Analog Evolve

analog-evolve

Self-evolution engine. Reviews completed design sessions and improves analog-agents' knowledge base, checklists, and prompts.

Inspired by the principle: every design session should make the next one smarter.

When to Use

• After a sub-block converges (auto-suggested by analog-pipeline)
• After a project completes
• After a design fails and is abandoned (failure teaches more than success)
• Manually: /analog-evolve review to review the current session

Evolution Dimensions

1. Wiki Enrichment — "What did we learn?"

Review iteration-log.yml and the design trajectory. For each sub-block:

Extract lessons automatically:

• Parameter changes that fixed a failing spec → candidate strategy entry

  • "Increasing L from 60n to 120n on mirror M3/M4 fixed the 15% current mismatch"
  • → wiki/strategies/longer-l-for-mirror-matching.yml

• Corner surprises (spec passed at TT, failed at SS/FF) → candidate corner-lesson

  • "Comparator offset 3x worse at SS/125C vs TT/27C"
  • → wiki/corner-lessons/ss-corner-offset-blowup.yml

• Design traps encountered during iteration → candidate anti-pattern

  • "CMFB on lower cascode device gave weak CM loop gain"
  • → wiki/anti-patterns/cmfb-on-lower-cascode.yml

• Successful topology + sizing for a block type → candidate block-case

  • Archive the converged design as a reference case

Confidence escalation:

• New entries start as confidence: unverified
• If a similar lesson is discovered in a second project, escalate to verified
• If a lesson contradicts a later finding, add contradicts edge

Process:

1. Read iteration-log.yml (full trajectory)
2. Read all verifier-reports/ (what failed, what passed, what was marginal)
3. Read circuit/rationale.md (designer's reasoning)
4. Read cross-model review reports (if any)
5. For each potential entry: a. Check if a similar entry already exists in wiki (search by tags) b. If exists: update with new evidence, escalate confidence, add validated edge c. If new: create entry with confidence: unverified, add derived_from edge to project
6. Present proposed entries to user for approval before writing

2. Checklist Evolution — "What should we check next time?"

Analyze the design session for issues that SHOULD have been caught by a checklist but weren't:

Detection patterns:

• Verifier pre-sim rejection that doesn't match any existing checklist item → propose new checklist entry
• Issue discovered only after 2+ iterations that could have been caught structurally → propose new checklist entry with effort: lite
• Cross-model reviewer flagged a risk not in any checklist → propose new checklist entry

Process:

1. Read all verifier rejection reports
2. For each rejection, check if it matches an existing checklist entry
3. Unmatched rejections → draft new checklist entries with full 7-field schema
4. Read cross-model review reports for topology risks flagged
5. Cross-check against checklists/*.yml
6. Present proposed entries to user, specify which checklist file they belong in

Example output:

## Proposed Checklist Addition

**File:** checklists/folded-cascode.yml

```yaml
cmfb_control_device_sizing:
  description: "CMFB-controlled device must be wide enough for regulation authority"
  method: semantic
  severity: warn
  effort: standard
  auto_checkable: false
  references: [anti-003]
  how: >
    The CMFB-controlled device (usually upper PMOS in cascode load) acts as
    a variable current source. Its gate is set by the CMFB loop, not by fixed
    bias. Size it wide enough that CMFB can regulate across the full output CM
    range. Applying a fixed gm/Id target (e.g., gm/Id=10) can make it too
    narrow, starving load current and collapsing output CM.

Reason: This issue caused 2 extra iterations on the OTA sub-block. The verifier rejected the netlist twice for output CM stuck at rail, which was traced to undersized M7 (CMFB-controlled PMOS).

### 3. Prompt Refinement — "How should we instruct better?"

Analyze failure patterns across sessions to identify where agent prompts
could be improved:

**Detection patterns:**
- Designer repeatedly makes the same sizing mistake across projects
  → add a warning to `prompts/designer-prompt.md`
- Architect consistently underestimates noise budget
  → add a calibration note to `prompts/architect-prompt.md`
- Verifier misses a class of testbench errors
  → add to verifier's pre-sim review checklist in `prompts/verifier-prompt.md`

**Process:**
1. Review the session's failure trajectory
2. Identify root causes: was it a sizing error? testbench error? architecture error?
3. For each root cause, check if the relevant prompt already warns about it
4. If not: draft a specific addition to the prompt (exact text, exact location)
5. Present proposed prompt changes to user for approval

**Important:** prompt changes are PROPOSED, never auto-applied. The user
reviews and merges. This prevents prompt drift from accumulating noise.

### 4. Design Memory — "Remember this user's preferences"

Track user-specific design preferences that should persist across sessions:

- Preferred topologies ("always try folded cascode first for OTAs")
- Process-specific tricks ("in 28nm, use ulvt for input pair, lvt for everything else")
- Naming conventions ("use net_vbp for PMOS bias, net_vbn for NMOS bias")
- Effort preferences ("always use intensive for comparators")
- Review preferences ("skip qwen, it gives too many false positives on this process")

Storage: `wiki/user-preferences.yml` (gitignored with projects/)

```yaml
# user-preferences.yml — auto-discovered, user-confirmed
preferences:
  - category: topology
    rule: "Prefer folded cascode for single-stage OTA"
    discovered: 2026-04-16
    confirmed: true

  - category: process
    rule: "28nm: ulvt for input pair, lvt for mirrors and cascodes"
    discovered: 2026-04-16
    confirmed: true

  - category: effort
    rule: "Always use intensive effort for comparator blocks"
    discovered: 2026-04-16
    confirmed: false  # proposed, not yet confirmed

Subcommands

Integration with Pipeline

analog-pipeline auto-triggers /analog-evolve review at two points:

1. After each sub-block converges (lightweight: wiki + checklist only)
2. After project completion (full: all 4 dimensions)

Effort interaction:

Tool Backend

All evolution analysis is powered by tools/evolve_engine.py:

The tool reads design artifacts (iteration-log.yml, verifier-reports/, rationale.md), analyzes patterns, and outputs proposals in markdown. The skill (this SKILL.md) provides the context and judgment for interpreting proposals and deciding what to accept.

Principles

1. Propose, never auto-apply. All changes are presented to the user first. The only exception is confidence escalation on existing wiki entries (low-risk, evidence-based).

2. Evidence-based. Every proposal includes the specific design event that triggered it (iteration number, failing spec, measured value).

3. Convergent, not divergent. Evolution should make the system more precise, not more verbose. If a checklist already has 20 items for a topology, think twice before adding a 21st. Merge or refine existing items instead.

4. Failure teaches more than success. Pay more attention to failed iterations, abandoned designs, and escalation events than to smooth convergence.

5. Cross-session learning. When /analog-wiki consult returns entries with confidence: unverified, the current session's results can validate or invalidate them. This is how single-project observations become verified knowledge.