feat(#79, #80): add task-ID convention, partial delivery, and mode routing

[devallibus]

Summary

Add mode routing to shiplog phases and introduce the task-ID convention for incremental delivery. Analysis phases (brainstorming, discovery classification, PR synthesis, knowledge retrieval, reviews) now recommend plan mode; execution phases recommend agent mode. Claude Code agents can self-switch to plan mode; Codex and Cursor get advisory prompts using the existing routing config.

Also introduces task IDs and partial-delivery PRs from #79 as the mechanism enabling this incremental shipment.

Addresses #79 (completes minimal task-ID convention: T1 task ID format, T2 commit format)
Addresses #80 (completes T1 phase-to-mode mapping, T2 runtime capability model, T3 phase entry check wiring, T5 README update; T4 partial — Claude Code self-switch only)

Completed Tasks

From #79 (task-to-git mapping — minimal subset)

• Task ID format in issue templates (T1, T2, ...)
• Commit message format with task refs (feat(#42/T1): ...)
• Partial-delivery PR template (Addresses #N instead of Closes #N)
• Partial delivery rules in closure-and-review.md
• Retrieval by task ID (git log --grep="#42/T1")

From #80 (mode routing)

• T1: Phase-to-mode mapping table in model-routing.md
• T2: Runtime mode-switching capability model per tool (Claude Code, Codex, Cursor)
• T3: Mode advisories wired into phase entry check in SKILL.md
• T4 (partial): Claude Code self-switch instructions. Codex/Cursor self-switch blocked on upstream.
• T5: README updated with mode routing and task-level delivery sections

Remaining Tasks

#79 (design work deferred)

• Stacked branches per task (threshold rules)
• Checkbox automation from task-level commits
• Envelope task field
• Full task-to-git branching rules

#80

• T4 (remainder): Codex EnterPlanMode/ExitPlanMode self-switch instructions — blocked on upstream

Blocked On

• openai/codex#11180 — EnterPlanMode/ExitPlanMode tools for agent-initiated mode switching in Codex CLI

Journey Timeline

Initial Plan

Mode routing was identified as a gap: shiplog routes by model tier but says nothing about execution mode (plan vs. agent), despite all three target tools supporting the distinction. Issue #80 was created. The partial-delivery pattern from #79 was needed to ship this incrementally since T4 (Codex self-switch) depends on an upstream feature.

What We Discovered

• Claude Code has a hidden exit_plan_mode tool — agents CAN self-switch to plan mode
• Codex has an open feature request (openai/codex#11180) for equivalent capability
• Cursor's Plan-to-Agent auto-switching is a known bug, not a feature
• Shiplog had no mechanism for partial issue delivery — motivating the task-ID convention from feat(#79): define task-to-git mapping — how issue tasks become commits and branches #79

Key Decisions Made

Decision	Choice	Why
Mode routing config	Share confirm/warn/off with tier routing	Avoids config proliferation
Claude Code self-switch	Use capability detection, not hardcoded tool name	exit_plan_mode may be internal/unstable
Task ID scope	Local to issue (T1, not #80-T1)	Simpler, issue number provides namespace
Partial delivery mechanism	Addresses #N instead of Closes #N	GitHub doesn't auto-close; issue stays open naturally

Testing

• Verified all modified files maintain consistent cross-references
• Phase entry check covers both tier and mode transitions
• Partial-delivery template uses status: in-progress envelope (not resolved)

Knowledge for Future Reference

• When Codex ships EnterPlanMode (openai/codex#11180), update references/model-routing.md capability table and add Codex self-switch instructions to SKILL.md.
• The exit_plan_mode tool name comes from community documentation (ClaudeLog), not official Anthropic docs. If the API changes, update the capability table.
• The task-ID convention introduced here is minimal. Issue feat(#79): define task-to-git mapping — how issue tasks become commits and branches #79 tracks the larger design (stacked branches per task, checkbox automation, envelope task field).

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Authored-by: claude/claude-4.6-opus-high-thinking (cursor)
Captain's log — partial delivery by shiplog

[devallibus]

Reviewed-by: openai/gpt-5.4 (codex, effort: high)
Disposition: request-changes
Scope: full diff � README.md, skills/shiplog/SKILL.md, skills/shiplog/references/closure-and-review.md, skills/shiplog/references/model-routing.md, skills/shiplog/references/phase-templates.md

Finding:

• skills/shiplog/references/model-routing.md now says Codex users should switch modes with /plan or Shift+Tab. The cited upstream evidence only establishes that agent-initiated mode switching is missing (openai/codex#11180); it does not establish those user controls, and this Codex harness does not expose them. As written, shiplog would direct Codex users to unsupported controls. Please replace the Codex-specific activation text with a capability-neutral advisory until Codex has a documented mode-switch mechanism.

[devallibus]

[shiplog/amendment] #80: address review finding — Codex mode-switch controls

Finding: PR review flagged that /plan and Shift+Tab were stated as Codex user controls, but openai/codex#11180 only establishes that agent-initiated switching is missing — it does not document those controls.

Fix applied in ff564ad:

• Table row (line 136): replaced "User switches with /plan or Shift+Tab" → "No documented user-initiated mode switch yet."
• Routing prompt (line 154): replaced "Codex: type /plan or press Shift+Tab" → "Codex: switch to plan mode if your tool supports it (no documented mechanism yet)."

Cursor Shift+Tab was left as-is — that is a documented Cursor feature.

Authored-by: claude/opus-4.6 (claude-code)

[devallibus]

Reviewed-by: openai/gpt-5.4 (codex, effort: high)
Disposition: approve
Scope: full diff — README.md, skills/shiplog/SKILL.md, skills/shiplog/references/closure-and-review.md, skills/shiplog/references/model-routing.md, skills/shiplog/references/phase-templates.md

No findings. The task-ID, partial-delivery, and mode-routing changes stay consistent across the skill, reference docs, templates, and README. Local merge simulation against origin/master is clean.