The Canvas template-deploy path returned HTTP 500 with raw pq error
when a user clicked a template card twice in quick succession. Root
cause: migration 20260506000000 added the partial-unique index
`workspaces_parent_name_uniq` on (COALESCE(parent_id, sentinel), name)
WHERE status != 'removed' to close TOCTOU on /org/import (#2872). The
org-import handler resolves the constraint via ON CONFLICT DO NOTHING
+ idempotent re-select. The Canvas Create handler did not — it
bubbled the pq violation as a generic 500.
Fix: auto-suffix the user-typed name on collision via a small retry
helper that pins on SQLSTATE 23505 + constraint name (so unrelated
unique indexes still fail loud), retries with " (2)", " (3)" up to
N=20, and threads the actually-persisted name back into the response
+ broadcast payload (so the canvas displays what the DB actually
holds). Exhaustion maps to a clean 409 Conflict instead of a 500.
#2872 protection is preserved unchanged — the index stays in place,
and /org/import's ON CONFLICT path is unaffected. The bundle-import
INSERT (handlers/bundle.go) is a separate code path and is not
touched here; if it surfaces the same UX issue a follow-up can adopt
the same helper.
Verification (against running localhost:8080 platform):
Three back-to-back POSTs with name="ManualVerify-1778459812":
POST #1 -> 201, id=db2dacf7-…, persisted name="ManualVerify-1778459812"
POST #2 -> 201, id=f468083d-…, persisted name="ManualVerify-1778459812 (2)"
POST #3 -> 201, id=5f5ae905-…, persisted name="ManualVerify-1778459812 (3)"
Log lines: "name collision auto-suffix \"…\" -> \"… (N)\""
Tests:
- workspace_create_name_test.go — 4 unit tests via sqlmock pin the
retry contract (happy path no-suffix, single-collision -> " (2)",
non-retryable error pass-through, exhaustion -> errWorkspaceNameExhausted).
- workspace_create_name_integration_test.go — 2 real-Postgres tests
(build tag `integration`) confirm the partial-unique index
behaviour AND the WHERE status != 'removed' tombstone exemption.
- Watch-it-fail confirmed: temporarily removing the
`fmt.Sprintf("%s (%d)", baseName, attempt+1)` candidate-naming
line makes TestInsertWorkspaceWithNameRetry_SecondAttemptSuffixed
fail with the expected argument-mismatch from sqlmock.
Pre-existing test failures in handlers/ (TestExecuteDelegation_…,
TestMCPHandler_CommitMemory_GlobalScope_Blocked) reproduce on
unmodified staging and are NOT caused by this change.
