xoai/session-bridge

<!-- sage-metadata cost-tier: haiku activation: auto tags: [context, persistence, session, continuity] inputs: [codebase] outputs: [session-state] -->

Session Bridge

Maintain continuity across sessions using the plan file as the source of truth.

Core Principle: The file system is the source of truth. What artifacts exist in .sage/work/ and their frontmatter status tells you where things stand. decisions.md provides reasoning context that helps find the active work quickly. State updates happen at checkpoints (Rule 7), not per-task.

State Architecture

Two levels of state, each with a different purpose:

Ground Truth: Artifacts in .sage/work/

.sage/work/<feature>/ contains artifacts with YAML frontmatter:

• brief.md, spec.md, plan.md — each with status and phase
• Status field: pending, in-progress, completed, blocked
• The EXISTENCE of artifacts and their frontmatter status IS the state

This is always accurate because artifacts are created and updated as part of the workflow. No separate "save" action needed.

Context: decision logs

Each initiative's .sage/work/[initiative]/decisions.md is the per-cycle log; the global .sage/decisions.md is a shared cross-initiative log. Both are places where the agent and human write significant decisions and context. It provides reasoning that artifact frontmatter doesn't capture — WHY decisions were made, what alternatives were considered, and what the human's priorities are.

Loading (Start of Session)

When resuming work, follow this priority order:

Step 1: Scan artifacts for state

Scan .sage/work/ for active initiatives. Read frontmatter from manifest.md, brief.md, spec.md, or plan.md (whichever exists). Note title, status, phase. If a plan exists, scan the task checkboxes to understand how far implementation progressed.

This is the source of truth — what artifacts exist tells you where the project stands.

Branch matching (git projects): read the current branch and match it against the recorded branch: field in each initiative's manifest frontmatter (git-discipline records it at branch creation — match on the recorded field, never re-derive from branch or directory names). Prefer the initiative whose recorded branch matches HEAD in the resume menu; if HEAD is on the default branch while initiative branches exist, list them.

Owner exclusion (parallel worktrees): exclude initiatives whose manifest carries an owner: pointing at a different checkout — compare git rev-parse --show-toplevel against the recorded owner: after path normalization (trailing slashes, symlinks). They belong to another worktree's session. A session opened inside a worktree auto-resumes that worktree's checked-out initiative by the same branch-matching rule.

Step 2: Read decisions for context

Read the matched initiative's own decision log first — .sage/work/[initiative]/decisions.md — then the global .sage/decisions.md (cross-initiative decisions; older projects may have only the global file). Read the last 3-5 entries of each. These capture recent decisions and direction changes — WHY the project is in its current state, not just WHAT state it's in.

Step 3: Verify against the codebase

If artifacts and the codebase disagree (e.g., plan says "spec phase" but implementation files exist), trust the codebase. The file system is the ultimate source of truth. Update artifacts to match reality.

Step 4: Report to human

Sage: Resuming [feature name]. [Phase] phase. [Summary of what exists and what's next.]

Saving (At Checkpoints)

State updates happen ONLY at checkpoints (Rule 7), not per-task:

At each checkpoint:

Prepend significant decisions to the initiative's decision log (.sage/work/[initiative]/decisions.md; cross-initiative decisions go to the global .sage/decisions.md):

### 2025-03-13 — Token storage decision
Chose httpOnly cookies over localStorage for JWT storage.
XSS protection outweighs CSRF handling cost.
spec.md updated with cookie-based auth approach.

Update artifact frontmatter if status changed.

After discovering conventions:

Append to .sage/conventions.md:

### Error handling
Project uses a centralized error handler in src/middleware/error-handler.ts.
All route handlers throw typed errors; the middleware formats the response.

Saving (End of Session)

If the session is ending gracefully (human says "stop", "done for now"):

1. Update artifact frontmatter to reflect current phase
2. Prepend session summary to the initiative's decisions.md if significant work was done
3. Report: "Sage: Session saved. Type /build to resume next time."

If the session ends abruptly: the artifacts in .sage/work/ and their frontmatter reflect the real state. The next session's slash command auto-pickup reads them to orient.

FIX Mode State

FIX mode typically doesn't have plan artifacts. For FIX mode:

• Root cause and fix are recorded in decisions.md at the close checkpoint
• State is simpler because fixes usually complete in one session
• If interrupted, the next /fix command scans for in-progress fix work

Recovery

No artifacts found: "Sage: Fresh project, no work in progress."

All artifacts completed: "Previous initiative [name] is complete. Ready for a new task."

Artifacts and codebase disagree: Always trust the codebase (git log, file existence) over artifacts. Update artifact frontmatter to match.

Rules

• Artifacts in .sage/work/ are the ground truth for state.
• decisions.md is the ground truth for reasoning and context.
• Update state at checkpoints only (Rule 7), not per-task.
• Prepend to decisions.md — never overwrite. Append to conventions.md.
• If state is ambiguous, verify against the codebase.

Failure Modes

• No artifacts found: Fresh project. Report and ask what to build.
• Multiple in-progress initiatives: Ask the human which to resume. Don't guess — the wrong choice wastes a session.
• Artifacts and codebase disagree: Trust the codebase. Update artifacts to match reality. update the spec status.
• Multiple initiatives have in-progress artifacts: Ask the human which to resume. Don't guess — the wrong choice wastes a session.