The compile-readiness gate for prompt auto-optimization. Decide whether you have earned the right to run an optimizer (DSPy MIPROv2 / GEPA / BootstrapFewShot) before spending compute. Two preconditions only — a real metric, and enough examples for the optimizer you picked. Garbage metric in, garbage prompt out. Pick the optimizer by data scale; GEPA inverts the scale assumption (~10 examples + textual feedback).
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The compile-readiness gate for prompt auto-optimization. Decide whether you have earned the right to run an optimizer (DSPy MIPROv2 / GEPA / BootstrapFewShot) before spending compute. Two preconditions only — a real metric, and enough examples for the optimizer you picked. Garbage metric in, garbage prompt out. Pick the optimizer by data scale; GEPA inverts the scale assumption (~10 examples + textual feedback).
prompt-compilation — The Compile-Readiness Gate
"It's unproductive to launch optimization runs using a poorly designed program or a bad metric."
— DSPy core team [dspy.ai/learn/optimization/overview/]
"Compile when you can measure. The optimizer maximizes your metric — garbage metric in, garbage prompt out."
— this skill's operating principle (synthesized from the line above + DSPy Case C)
This is an enhancement-overlay decision skill. It answers exactly one question the broad [[dspy]] library
skill buries under API surface: have you earned the right to run an optimizer yet, and which one? It produces a
go / no-go gate plus an optimizer pick. It defers every implementation detail — Signature syntax, module choice,
compile() calls, save/deploy — to [[dspy]] and the full workflow in [[agentsop-dspy]]. It defers metric construction
to [[agentsop-metric-design]]; this skill only checks the metric exists and is validated, then uses it as the gate.
The trap it removes: people reach for MIPROv2(auto="heavy") because the API is right there, before they have a
metric worth maximizing or enough data to avoid memorization. Compilation is a hyperparameter search costing
hundreds-to-thousands of LM calls ($2–$40+, minutes-to-hours) [dspy.ai/faqs/]. Spending that on an un-validated
metric or 8 examples is pure waste.
1. 何时激活 (When to Activate)
Activate when all three of these are plausibly true (the gate then confirms them):
A hand-tuned prompt has plateaued. The team has manually iterated few-shot examples / wording past the point
of obvious returns. Symptom from [[agentsop-dspy]] §1: "the team manually tunes few-shot examples; a metric exists
but isn't being used to drive prompt design."
A metric exists (or can be built). There is a metric(example, pred) -> bool|float — or one can be written
and human-validated. Without this, do not activate; the optimizer has nothing to maximize.
Labeled examples exist. There is a dev set. The count determines which optimizer is even legal (§3, §4.2).
Concrete triggers in intent or codebase:
Trigger
Signal
Spend intent
"auto-tune this prompt", "should I run MIPRO?", "is it worth compiling?", "GEPA vs MIPROv2", "optimize prompts for our metric"
API reach
MIPROv2(, BootstrapFewShot(, dspy.GEPA(, teleprompter, optimizer.compile( about to be called
Symptom
hand-tuned prompt stuck; few-shot examples curated by hand; metric written but only used for reporting, not optimization
Do NOT activate when:
The task is one-shot or the Signature/I-O contract is still churning daily — compile only after it stabilizes
[dspy.ai/learn/optimization/overview/]; otherwise you pay compile cost for prompts you'll throw away.
No metric is possible and none will be built — then this is verbose prompting, not compilation. Route to
[[agentsop-metric-design]] first; if the user refuses any success criterion, the gate stays closed.
You only need parse safety (a typed Signature), not quality optimization — that is [[agentsop-dspy]] Stage 1 and
the signature-design overlay. Promoting prose to a typed Signature and compiling it are two different gates.
2. 核心心智模型 (Core Mental Model)
"Compile when you can measure. The optimizer maximizes your metric — garbage metric in, garbage prompt out."
An optimizer (MIPROv2, GEPA, BootstrapFewShot) is a black-box search over prompt instructions + few-shot demos that
maximizes metric(pred, example). It has no taste. It will faithfully chase whatever the metric rewards, biases
and all. From [[agentsop-dspy]] Case C: "DSPy will optimize toward whatever the metric rewards. A bad metric becomes a
bad program at scale." Two corollaries make this a gate, not a step:
The metric is the precondition, not a tunable. Before any compute is spent, the metric must (a) exist and
(b) agree with human judgment on ≥20 spot-checks. An un-validated metric means the expensive search optimizes
the metric's blind spot. This is non-negotiable [dspy.ai/learn/evaluation/metrics/; Case C]. Construction is
[[agentsop-metric-design]]'s job; this skill only checks the receipt.
Data scale is a hard floor, not a preference. Below the optimizer's example floor you are not training, you
are memorizing. The DSPy 20/80 train/val split exists because "prompt-based optimizers often overfit to small
training sets" [dspy.ai/learn/optimization/overview/]. The floor differs per optimizer (§4.2).
The two-gate picture
┌──────────────────────────────────────────────┐
Gate 1 │ METRIC: exists? AND human-validated ≥20? │ ── No ─► STOP. Build/validate metric ([[agentsop-metric-design]]).
(measure) └──────────────────────────────────────────────┘
│ Yes
▼
┌──────────────────────────────────────────────┐
Gate 2 │ EXAMPLES: ≥ floor for the optimizer I want? │ ── No ─► Pick a lower-floor optimizer, collect data,
(data) └──────────────────────────────────────────────┘ or STOP (use LabeledFewShot as a floor).
│ Yes
▼
COMPILE (cheap probe first: auto="light")
The cost reality (why the gate is worth having)
Compilation runs hundreds-to-thousands of LM calls. Reference run: ~3.2k API calls, $2–$3, 6–20 min for
auto="light"; auto="heavy" on 1000+ examples can hit tens of dollars and hours [dspy.ai/faqs/]. Cost scales with
num_trials × |trainset| × |program LM calls|. The gate's entire job is to stop you spending that on a metric or
dataset that cannot pay it back.
3. SOP (Standard Operating Procedure)
0. Confirm activation (§1): plateaued hand-tuning + metric + examples.
1. GATE 1 — metric exists AND validated ≥20 human spot-checks? [hard]
2. GATE 2 — example count ≥ floor for the chosen optimizer? [hard]
3. PICK — choose optimizer by data scale + feedback signal. (§4.2)
4. BUDGET — estimate cost; cap it; choose a cheap optimizer LM.
5. PROBE — run auto="light" (or smallest config) as a signal.
6. DECIDE — gain ≥ threshold → escalate; else go back, don't escalate.
Gate 1 — Metric (the "can you measure" gate)
Is there a metric(example, pred, trace=None) -> bool|float? If not → STOP, route to [[agentsop-metric-design]].
Has it been validated against a human on ≥20 spot-checks (≥30 if open-ended), with ≥80% agreement? If not →
STOP and validate first. "Never compile against a metric you haven't human-validated on ≥20 spot-checks"
[[[agentsop-dspy]] Case C; dspy.ai/learn/evaluation/metrics/].
Is the metric a single holistic LLM-judge? Then it inherits length / self-preference / position bias and the
optimizer will chase those biases — decompose it ([[agentsop-metric-design]]) before compiling [arxiv.org/pdf/2506.02592].
Exit: a validated metric callable + a calibration receipt. Otherwise the gate is closed; do not proceed.
Gate 2 — Examples (the "enough data" gate)
Count labeled examples. The DSPy-documented thresholds: ≥30 = minimum useful, ~300 = recommended, 200+ required
for MIPROv2 to avoid overfitting [dspy.ai/learn/optimization/overview/]. The floor is per optimizer:
< 10 → only LabeledFewShot(k=8) (no search, weakest) — usually means STOP, collect data.
~10+with textual feedback → GEPA is legal and sample-efficient (this inverts the usual "more data" rule).
Exit: the example count clears the floor of the optimizer you intend to run. If not, either drop to a
lower-floor optimizer or stop.
Step 3 — Pick optimizer by data scale + signal
Use the table in §4.2. The single most important branch: do you have textual error feedback (test diffs, schema
violations, judge rationales like "answer was verbose")? If yes, GEPA needs only ~10 examples and converges faster
because it reflects on the text of the feedback, not just a scalar [dspy.ai/tutorials/gepa_ai_program/;
arxiv.org/abs/2507.19457]. If no, fall back to the data-scale ladder.
Step 4 — Budget
Estimate before launching (§4.4). Cap spend. Use a cheap optimizer LM (e.g. gpt-4o-mini) even when the task LM
is expensive — community-reported parity at a fraction of cost [github.com/stanfordnlp/dspy/issues/1596]. Set
dspy.configure(track_usage=True) to log actual spend.
Step 5 — Probe cheap first
Run auto="light" (MIPROv2) or the smallest config first. Docs: "start with moderate values, observe behavior, and
scale up only if you see clear gains" [github.com/stanfordnlp/dspy/issues/1596]. Never start at auto="heavy".
Step 6 — Decide on the probe result
light gives <2% lift → do not escalate. The bottleneck is the program/metric, not the optimizer. Loop
back to [[agentsop-dspy]] Stage 1 (signature ambiguous? wrong decomposition?) [dspy.ai/learn/optimization/overview/].
light gives 2–10% lift → escalate to medium; go to heavy only if data ≥300 and you have a held-out
test set distinct from val.
Always confirm the final gain on a held-out test set, not the val set used during optimization.
Trigger: Anyone about to call an optimizer's compile().
Action: Run Gate 1 (metric exists + validated ≥20) then Gate 2 (examples ≥ optimizer floor). Any failure → STOP.
Output: Decision token compile-ready | not-ready + the failing gate.
Evidence: [dspy.ai/learn/optimization/overview/]; [[agentsop-dspy]] Case C, §3 three-stage gate.
OP-2 — MetricExistsCheck
Trigger: Gate 1.
Action: Confirm a metric(example, pred, trace=None) -> bool|float exists. If absent → route to [[agentsop-metric-design]], gate stays closed.
Output: Metric callable or a STOP.
Evidence: Anti-pattern "compiling without a metric" [dspy.ai/learn/optimization/overview/].
OP-3 — MetricValidatedCheck
Trigger: Metric exists (OP-2).
Action: Require ≥20 (open-ended ≥30) human spot-checks at ≥80% agreement, plus a calibration receipt. If a single holistic LLM-judge, require decomposition first.
Output: validated flag + receipt reference.
Evidence: [[agentsop-dspy]] Case C step 4; [dspy.ai/learn/evaluation/metrics/]; [arxiv.org/pdf/2506.02592].
OP-4 — ExampleFloorCheck
Trigger: Gate 2.
Action: Count labeled examples; compare to the floor of the intended optimizer (LabeledFewShot any; GEPA ~10+feedback; Bootstrap ~30–50; MIPROv2 200+).
Output: cleared | below-floor + the legal optimizer set.
Evidence: [dspy.ai/learn/optimization/overview/] (30 min / 300 rec / 200+ MIPROv2).
OP-5 — OptimizerByDataScale
Trigger: Both gates passed.
Action: Pick from the §4.2 table by example count and feedback signal. Prefer GEPA when textual feedback exists.
Action: Run auto="light" (or smallest config) first. Never start at heavy.
Output: A cheap lift signal.
Evidence: [github.com/stanfordnlp/dspy/issues/1596]; [[agentsop-dspy]] Case A.
OP-8 — EscalateOrReturn
Trigger: Probe finished.
Action: <2% lift → return to program/metric design (do NOT escalate). 2–10% → medium. heavy only if data ≥300 + held-out test set. Confirm gain on held-out test.
Output: Escalate / iterate-back decision.
Evidence: [[agentsop-dspy]] Case A; [dspy.ai/learn/optimization/overview/].
4.2 — Optimizer-by-data-scale table
Examples
Feedback signal
Optimizer
Why / floor
<10
any
LabeledFewShot(k=8)
No search; weakest. Usually means STOP and collect data. [dspy.ai/cheatsheet/]
Dilemma 1 — Optimizer cost vs gain: is compiling even worth it?
困境: A 3-stage RAG pipeline already hits 72% on dev after manual prompt tuning. MIPROv2(auto="heavy") would
cost ~$40 and 4 hours. Worth it? (Adapted from [[agentsop-dspy]] Case A.)
约束:
250 labeled examples (above the MIPROv2 200-floor) [dspy.ai/learn/optimization/optimizers/].
Pipeline LM = GPT-4o; per-call cost compounds at trial scale.
决策步骤:
Gate 1 first: were the prompts ever scored against the metric, or just eyeballed? If only eyeballed, even
auto="light" (~$2) often yields large lifts over hand-tuned baselines (paper reports 25%/65% over standard
few-shot) [arxiv.org/abs/2310.03714] — the metric was never actually driving design.
Probe light (~$2), never heavy (OP-7). It is a cheap signal for whether more compute helps.
<2% lift → do NOT escalate to heavy. Return to program/metric: signature ambiguous? is 3-stage the right
decomposition? (OP-8) [github.com/stanfordnlp/dspy/issues/1596].
2–10% lift → medium; heavy only if data ≥300 + a held-out test set distinct from val.
Use gpt-4o-mini as the optimizer LM even though the task LM is gpt-4o (OP-6) — community parity.
结果: The $40 heavy run is almost never the right first move. The $2 probe tells you whether to spend more or
to go fix the program. Often the answer is "fix the program/metric first."
可提取的操作: OP-1, OP-6 CostBudgetGuard, OP-7 CheapProbeFirst, OP-8 EscalateOrReturn. Lesson: never
open at heavy. Probe light with a cheap optimizer LM, and treat <2% as a signal to fix the program, not to add
compute.
Dilemma 2 — Only 12 examples: GEPA inverts the data-scale assumption
困境: A code-fix agent has just 12 labeled examples, but each failing run produces rich textual feedback:
the failing test diff, a schema-violation message, a linter error. The data-scale ladder says 12 < 30 → "STOP,
collect data, you can't optimize." Is that right?
约束:
12 examples is below the BootstrapFewShot (~30) and MIPROv2 (200) floors.
Collecting 200+ labeled examples is weeks of effort.
But the failures emit machine-readable text feedback, not just a pass/fail scalar.
决策步骤:
Gate 1: a metric exists — pass/fail on the test plus a textual feedback string. Validate it (the test is
ground truth; spot-check the feedback strings are accurate). Pass.
Gate 2 — do NOT apply the scalar-data ladder. The presence of textual feedback changes which optimizer is
legal. GEPA needs only ~10 examples because it reflects on the content of the feedback, not a scalar gradient
[dspy.ai/tutorials/gepa_ai_program/; arxiv.org/abs/2507.19457]. 12 ≥ ~10 → GEPA is legal.
Pick GEPA (OP-5): return dspy.Prediction(score=..., feedback="failing assert: expected X got Y") from the
metric; this is GEPA's superpower [dspy.ai/api/optimizers/GEPA/overview/].
Probe cheap (OP-7), confirm lift on the held-out examples (OP-8).
结果: A dataset that is far too small for MIPROv2/Bootstrap is sufficient for GEPA. The "you need 200 examples"
intuition is specific to scalar-feedback optimizers; textual feedback buys an order-of-magnitude in sample
efficiency. GEPA reported beating MIPROv2 by 10–13% on benchmarks while being more sample-efficient
[arxiv.org/abs/2507.19457].
可提取的操作: OP-4 ExampleFloorCheck, OP-5 OptimizerByDataScale. Lesson: the example floor is per-optimizer.
If you can express why an output failed as text, GEPA inverts the data-scale assumption — ~10 examples suffice.
Do not reflexively gate out small datasets that carry rich feedback.
6. 反模式与边界 (Anti-Patterns & Boundaries)
Anti-patterns
#
Anti-pattern
Why it's wrong
Fix
AP-1
Compiling without a metric
The optimizer has nothing to maximize; DSPy degenerates to verbose prompting
Refuse the compile; build a metric (OP-2, [[agentsop-metric-design]])
AP-2
Compiling against an un-validated single LLM-judge
The search faithfully chases the judge's length / self-preference / position bias [arxiv.org/pdf/2506.02592]
Validate ≥20 spot-checks; decompose the judge (OP-3)
AP-3
Compiling on <10 examples (scalar feedback)
Below the floor you memorize, not train; "prompt-based optimizers overfit small sets" [dspy.ai/learn/optimization/overview/]
Collect data, or use LabeledFewShot as a floor — or GEPA if textual feedback (OP-4)
AP-4
Starting at auto="heavy"
Tens of $ / hours before you know if compute even helps
Probe auto="light" first (OP-7)
AP-5
Escalating after a <2% probe lift
The bottleneck is the program/metric; more compute won't fix it
Return to [[agentsop-dspy]] Stage 1 (OP-8)
AP-6
Using the expensive task LM as the optimizer LM
Multiplies trial-scale cost for no documented gain
Cheap optimizer LM (gpt-4o-mini) (OP-6)
AP-7
Applying the scalar data-floor to a feedback-rich task
Wrongly gates out GEPA-legal small datasets
Check for textual feedback before counting examples (OP-5)
AP-8
Reporting the gain on the val set used in optimization
Overfit signal; not a real held-out improvement
Confirm on a held-out test set distinct from val (OP-8)
AP-9
Compiling while the Signature/I-O contract is still churning
You pay compile cost for prompts you'll throw away
Stabilize the contract first (signature-design / [[agentsop-dspy]] §1)
Boundaries (when this skill cannot help)
No willingness to define any success criterion — no metric can exist; the gate stays closed. Problem
definition first ([[agentsop-metric-design]], then scientific-critical-thinking).
Parse-safety, not quality — if you only need a typed Signature so code can consume the output, that is the
promote gate (signature-design / [[agentsop-dspy]] Stage 1), a different decision from compile.
HOW to write/run the optimizer — class syntax, compile() args, save/deploy: that is [[dspy]] and
[[agentsop-dspy]], not this overlay.
Constructing the metric — decomposition, bias probes, calibration receipts: that is [[agentsop-metric-design]].
This skill only checks the receipt exists.
Non-DSPy auto-optimization — e.g. OpenAI fine-tuning is a weights path, not prompt compilation; the
readiness logic (metric + data floor) still applies but the operators differ (§7).
7. 跨框架对照 (Cross-Framework Mapping)
The readiness gate (metric + data floor) is framework-agnostic; the operators differ.
Concept
DSPy optimizers
Manual few-shot tuning
OpenAI fine-tuning
What is optimized
prompt instructions + demos (and optionally weights via BootstrapFinetune)
the prompt string, by hand
model weights
Metric required?
Yes — metric(ex, pred) -> bool|float drives the search
implicit / eyeballed (the failure mode)
a held-out eval set + loss; eval suite recommended
OpenAI guidance: ~50–100+ examples minimum, more is better
Cost shape
`num_trials ×
trainset
× calls` ($2–$40+) [dspy.ai/faqs/]
Readiness gate (this skill)
both gates apply directly
Gate 1 is exactly what's missing — you're "tuning" with no validated metric
both gates apply; "metric validated" = your eval set is trustworthy
When to prefer
metric + ≥10 examples + want a portable, recompilable artifact
one-shot, unstable contract, or audit-mandated verbatim prompts
task is stable, latency/cost matters at high volume, prompt optimization plateaued
Decision summary: If you have a validated metric and examples clearing a floor, compile (DSPy). If you
have a metric but it's never been validated, you are doing manual tuning dressed up — close Gate 1 first. If
prompt optimization has plateaued and you have hundreds of stable examples and volume justifies it, consider
fine-tuning (or BootstrapFinetune to distill an already-compiled program into a smaller model).
Combination patterns:
prompt-compilation + [[agentsop-metric-design]]: this skill's Gate 1 is satisfied by a [[agentsop-metric-design]]
calibration receipt. No receipt → gate closed.
prompt-compilation + [[agentsop-dspy]]: this overlay is the sharpened version of [[agentsop-dspy]] §3 Stage 2→3
transition (the "are you allowed to compile yet?" boundary). After the gate opens, hand off to [[agentsop-dspy]] for
the full compile/save/deploy workflow.
prompt-compilation + [[dspy]]: [[dspy]] provides the optimizer APIs; this skill decides whether and
which.
References
references/R1-source-evidence.md — every claim traced to the local dspy-sop skill and the upstream DSPy docs it cites; overlap check vs [[dspy]] and [[agentsop-metric-design]].
intermediate/operation_candidates.json — the 8 operations + tables in machine-readable form.
