for pasting
+
+   Vibe tree-walks for `AGENTS.md`, so "tree-walkers use CLAUDE.md" is false.
+   Each repo's `AGENTS.md` embeds the canonical and is the first one found from
+   inside that repo, so this works — but by construction, not by luck.
 3. `task check` runs `context:sync` then asserts `git status --porcelain`
    is empty over the derived files (catches both modified-tracked drift
    and missing-untracked adapters). A drift fails the check with a
@@ -263,7 +319,20 @@ unconditionally on every host, every harness.
 
 ## Engineering Skills
 
-Shared engineering skills live in the **`mathias/skills`** repo (`git.d-ma.be/mathias/skills`). Clone it to `~/dev/skills/` and run `SKILLS_CHECKOUT_DIR="$PWD" bash install.sh` there to wire every skill into your harnesses (Claude Code, Crush, Antigravity, Mistral Vibe) as native, on-demand skills. (Use `install.sh`, not `task install` — the latter is currently broken, skills#7.) Load at task start — not "on demand" but on schedule, before writing code. Browse `~/dev/skills/SKILLS_INDEX.md` for the full list.
+Shared engineering skills live in the **`mathias/skills`** repo (`git.d-ma.be/mathias/skills`). Load at task start — not "on demand" but on schedule, before writing code. Browse `SKILLS_INDEX.md` for the full list.
+
+**Claude Code** installs the repo as a plugin from the marketplace the same repo hosts. That path also carries the `secret-guard` and `pre-task-ritual` hooks and the brain/gitea/infra MCP servers, which symlinks cannot:
+
+```
+/plugin marketplace add https://git.d-ma.be/mathias/skills.git
+/plugin install skills@mathias
+```
+
+Skills are **namespaced** under Claude Code: load `tdd` as `skills:tdd`. The trigger table below uses bare names — prefix them.
+
+**Crush, Pi and OpenCode** have no plugin system and are wired by `install.sh` as one directory symlink per harness via `~/.agents/skills`. Do not clone the checkout into `~/dev`: that folder is iCloud-shared between the Macs and spans two path roots (`/Users/mathias` vs `/home/mathias` on koala), so a checkout there is a git working tree with two concurrent writers, and any absolute symlink stored in it is broken on one side by construction (skills#23). Leave `SKILLS_CHECKOUT_DIR` at its host-local default.
+
+Check a host with `task doctor` in the skills repo; it also runs automatically at session start via the plugin.
 
 **Skill trigger table — load before starting, not after getting stuck:**