[AZ-899] [AZ-900] [AZ-901] Baseline doc + retro gate + EVIDENCE_OUT fix

AZ-899: create _docs/02_document/architecture_compliance_baseline.md
seeded with 0 violations and the 2026-05-20 structural snapshot facts
(15 inventory entries, 0 import cycles, 5 contract files). Documents
the append-on-violation / mark-resolved-on-fix / snapshot-refresh
protocol so cumulative reviews can emit Baseline Delta sections.
Closes cycle-1 retro Top-3 #3 (third attempt).

AZ-900: codify LESSONS 2026-05-26 [process] in
.cursor/skills/autodev/flows/existing-code.md - Re-Entry After
Completion now hosts a Previous-Cycle Retro Existence Gate that
BLOCKS the cycle increment if no _docs/06_metrics/retro_*.md file
dated within [cycle_start, cycle_end] exists. Skipped on
state.cycle == 1. Presents Choose A (author retro) / B (stub +
leftover) / C (abort). state.md - Session Boundaries gains a
cross-reference bullet.

AZ-901: fix e2e/runner/conftest.py:56 EVIDENCE_OUT default - host
pytest now resolves <repo_root>/e2e-results/evidence/ instead of
/e2e-results/evidence (container-only path; crashed on macOS / non-
root Linux). Docker + Jetson harnesses unaffected (they pass
--evidence-out explicitly). Verified locally: 24 SKIPPED, exit 0,
evidence written. Closes leftover 2026-05-26_evidence_out_default_path.md.

Co-authored-by: Cursor <cursoragent@cursor.com>

.cursor/skills/autodev/flows/existing-code.md

@@ -326,7 +326,7 @@ After retrospective completes:
 **Re-Entry After Completion**
 State-driven: `state.step == done` OR Step 17 (Retrospective) is completed for `state.cycle` AND Step 16.5 verdict was `Released` or `Released-with-override`. A `Rolled-Back` cycle does NOT trigger Re-Entry — the user must explicitly invoke `/autodev` again.
 
-Action: The project completed a full cycle. Print the status banner and automatically loop back to New Task — do NOT ask the user for confirmation:
+Action: The project completed a full cycle. Before incrementing the cycle counter, run the **Previous-Cycle Retro Existence Gate** below. If the gate passes (or its `state.cycle == 1` early exit applies), print the status banner and automatically loop back to New Task — do NOT ask the user for confirmation:
 
 ```
 ══════════════════════════════════════
@@ -341,6 +341,58 @@ Set `step: 9`, `status: not_started`, and **increment `cycle`** (`cycle: state.c
 
 Note: the loop (Steps 9 → 17 → 9) ensures every feature cycle includes: New Task → Implement → Run Tests → Test-Spec Sync → Update Docs → Security → Performance → Deploy → Release → Retrospective. The cycle only completes (and loops back to Step 9) on a `Released` or `Released-with-override` verdict; rolled-back or aborted releases stop the cycle.
 
+---
+
+**Previous-Cycle Retro Existence Gate** (AZ-900, codifies LESSONS 2026-05-26 [process])
+
+Trigger: run this gate at the start of Re-Entry After Completion, BEFORE the `cycle: state.cycle + 1` increment in the state file.
+
+Early-exit: if `state.cycle == 1`, the gate is **skipped** — cycle 1 has no previous cycle whose retro could exist. (A greenfield → existing-code transition on first entry to Phase B falls in this branch.)
+
+Otherwise (`state.cycle >= 2`):
+
+1. **Compute the date range for the cycle just completing.**
+   - `cycle_start = ` modification date of the latest `_docs/03_implementation/implementation_report_*_cycle{state.cycle-1}.md` file. If no implementation report exists for the previous cycle (e.g. cycle was rolled back at Step 16.5), use the modification date of the latest `_docs/06_metrics/retro_*.md` file as a lower bound, or fall back to "yesterday" if neither exists.
+   - `cycle_end = ` today (the date at which the gate runs).
+2. **Glob for the retro file**: `_docs/06_metrics/retro_*.md`, parse the `YYYY-MM-DD` portion of each filename, and check whether **any** file's date lies in the inclusive range `[cycle_start, cycle_end]`.
+3. **If at least one retro file is in range** → gate PASSES → continue with the cycle increment.
+4. **If no retro file is in range** → gate BLOCKS → play the notification sound per `.cursor/rules/human-attention-sound.mdc` and present the Choose block below.
+
+```
+══════════════════════════════════════
+ RETRO MISSING for cycle <state.cycle>
+══════════════════════════════════════
+ No `_docs/06_metrics/retro_*.md` file dated
+ within [<cycle_start>, <cycle_end>] was found.
+ Per LESSONS 2026-05-26 [process], the cycle
+ must close with a retro before cycle <state.cycle+1>
+ can start.
+══════════════════════════════════════
+ A) Author the missing retro now (invoke
+    .cursor/skills/retrospective/SKILL.md in
+    cycle-end mode against cycle <state.cycle>,
+    then re-run this gate)
+ B) Stub a backfilled retro and proceed (file
+    a leftover entry under
+    _docs/_process_leftovers/<YYYY-MM-DD>_retro_backfill_cycle<N>.md
+    naming what data is missing; create
+    _docs/06_metrics/retro_<today>_backfill_cycle<N>.md
+    with the available data; then continue
+    the cycle increment)
+ C) Abort and ask the user
+══════════════════════════════════════
+ Recommendation: A — a real retro keeps
+ LESSONS.md honest; B is a last resort when
+ cycle data is genuinely unrecoverable.
+══════════════════════════════════════
+```
+
+- **On A** → invoke `.cursor/skills/retrospective/SKILL.md` in cycle-end mode with `cycle: state.cycle`. When it completes successfully, re-run the gate from step 1; on PASS, continue. If retrospective itself fails, follow standard Failure Handling (`protocols.md`).
+- **On B** → create the leftover entry and stub retro as documented in the option label, then continue with the cycle increment. Surface this in the Status Summary footer of the next session via the leftovers folder.
+- **On C** → STOP. Do not increment `cycle`. Leave `state.step == done` so the user re-invokes `/autodev` after writing the retro by hand.
+
+Gate scope: this gate fires ONLY in `existing-code` flow. `greenfield` has no cycle counter (single Done step). `meta-repo` has no cycle counter (its cadence is `monorepo-status` re-runs, not feature cycles).
+
 ## Auto-Chain Rules
 
 ### Phase A — One-time baseline setup

.cursor/skills/autodev/state.md

@@ -146,6 +146,10 @@ A **session boundary** is a transition that explicitly breaks auto-chain. Which
 
 **Invariant**: a flow row without the `Session boundary` marker auto-chains unconditionally. Missing marker = missing boundary.
 
+**Cross-reference — content gates that can also stop auto-chain.** Some flow files declare additional gates that block a transition even when the row would otherwise auto-chain. These are NOT session boundaries (they don't end the conversation); they BLOCK the next step until a content prerequisite is satisfied. The orchestrator must respect them in the same place it respects session boundaries — between completing one step and starting the next. Currently declared:
+
+- `existing-code` Re-Entry After Completion → **Previous-Cycle Retro Existence Gate** (AZ-900) — blocks the `cycle: state.cycle + 1` increment if no `_docs/06_metrics/retro_*.md` file dated within the closing cycle's range exists. Skipped when `state.cycle == 1`. Presents an A/B/C choice (author now / stub-and-leftover / abort) when triggered. Full spec: `.cursor/skills/autodev/flows/existing-code.md` § "Previous-Cycle Retro Existence Gate".
+
 ### Orchestrator mechanism at a boundary
 
 1. Update the state file: mark the current step `completed`; set the next step with `status: not_started`; reset `sub_step: {phase: 0, name: awaiting-invocation, detail: ""}`; keep `retry_count: 0`.