feat(manifest): docs block and repo configure --ai writes the project MCP config #2590

Goal

Make an inheriting project get its own documentation index and MCP entry from one configuration step.

Background

'Automatically get their own MCP server' means one shared server and per-project indexes, not a separate install. A manifest docs: block declares roots and exclusions; basectl repo configure --ai writes the project-scoped .mcp.json entry. AGENTS.md forbids repo-level personal Codex settings, so other providers get printed guidance rather than committed config.

Next-release planning review of 2026-10-14/15 against main at 7faf6dfb. Tracking: #2555.

Prerequisites: #2588, #2589.

Scope

• Manifest docs: block (roots, exclude) with validation and finding IDs.
• repo configure --ai writes .mcp.json invoking basectl mcp serve --project <name>; repo check verifies it.
• basectl docs index for any managed project; per-project cache location.
• Pilot validation on bankbuddy and blend.

Acceptance Criteria

• A fresh managed project gets a working index and MCP entry from repo configure --ai.
• Declared roots are enforced by the security: read-only MCP/index threat model, root allowlist, and untrusted-content framing #2589 rules.
• repo check flags a missing or drifted entry.

Validation

BASE_CLI_SOURCE_DIR=../base-cli/lib/python \
PYTHONPATH=../base-cli/lib/python:lib/python:cli/python \
python -m pytest cli/python/base_projects/tests <new manifest docs tests>
git diff --check

Non-Goals

• No personal agent configuration in repositories.
• No per-project server install.

Project Fields

• Status: Backlog
• Priority: P2
• Area: Manifest
• Initiative: Agentic Coding Platform
• Size: M
• Milestone: v1.13.0
• Category: enhancement

Agent Assignment

Assignee: codeforester. Blocked on #2588 and #2589.

Plan revision (2026-10-16)

Keep this in v1.13.0. Add #2600 to the prerequisites in addition to #2588 and #2589, and require #1613's manifest schema before accepting the docs: block. The project configuration must fail closed on missing/invalid roots, preserve the #2589 redaction and untrusted-content rules, and report the exact server command, project identity, and index provenance that it writes. Pilot wiring is validation work for #2592/#2593, not permission to bypass their controller and evidence prerequisites.