diff --git a/lib/db/migrations/0005_free_tier.sql b/lib/db/migrations/0005_free_tier.sql
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+-- Migration: Free-tier cost routing (Task #27)
+-- Adds generosity pool store, grant audit log, and free-tier tracking columns.
+
+-- ── timmy_config ─────────────────────────────────────────────────────────────
+-- Key/value store for Timmy's internal config (e.g. generosity_pool_sats).
+
+CREATE TABLE IF NOT EXISTS timmy_config (
+  key         TEXT PRIMARY KEY,
+  value       TEXT NOT NULL,
+  updated_at  TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+-- ── nostr_identities: free-tier absorption columns ───────────────────────────
+-- Rolling daily budget: how many sats Timmy has subsidised for this identity
+-- today; resets when absorbed_reset_at is older than 24 h.
+
+ALTER TABLE nostr_identities
+  ADD COLUMN IF NOT EXISTS sats_absorbed_today INTEGER NOT NULL DEFAULT 0,
+  ADD COLUMN IF NOT EXISTS absorbed_reset_at   TIMESTAMPTZ NOT NULL DEFAULT NOW();
+
+-- ── jobs: free-tier tracking columns ─────────────────────────────────────────
+-- free_tier=TRUE  → Timmy absorbed part or all of this job's cost from the pool.
+-- absorbed_sats   → how many sats Timmy absorbed (NULL or 0 for fully-paid jobs).
+
+ALTER TABLE jobs
+  ADD COLUMN IF NOT EXISTS free_tier      BOOLEAN  NOT NULL DEFAULT FALSE,
+  ADD COLUMN IF NOT EXISTS absorbed_sats  INTEGER;
+
+-- ── sessions: nostr identity FK ──────────────────────────────────────────────
+-- Added in task #26; included here for completeness in migration-driven deploys.
+
+ALTER TABLE sessions
+  ADD COLUMN IF NOT EXISTS nostr_pubkey TEXT
+    REFERENCES nostr_identities(pubkey);
+
+-- ── free_tier_grants ─────────────────────────────────────────────────────────
+-- Audit log: one row each time Timmy absorbs cost on behalf of an identity.
+
+CREATE TABLE IF NOT EXISTS free_tier_grants (
+  id                  TEXT PRIMARY KEY,
+  pubkey              TEXT NOT NULL REFERENCES nostr_identities(pubkey),
+  request_hash        TEXT NOT NULL,
+  sats_absorbed       INTEGER NOT NULL,
+  pool_balance_after  INTEGER NOT NULL,
+  created_at          TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE INDEX IF NOT EXISTS idx_free_tier_grants_pubkey
+  ON free_tier_grants(pubkey);