Incomplete spec ('## Copilot Instructions Block' missing) detected at work phase — pipeline crashes with no recovery path

[shaifulshabuj]

Bug Report

Related to: #2 (gate timeout unrecoverable), #3 (NL misrouting)

Summary

After the plan gate is approved, the worker phase ([2] Implementing...) immediately exits with:

✘ Spec appears incomplete — '## Copilot Instructions Block' section is missing.
✘ Regenerate with: devloop architect "<feature>"
bash-3.2$

The spec file exists and was just reviewed at the plan gate — the user approved a 6963-byte spec — yet the worker validation rejects it. The user is dropped to bare bash with no path forward.

Screenshot

What the screenshot shows:

• Plan gate runs successfully — reads prior task spec (TASK-20260517-010743, 6963 bytes)
• User approves the plan gate: [y]es / [n]o / [e]dit (120s timeout, default = reject) decision> y
• Worker starts: [2] Implementing... Copilot active (next probe for Claude in 6s)
• Immediately fails: Spec appears incomplete — '## Copilot Instructions Block' section is missing.
• Hint: Regenerate with: devloop architect "<feature>" — but no feature name, no TASK-ID, no guidance
• Pipeline stops. User has no way to continue the existing task.

Root Cause

The validation in cmd_work (devloop.sh:5716):

# FIX #7: Validate spec completeness before handing to Copilot
if ! grep -q '^## Copilot Instructions Block' "$spec_file"; then
  error "Spec appears incomplete — '## Copilot Instructions Block' section is missing."
  error "Regenerate with: devloop architect \"<feature>\""
  exit 1
fi

This validation is placed after the plan gate, meaning the user already approved the spec before being told it's invalid. Three compounding problems:

1. Validation happens too late — should be in cmd_architect, immediately after spec is generated
2. Error message is not actionable — says devloop architect "<feature>" without actual feature name or TASK-ID
3. No auto-recovery — when called from cmd_run, the pipeline could automatically re-architect rather than dying

When Does This Happen

• Architect LLM output gets truncated (token limit hit), omitting the ## Copilot Instructions Block section
• Spec was generated by an older DevLoop version that had a different section structure
• Spec was manually edited and the block was accidentally removed
• The resume command loads a spec that pre-dates the ## Copilot Instructions Block format

Expected Behavior

1. Validate spec immediately after cmd_architect generates it:

✘ Spec is incomplete (missing '## Copilot Instructions Block') — retrying architect...
[1] Architecting...  (attempt 2/2)

2. Actionable error message with exact commands:

✘ Spec TASK-20260517-010743 is missing '## Copilot Instructions Block'.
  Hint: devloop architect "add dark mode" --task TASK-20260517-010743
  Hint: devloop work TASK-20260517-010743  (after re-generating)

3. Inside cmd_run, auto-regenerate rather than crash:

⚠ Spec incomplete — re-architecting (attempt 2/2)...
[1] Architecting...

4. Plan gate should not display/approve an incomplete spec — _extract_plan_summary() should warn if ## Copilot Instructions Block is absent.

Suggested Fix Locations

Location	Fix
cmd_architect (line ~5540)	Validate block presence after spec written; retry if missing
cmd_work (line 5716)	Print TASK-ID and feature name in error message
cmd_run work phase	Catch incomplete-spec exit, re-architect inline
approve_plan / plan gate	Warn if spec is missing the Instructions Block before asking for approval

Environment

• DevLoop: v5.1.0
• Spec file size: 6963 bytes (large enough to not be trivially truncated)
• Worker provider: Copilot (with Claude failover)
• Gate: plan gate (approved successfully before worker fails)

[shaifulshabuj]

Screenshot

What this screenshot shows step by step:

1. devloop work TASK-20260517-010743 — user manually triggers the work phase
2. Plan gate runs — reads prior session, finds spec file (6963 bytes), displays file path
3. User approves: [y]es / [n]o / [e]dit (120s timeout) decision> y
4. Worker starts: [2] Implementing... Copilot active (next probe for Claude in 6s)
5. Immediate failure: ✘ Spec appears incomplete — '## Copilot Instructions Block' section is missing.
6. Unhelpful hint: ✘ Regenerate with: devloop architect "<feature>" — no feature name, no TASK-ID
7. bash-3.2$ — dropped to bare prompt, pipeline dead

The spec was already reviewed at the plan gate (6963 bytes, fully visible) yet the worker's second validation fails on the same file — with no way to know what feature string to pass to devloop architect.

---

Fix committed

Commit 10a561a improves the error at cmd_work:

✘ Spec TASK-20260517-010743 is missing '## Copilot Instructions Block' — likely truncated by LLM.
ℹ Regenerate: devloop architect "add dark mode toggle"
ℹ Then retry: devloop work TASK-20260517-010743

The feature name is now extracted from the spec file itself (**Feature**: line), so the user gets an exact, copy-pasteable command.

cmd_architect also now warns immediately after generation if the block header is missing, before the user reaches the work phase.