Fix repeated default registry contract tests

docs/logs/engineering-log.md

@@ -88,6 +88,22 @@
   the full harness package passes in normal and race modes; and
   `./scripts/test-regression.sh` passes normal, full race, and `coveragegate`
   at 85.6% with zero uncovered functions.
+## 2026-07-30 (Default Workspace Registry Test Isolation — Issue #1042)
+
+- Symptom: `TestDefaultRegistry_Functions` fails on its second in-process
+  invocation with `workspace: implementation already registered`.
+- Cause: every invocation registers the fixed
+  `test-default-impl-unique-12345` name in the intentionally persistent package
+  registry.
+- Planned fix: assign each invocation a process-local atomic suffix while
+  retaining the same-name duplicate assertion inside that invocation.
+- Verification contract: focused normal/race `-count=100`, workspace
+  normal/race, and full repository normal/race/coverage gate.
+- Result: the focused normal/race tests passed at `-count=100`, the complete
+  workspace package passed normal/race at `-count=5`, and
+  `./scripts/test-regression.sh` passed with 85.6% total coverage and zero
+  uncovered functions.
+
 ## 2026-07-30 (Workflow Subscription Cancellation Test — Issue #1035)
 
 - Symptom: the full race gate failed in

docs/logs/long-term-thinking-log.md

@@ -74,6 +74,21 @@
   stress plus the full repository gate.
 - Guardrails: issue-first isolated worktree, deterministic red evidence,
   test-only synchronization, no production lifetime change, and no sleeps.
+## 2026-07-30 (Default Workspace Registry Test Isolation — Issue #1042)
+
+- Command intent: clear the repeatable workspace-package blocker discovered by
+  the mandatory post-merge coverage gate.
+- User intent: do not merge the cron/callback GUI work over any red accepted
+  baseline, even when the failure is in an unrelated test fixture.
+- Success definition: every in-process invocation owns a unique registry name,
+  retains the duplicate-registration contract, and passes repeated/race/full
+  gates.
+- Guardrails: issue-first isolated worktree, test-only atomic identity, no
+  production reset/unregister or weakened assertion.
+- Outcome: the atomic invocation identity retained every public registry
+  assertion and cleared focused stress, package stress, normal, race, and
+  coverage verification.
+
 ## 2026-07-30 (Workflow Subscription Cancellation Test — Issue #1035)
 
 - Command intent: clear the race-gate blocker exposed while verifying the

docs/plans/2026-07-30-issue-1042-default-registry-repeat-impact-map.md

@@ -0,0 +1,66 @@
+# Cross-Surface Impact Map: Issue #1042 Default Registry Repeatability
+
+## Task
+
+- Task / issue: isolate repeated default-registry test invocations, #1042.
+- Plan: `2026-07-30-issue-1042-default-registry-repeat-plan.md`.
+- Owner: Codex.
+- Status: implemented and fully verified; merge pending.
+
+## Current Ownership, Callers, and Data Flow
+
+- Entry: `TestDefaultRegistry_Functions`.
+- Source of truth: package-level `defaultRegistry`; top-level
+  `Register/List/New` delegate to it.
+- Search: all `workspace.Register`, default-registry tests, init registration,
+  and reset/unregister APIs.
+- Conclusion: production correctly retains registrations; only the fixed test
+  identity incorrectly assumes one invocation per process.
+
+## Config, API, CLI, and Tools
+
+- Config/env/defaults: none.
+- API/CLI/wire/tools: production top-level registry API remains exercised.
+- Errors: retain explicit `ErrAlreadyExists` and provisioning checks.
+
+## Persistence and Compatibility
+
+- State: process-local test registry only.
+- Schemas/migrations/caches: none.
+- Compatibility: no runtime change.
+
+## Lifecycle, Security, and Reliability
+
+- Concurrency: process-local atomic counter assigns invocation ownership.
+- Auth/privacy/secrets: none.
+- Failure/recovery: assertion output includes the generated name.
+
+## Product and Integration Surfaces
+
+- Server/TUI/web/macOS/providers: none.
+- Automation: normal, race, repeated, and coverage gates become deterministic.
+- UX/accessibility: none.
+
+## Deployment and Operations
+
+- Deployment/migration/flags: none.
+- Rollback: revert if first/duplicate registration is no longer distinguished.
+- Operator docs: none.
+
+## Regression Tests
+
+- Red: focused `-count=2` fixed-name failure.
+- Green: focused normal/race `-count=100`.
+- Controls: List contains the invocation's name; New provisions exactly its
+  factory; duplicate still fails.
+- Full: workspace normal/race and `./scripts/test-regression.sh`.
+
+## Documentation and Handoff
+
+- Update engineering log, long-term log, plan, impact map, and plans index.
+- No public docs.
+
+## Warning Check
+
+- All runtime/product surfaces are explicitly unaffected because the change is
+  confined to fixture identity.

docs/plans/2026-07-30-issue-1042-default-registry-repeat-plan.md

@@ -0,0 +1,61 @@
+# Plan: Make the Default Registry Contract Test Repeatable
+
+## Context
+
+- Governing GitHub issue: #1042.
+- Problem: `TestDefaultRegistry_Functions` registers a fixed name in a
+  process-global registry, so the second `-count` invocation fails before it
+  can test its own duplicate-registration contract.
+- User impact: an unrelated workspace package failure blocks the accepted
+  cron/callback GUI merge chain.
+- Constraint: keep production registry semantics and every top-level API
+  assertion unchanged.
+
+## Scope
+
+- In scope: allocate a collision-free name for each test invocation.
+- Out of scope: production reset/unregister APIs, registry ownership, package
+  serialization, and runtime behavior.
+
+## Documentation Contract
+
+- Feature status: test-only bug repair in implementation.
+- Public docs affected: none.
+- Evidence: engineering and long-term logs, plan, impact map, plans index.
+
+## Test Plan (TDD)
+
+- Red: existing focused test at `-count=2` fails deterministically on the second
+  invocation with `ErrAlreadyExists`.
+- Green: focused normal/race at `-count=100`; each invocation still asserts
+  first registration, duplicate rejection, listing, and provisioning.
+- Full: workspace normal/race and repository normal/race/coverage gate.
+
+## Cross-Surface Impact Map
+
+- See `2026-07-30-issue-1042-default-registry-repeat-impact-map.md`.
+
+## Implementation Checklist
+
+- [x] Create contract-complete bug #1042.
+- [x] Capture deterministic red evidence.
+- [x] Record registry ownership/search evidence.
+- [x] Write plan and impact map before code.
+- [x] Implement invocation-unique identity.
+- [x] Run focused stress and full gates.
+- [ ] Merge through a closing PR.
+
+## Verification
+
+- Focused normal and race tests passed at `-count=100`.
+- The complete workspace package passed normal and race tests at `-count=5`.
+- `./scripts/test-regression.sh` passed normal, race, and the 85.6% coverage
+  gate with zero uncovered functions.
+
+## Risks and Mitigations
+
+- Risk: unique names could stop testing duplicate rejection.
+- Mitigation: register the same invocation-local name twice and retain the
+  explicit `ErrAlreadyExists` assertion.
+- Risk: a timing-derived name could collide.
+- Mitigation: use a process-local atomic sequence, not wall-clock time.

docs/plans/INDEX.md

@@ -10,6 +10,8 @@
 - `2026-07-30-issue-1044-ask-status-race-impact-map.md` — Cross-surface impact map for Issue #1044.
 - `2026-07-30-issue-1039-worktree-containment-ci-plan.md` — Issue #1039 planned synchronization of live worktree containment assertions with terminal cleanup.
 - `2026-07-30-issue-1039-worktree-containment-ci-impact-map.md` — Cross-surface impact map for Issue #1039.
+- `2026-07-30-issue-1042-default-registry-repeat-plan.md` — Issue #1042 planned repeatable top-level workspace registry contract test.
+- `2026-07-30-issue-1042-default-registry-repeat-impact-map.md` — Cross-surface impact map for Issue #1042.
 - `2026-07-30-issue-1035-workflow-subscription-cancel-plan.md` — Issue #1035 planned deterministic workflow subscription-cancellation regression repair.
 - `2026-07-30-issue-1035-workflow-subscription-cancel-impact-map.md` — Cross-surface impact map for Issue #1035.
 - `2026-07-30-issue-1026-feedback-direct-publish-plan.md` — Issue #1026 attached-image, publish-by-default GitHub feedback intake (implemented and verified; promotion pending).

internal/workspace/workspace_test.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"sync"
+	"sync/atomic"
 	"testing"
 
 	"go-agent-harness/internal/workspace"
@@ -13,6 +14,8 @@ import (
 // Compile-time interface compliance check.
 var _ workspace.Workspace = (*mockWorkspace)(nil)
 
+var defaultRegistryTestSequence atomic.Uint64
+
 // mockWorkspace is a test implementation of the Workspace interface.
 type mockWorkspace struct {
 	mu              sync.Mutex
@@ -279,8 +282,9 @@ func TestRegistry_Concurrent(t *testing.T) {
 // --------------------------------------------------------------------------
 
 func TestDefaultRegistry_Functions(t *testing.T) {
-	// Use unique names to avoid conflicts with other tests sharing the default registry.
-	const implName = "test-default-impl-unique-12345"
+	// The default registry intentionally persists for the process lifetime, so
+	// each `-count` invocation must own a distinct name.
+	implName := fmt.Sprintf("test-default-impl-%d", defaultRegistryTestSequence.Add(1))
 
 	f, created := newMockFactory("http://harness.local", "/ws/default")
 	if err := workspace.Register(implName, f); err != nil {