Add sprint 26-33 roadmap plans and progress update

sprint27_plan.md

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+# Sprint 27 Plan: Constrained Constructive Editing I
+
+## Context
+
+Sprint 27 begins the reliability path for token-efficient, low-hallucination
+execution once taskitems are queued. Markdown-to-taskitem remains a fuzzy
+architect problem; taskitem-to-edit becomes a constrained deterministic problem.
+
+Primary goals:
+1. Define legal operation surface for each taskitem
+2. Restrict symbol/action space to in-scope options
+3. Encode contract checks before and after every edit
+
+---
+
+## Phase 27a: Taskitem Constraint Model (Steps 524-528)
+
+### Step 524: Typed Taskitem Contract Schema (12 tests)
+- Expand taskitem schema with strict fields: allowed targets, allowed ops,
+  allowed symbols, forbidden symbols, expected diagnostics deltas
+- Reject under-specified taskitems for constrained execution path
+
+### Step 525: Legal Operation Graph (12 tests)
+- Build operation graph: insert/update/delete/rename/refactor primitives
+- Bind each primitive to language-specific legal contexts
+- Enforce op availability by AST node kind
+
+### Step 526: Symbol Scope Extractor (12 tests)
+- Build in-scope symbol snapshot per taskitem context
+- Provide explicit candidate set to execution engines
+- Block unresolved symbol references before apply
+
+### Step 527: Constraint Violation Diagnostics (12 tests)
+- New diagnostics for out-of-scope symbol usage and forbidden ops
+- Structured machine-readable error payloads for retry/escalation
+
+### Step 528: Phase 27a Integration (8 tests)
+- Taskitem with complete constraints routes and executes
+- Under-constrained taskitem gets rejected with actionable diagnostics
+
+---
+
+## Phase 27b: Deterministic Apply Guardrails (Steps 529-533)
+
+### Step 529: Pre-Apply Validation Gate (12 tests)
+- Validate candidate edit against legal op graph + symbol snapshot
+- Reject illegal edits before touching source buffer
+
+### Step 530: Post-Apply Structural Gate (12 tests)
+- Re-parse touched region and validate AST integrity
+- Validate no unexpected symbol graph drift
+
+### Step 531: Contract Delta Checker (12 tests)
+- Compare before/after contract set per taskitem expectations
+- Block edits that violate required post-conditions
+
+### Step 532: Retry/Escalation Protocol for Constraint Failures (12 tests)
+- Deterministic retry for correctable failures
+- Escalate to higher-context worker/human only with full failure packet
+
+### Step 533: Sprint 27 Integration + Summary (8 tests)
+- Constrained pipeline prevents out-of-scope edits by construction
+- Hallucinated symbol calls fail fast with explicit diagnostics
+
+---
+
+## Step & Test Summary
+
+| Phase | Steps | Tests | Theme |
+|-------|-------|-------|-------|
+| 27a | 524-528 | 56 | Contract schema, legal ops, scope control |
+| 27b | 529-533 | 56 | Guardrails, structural validation, retry/escalation |
+| **Total** | **524-533** | **~112** | 10 steps |