feat(db): enforce globally unique issue prefixes and identifiers

Derive issue_prefix from first 3 letters of company name with
deterministic suffixes on collision. Migration rebuilds existing
prefixes, reassigns issue numbers, and adds unique indexes.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/db/src/migrations/0017_tiresome_gabe_jones.sql

@@ -0,0 +1,51 @@
+DROP INDEX "issues_company_identifier_idx";--> statement-breakpoint
+
+-- Rebuild issue prefixes to be company-specific and globally unique.
+-- Base prefix is first 3 letters of company name (A-Z only), fallback "CMP".
+-- Duplicate bases receive deterministic letter suffixes: PAP, PAPA, PAPAA, ...
+WITH ranked_companies AS (
+  SELECT
+    c.id,
+    COALESCE(NULLIF(SUBSTRING(REGEXP_REPLACE(UPPER(c.name), '[^A-Z]', '', 'g') FROM 1 FOR 3), ''), 'CMP') AS base_prefix,
+    ROW_NUMBER() OVER (
+      PARTITION BY COALESCE(NULLIF(SUBSTRING(REGEXP_REPLACE(UPPER(c.name), '[^A-Z]', '', 'g') FROM 1 FOR 3), ''), 'CMP')
+      ORDER BY c.created_at, c.id
+    ) AS prefix_rank
+  FROM companies c
+)
+UPDATE companies c
+SET issue_prefix = CASE
+  WHEN ranked_companies.prefix_rank = 1 THEN ranked_companies.base_prefix
+  ELSE ranked_companies.base_prefix || REPEAT('A', ranked_companies.prefix_rank - 1)
+END
+FROM ranked_companies
+WHERE c.id = ranked_companies.id;--> statement-breakpoint
+
+-- Reassign issue numbers sequentially per company to guarantee uniqueness.
+WITH numbered_issues AS (
+  SELECT
+    i.id,
+    ROW_NUMBER() OVER (PARTITION BY i.company_id ORDER BY i.created_at, i.id) AS issue_number
+  FROM issues i
+)
+UPDATE issues i
+SET issue_number = numbered_issues.issue_number
+FROM numbered_issues
+WHERE i.id = numbered_issues.id;--> statement-breakpoint
+
+-- Rebuild identifiers from normalized prefix + issue number.
+UPDATE issues i
+SET identifier = c.issue_prefix || '-' || i.issue_number
+FROM companies c
+WHERE c.id = i.company_id;--> statement-breakpoint
+
+-- Sync counters to the largest issue number currently assigned per company.
+UPDATE companies c
+SET issue_counter = COALESCE((
+  SELECT MAX(i.issue_number)
+  FROM issues i
+  WHERE i.company_id = c.id
+), 0);--> statement-breakpoint
+
+CREATE UNIQUE INDEX "companies_issue_prefix_idx" ON "companies" USING btree ("issue_prefix");--> statement-breakpoint
+CREATE UNIQUE INDEX "issues_identifier_idx" ON "issues" USING btree ("identifier");

packages/db/src/migrations/meta/_journal.json

@@ -120,6 +120,13 @@
       "when": 1771955900000,
       "tag": "0016_agent_icon",
       "breakpoints": true
+    },
+    {
+      "idx": 17,
+      "version": "7",
+      "when": 1771883888199,
+      "tag": "0017_tiresome_gabe_jones",
+      "breakpoints": true
     }
   ]
 }