docs: add living system design

[jgpruitt]

Summary

• replace historical ADRs with indexed, living design documentation
• document authorization, principals, spaces, migrations, embeddings, field projection, and harness integrations
• clarify that default CLI search output is locally projected

Verification

• ./bun run check
• ./bun run check:full (blocked: local PostgreSQL at 127.0.0.1:5432 lacks the postgres role; the repository me-postgres container could not start because that port is occupied)

[Copilot]

Pull request overview

This PR shifts architectural documentation from historical ADRs to a set of indexed, “living” design docs under design/, and updates the CLI docs to clarify that --select affects local presentation (not server-side response shaping).

Changes:

• Add a new design/ documentation set covering spaces/provisioning, principals/auth, API-key scoping, harness integrations, migrations/versioning, embeddings, and presentation/field projection.
• Convert existing ADR-styled design docs into living references (remove ADR metadata sections and reframe as invariants/constraints).
• Update me memory search --select documentation to state the default text view is locally projected.

Reviewed changes

Copilot reviewed 19 out of 19 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
docs/cli/me-memory.md	Clarifies that default text search output is locally projected rather than requested as a partial response.
design/README.md	Adds an index for the living design documentation set.
design/spaces.md	Documents space identity, provisioning defaults, custom provisioning flags, invitations, and lifecycle.
design/principal-model.md	Defines principal vs member terminology and the user/group/service-account model (including rationale for removing agent principals).
design/memory-authorization.md	Documents membership vs data access, grant levels, effective access computation, and delegation model.
design/restricted-api-keys.md	Documents restricted key declarations as a server-enforced ceiling and their effective-authority intersection rules.
design/harness-integrations.md	Describes harness integration layering, directory-scoped activation policy, and the shared runtime contract.
design/harnesses/claude.md	Documents Claude Code adapter behavior for env injection, MCP, and capture hooks.
design/harnesses/opencode.md	Documents OpenCode adapter behavior for env injection, MCP, and capture triggers.
design/harnesses/codex.md	Documents Codex adapter command-rewrite hook behavior and provider constraints.
design/database-migrations-and-versioning.md	Documents schema families, incremental vs idempotent migrations, startup reconciliation, and signature-guarded functions.
design/embedding-queue-and-worker.md	Documents per-space embedding queues, claiming/retries, staleness, and operational reporting.
design/field-projection-and-format-selection.md	Documents CLI/MCP presentation-only selection/format behavior and selector rules.
design/semantic-search-scoring.md	Reframes semantic score behavior as invariants/constraints (cosine similarity, threshold bounds).
design/hnsw-filtered-semantic-search.md	Reframes filtered semantic search behavior and constraints around iterative scans.
design/fulltext-bm25-scoring.md	Reframes BM25 positive-match invariant and its role in hybrid search.
design/hybrid-rrf-scoring.md	Reframes RRF fusion model, determinism constraints, and tuning boundaries.
design/jsonpath-metadata-predicates.md	Reframes metaPredicate as a PostgreSQL-native filter with documented constraints and compatibility requirements.
adr/README.md	Removes the ADR index in favor of the new living design documentation.

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[Copilot]

Pull request overview

Copilot reviewed 21 out of 21 changed files in this pull request and generated no new comments.