Deedglass MCP server

An agent said it updated 1 row. Postgres changed 301.

<!-- description:summary (docs/description.json; docs/description_test.go checks it) --> Deedglass sits between AI agents and the systems they change. Rules decide each tool call, a check compares what the system really changed with what the agent reported (Claimed, Checked or Proven; Matches, Doesn't match or Can't check), and each result is sealed as a signed record anyone can check offline. It can undo the rows an action changed.

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An agent was asked to mark order 42 as shipped. It ran one UPDATE and its tool reported 1 row. A legacy trigger shipped 300 more orders in the same transaction. This is the real output of the Quickstart's last step on 2026-10-14 (shortened where you see …):

$ npx -y deedglass init --trigger
…
✕ UPDATE order 42         Proven · Doesn't match · Postgres changed 301 rows in public.orders. The agent reported 1.
  expected   UPDATE 1 row in public.orders where id = 42 · sets status
  observed   UPDATE 301 rows in public.orders · 300 outside id = 42
…
✓ Trigger off             orders_ship_open_batch dropped
✓ Undo preview            Undo available · 301 rows in public.orders · 301 updates
    policy   undo-needs-approval · a person countersigns first

The agent's log says 1 row. Deedglass read Postgres's own change log for that transaction, found 301, sealed the difference as a record, and planned an undo from those rows that runs only after a person countersigns.

A real run of make demo-hero (commit 97a524c, 2026-10-14), each line shown at the time it printed. Source: docs/assets/demo-hero.cast.json, drawn by scripts/demo/cast2svg.mjs.

Four ways in

Shortened. The full README is on GitHub.