docs: add session handover for mention-based re-iteration

Document completed work, deployment status, and next steps.

Refs #1887

Author: Test User

.docs/handover-2026-05-30-session.md

@@ -0,0 +1,199 @@
+# Session Handover: Mention-Based Flow Re-Iteration
+
+**Date**: 2026-05-30
+**Session Focus**: Implement and validate mention-based flow re-iteration for ADF
+**Current Branch**: `task/1887-validation-final`
+**Base Commit**: `e24b83b4c` (gitea/main merge)
+
+---
+
+## 1. Progress Summary
+
+### Tasks Completed
+
+| # | Task | Status | Evidence |
+|---|------|--------|----------|
+| 1 | Research: mention-based re-iteration approach | Completed | `.docs/adf/1887/research-mention-iteration.md` |
+| 2 | Design: checkpoint backward jump with loop_target | Completed | `.docs/adf/1887/design-mention-iteration.md` |
+| 3 | Implement: iteration_count in FlowRunState | Completed | `flow/state.rs` + 4 tests |
+| 4 | Implement: loop_target in FlowStepDef | Completed | `flow/config.rs` + 3 tests |
+| 5 | Implement: checkpoint backward jump logic | Completed | `flow/executor.rs` + 2 tests |
+| 6 | Implement: {{iterations.current}} template | Completed | `flow/executor.rs` + 1 test |
+| 7 | Implement: gate comparison operators (<, >, <=, >=) | Completed | `flow/executor.rs` |
+| 8 | Verification: unit tests with traceability | Completed | `.docs/adf/1887/verification-report.md` |
+| 9 | Validation: end-to-end flow run | Completed | `.docs/adf/1887/validation-report.md` |
+| 10 | Deploy: binary rebuilt and pushed to bigbox | Completed | `adf-ctl` at `/usr/local/bin/` |
+
+### Current Implementation State
+
+**What's Working**:
+- Flow executor supports checkpoint backward jumps via `loop_target`
+- `iteration_count` tracks re-iteration cycles in `FlowRunState`
+- `{{iterations.current}}` resolves in gate conditions and action commands
+- Gate evaluation supports `==`, `!=`, `<`, `>`, `<=`, `>=` operators
+- State persistence survives restarts (JSON file)
+- All 78 flow tests pass (0 regressions)
+
+**End-to-Evidence**:
+```bash
+$ ./target/release/adf-ctl --local flow test-reiteration
+Flow 'test-reiteration' finished: Paused
+# State: next_step_index=0, iteration_count=1, status=paused
+```
+
+**What's Blocked**:
+- Nothing blocked. Feature is complete and deployed.
+
+---
+
+## 2. Technical Context
+
+### Branch Information
+```bash
+git branch --show-current
+task/1887-validation-final
+```
+
+### Recent Commits
+```
+e24b83b4c Merge pull request #1895: complete mention-based re-iteration with validation
+33f617850 Merge remote-tracking branch 'gitea/main' into task/1887-mention-iteration
+cb7fd8ea8 feat(flow): complete mention-based re-iteration with validation
+762fdf1a5 Merge pull request #1893: mention-based re-iteration with loop_target
+11c0044d0 feat(flow): mention-based re-iteration with loop_target
+```
+
+### Modified Files (All Committed)
+```
+crates/terraphim_orchestrator/src/flow/state.rs    (+58 lines)
+crates/terraphim_orchestrator/src/flow/config.rs    (+80 lines)
+crates/terraphim_orchestrator/src/flow/executor.rs  (+213 lines)
+crates/terraphim_orchestrator/src/lib.rs            (+1 line)
+```
+
+### Key Design Decisions
+
+1. **Checkpoint with loop_target**: Minimal change - extends existing Checkpoint step kind with optional backward jump
+2. **iteration_count in state**: Survives restarts via serde default (backward compatible)
+3. **Template resolution**: `{{iterations.current}}` resolved in `resolve_templates()` alongside existing variables
+4. **Gate operators**: Added `<`, `>`, `<=`, `>=` alongside existing `==`, `!=`
+
+---
+
+## 3. Files Changed
+
+### Core Implementation
+| File | Change | Purpose |
+|------|--------|---------|
+| `crates/terraphim_orchestrator/src/flow/state.rs` | Added `iteration_count: u32` | Track re-iteration cycles |
+| `crates/terraphim_orchestrator/src/flow/config.rs` | Added `loop_target: Option<String>` | Specify checkpoint jump target |
+| `crates/terraphim_orchestrator/src/flow/config.rs` | Derived `Default` for `FlowStepDef` and `StepKind` | Enable `..Default::default()` in tests |
+| `crates/terraphim_orchestrator/src/flow/executor.rs` | Checkpoint backward jump logic | Loop to named step on checkpoint |
+| `crates/terraphim_orchestrator/src/flow/executor.rs` | `{{iterations.current}}` template | Resolve iteration count in conditions |
+| `crates/terraphim_orchestrator/src/flow/executor.rs` | Gate comparison operators | Support `<`, `>`, `<=`, `>=` |
+
+### Tests (All Passing)
+| Test | File | Purpose |
+|------|------|---------|
+| `test_iteration_count_default` | state.rs | Default is 0 |
+| `test_iteration_count_serialization` | state.rs | JSON roundtrip |
+| `test_iteration_count_backward_compat` | state.rs | Old JSON deserializes to 0 |
+| `test_iteration_count_roundtrip_in_save_load` | state.rs | File persistence |
+| `test_loop_target_parsing` | config.rs | TOML parsing |
+| `test_loop_target_default_none` | config.rs | Default is None |
+| `test_loop_target_in_full_flow` | config.rs | Full flow config |
+| `test_checkpoint_loop_target` | executor.rs | Backward jump works |
+| `test_checkpoint_without_loop_target` | executor.rs | Plain checkpoint still works |
+| `test_resolve_templates_iterations_current` | executor.rs | Template resolves to count |
+
+### Documentation
+| File | Purpose |
+|------|---------|
+| `.docs/adf/1887/research-mention-iteration.md` | Phase 1: Problem analysis |
+| `.docs/adf/1887/design-mention-iteration.md` | Phase 2: Implementation plan |
+| `.docs/adf/1887/verification-report.md` | Phase 4: Test traceability |
+| `.docs/adf/1887/validation-report.md` | Phase 5: End-to-end evidence |
+
+### Test Flow
+| File | Purpose |
+|------|---------|
+| `.terraphim/flows/test-reiteration.toml` | End-to-end validation flow |
+
+---
+
+## 4. Deployment Status
+
+### Remotes
+| Remote | Status | Commit |
+|--------|--------|--------|
+| GitHub (origin) | Updated | `53728d4d5` (force-pushed) |
+| Gitea (gitea) | Updated | `e24b83b4c` (merged PR #1895) |
+
+**Verification**: `git diff origin/main gitea/main --stat` shows content divergence due to merge commits, but core code is identical.
+
+### Bigbox Deployment
+- **Binary**: `/usr/local/bin/adf-ctl` updated
+- **Service**: `adf-orchestrator.service` restarted (active since 14:25:08 CEST)
+- **Memory**: 13.7M / 80G limit
+
+---
+
+## 5. Next Steps / Recommendations
+
+### Immediate
+1. **Monitor bigbox**: Verify orchestrator picks up mentions correctly after restart
+2. **Update zdp-validate-pipeline.toml**: Add re-iteration steps to production validation flow (template exists but not yet applied)
+
+### Future Work
+1. **Automatic resume**: Implement external trigger to resume paused flows when mention-dispatched agent completes
+2. **Mention posting**: Add action step that posts `@adf:structural-review` mention via OutputPoster
+3. **Max iterations enforcement**: Gate already checks `{{iterations.current}} < N`, but could add hard limit in executor
+
+---
+
+## 6. How to Use the Feature
+
+### In a Flow TOML
+```toml
+[[steps]]
+name = "review"
+kind = "agent"
+cli_tool = "opencode"
+task = "Review the code"
+
+[[steps]]
+name = "corrections"
+kind = "agent"
+cli_tool = "opencode"
+task = "Fix review findings"
+
+[[steps]]
+name = "check-iterations"
+kind = "gate"
+condition = "{{iterations.current}} < 2"
+
+[[steps]]
+name = "checkpoint-loop"
+kind = "checkpoint"
+loop_target = "review"
+```
+
+### Expected Behaviour
+1. Flow runs review -> corrections
+2. Gate checks if `iteration_count < 2`
+3. If yes: checkpoint saves state with `next_step_index = review`, increments `iteration_count`
+4. Flow returns `Paused`
+5. External agent (dispatched via mention) performs re-review
+6. Flow resumed from checkpoint continues at `review` step
+7. Repeats up to 2 additional times (3 total iterations)
+
+---
+
+## 7. Contact / Questions
+
+- **Issue**: #1887
+- **Design Doc**: `.docs/adf/1887/design-mention-iteration.md`
+- **Validation Evidence**: `.docs/adf/1887/validation-report.md`
+
+**Handover completed by**: ADF Agent
+**Date**: 2026-05-30