fix(core): resolve relative directories during V1 migration - #57618

Issue for this PR

Fixes #57602

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Problem. Old ACP sessions in the V1 session table can have directory = '.'. The V1→V2 migration copies that value into session_v2, then reads it back through directoryColumn, which throws Path is not absolute: .. The transaction rolls back along with the cursor update, so the migration retries the same row on every launch and never finishes.

Change. Before the copy, a directory that isn't a stored absolute path is replaced with the session's project worktree. A relative V1 directory was relative to the ACP process's working directory at the time, which we can't recover, so the worktree is the best available stand-in. The original V1 row is left unchanged.

 for each V1 session (newest first)
   pick projectID (missing project → global)
+  if directory is empty or a stored absolute path
+    keep it
+  else
+    use the project worktree (or "" if the worktree isn't absolute either)
+    log "Replaced relative V1 session directory"
   copy row into session_v2 with that directory
   read it back through directoryColumn   ← used to throw here

The migration and directoryColumn share one check, so they can't drift apart:

 database/path.ts
-  absolute(input)            # private: normalize + validate, throw if relative
+  storedAbsolutePath(input)  # exported: normalized path, or undefined if relative
+  absolute(input)            # throws when storedAbsolutePath returns undefined
 database/v1-migration.bun.ts
+  uses storedAbsolutePath for the session directory and the worktree

storedAbsolutePath normalizes backslashes the same way the column does, so Windows paths like C:\repo are still kept on Windows hosts.

Out of scope

• importNextDatabase copies directories from opencode-next.db without this check. That database has validated paths on write since it was created, so it's left alone here.
• The path (subpath) column is copied unchanged. Old ACP sessions predate that column, so it should be empty for the affected rows.

How did you verify your code works?

From packages/core on macOS:

bun test test/v1-migration.test.ts test/database-migration.test.ts   # 54 pass, 0 fail
bun test test/database.test.ts test/database-drizzle.test.ts test/database-migration.test.ts test/file-access-path.test.ts   # 51 pass, 0 fail
bun typecheck

New tests cover ., src, Windows-style and UNC worktrees, absolute directories that must be kept, empty directories, a non-absolute worktree, and . in a session whose project is missing. With the fix reverted, the relative-directory cases fail. The Windows-host behavior (backslash paths kept) was checked with a probe script that sets process.platform, not on a Windows machine.

Screenshots / recordings

No UI changes.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

Added by the opencode bot (AI-generated).

Related: #54736, #54009